[top]
000
FXUS66 KOTX 230013
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
253 PM PST SUN NOV 22 2009
.SYNOPSIS...
THE STRONG LOW PRESSURE SYSTEM BRINGING WIDESPREAD SNOW AND RAIN
TO THE INLAND NORTHWEST WILL TRACK OUT OF THE REGION
OVERNIGHT...BRINGING IMPROVING CONDITIONS TO ALL LOCATIONS. A
RIDGE WILL THEN BEGIN TO BUILD OVER THE PACIFIC NORTHWEST AND
PERSIST THROUGH THANKSGIVING. DESPITE THE PRESENCE OF THE
RIDGE...A WEAK WARM FRONT WILL BRING A CHANCE OF LIGHT RAIN AND
SNOW MAINLY TO LOCATIONS NORTH OF I90. AFTER THANKSGIVING...THE
RIDGE WILL BREAK DOWN ALLOWING A STRONG COLD FRONT TO CROSS THE
AREA POSSIBLY BRINGING A RETURN TO WINTRY WEATHER.
&&
.DISCUSSION...
TONIGHT...WINTER HIGHLIGHTS WILL REMAIN IN EFFECT ACROSS THE
CENTRAL PANHANDLE MTNS AS WELL AS THE IDAHO PALOUSE AND NORTHERN
BLUE MTNS AS SATELLITE AND RADAR IMAGERY CONTINUE TO ILLUSTRATE A
TIGHT CIRCULATION AND MODERATE TO LOCALLY HEAVY PRECIPITATION
BANDS MOVING THROUGH. SNOW ACCUMULATIONS AS OF 2PM PST LOOK TO BE
AT AND ABOVE MAINLY 2500 BUT ANTICIPATE THIS TO LOWER SLIGHTLY
WITH SUNSET AND LOSS OF DAYTIME HEATING. ALTHOUGH SNOW IS FALLING
IN THE WASHINGTON PALOUSE...NO WINTER HIGHLIGHTS ARE EXPECTED AT
THIS TIME. THIS INCLUDES THE PULLMAN AREA WHICH HAS BEEN REPORTING
MOD-HVY SNOW THE LAST FEW HOURS...HOWEVER ASOS AMONGST SPOTTERS IN
THE AREA ARE REPORTING WELL ABOVE FREEZING TEMPERATURES AND CAMS
ONLY SUGGESTING SMALL ACCUMULATIONS OF SLUSH UNDER THE HEAVIEST
BANDS. THEREFORE...THE AREA OF FOCUS FOR THE NEXT 6 HOURS WILL BE
IN THE IDAHO PALOUSE AND SOUTHERN PANHANDLE MTNS WHERE STRONG
SOUTHWEST UPSLOPE FLOW WILL PERSIST THROUGH 06Z BEFORE TAPERING
OFF TO ISOLATED LIGHT SHWRS AS THE MIDLEVEL CIRCULATION JUMPS INTO
WESTERN MT AND UPPER-LEVELS BEGIN TO DRY AND QUICKLY STABILIZE.
FURTHER SOUTH AND WEST...FLOW IN THE MID LEVELS CONTINUES TO SHOW
MORE OF A WESTERLY COMPONENT AND THIS IS SUPPORTING STRONG UPSLOPE
INTO THE NORTHERN BLUE MTNS. A SPOTTER IN THE ANATONE
AREA...NEARLY 3800` HAS REPORTED AS MUCH AS 7 INCHES SINCE 9PM
LAST NIGHT.
AS TEMPERATURES COOL WITH SUNSET...THERE IS SOME CONCERN THAT
THIS AFTERNOON`S PRECIPITATION WHICH APPEARED TO MELT ON ROADWAYS
ACROSS ALL LOCATIONS BELOW 2000` TO REFREEZE WITH AREAS OF BLACK
ICE FORMING...SO EVEN WITHOUT WINTER HIGHLIGHTS IN
EFFECT...RESIDENTS SHOULD PLAN FOR ICY CONDITIONS...ESPECIALLY IN
THE EARLY MORNING HOURS JUST PRIOR TO SUNRISE.
WITH A SLIGHTLY MORE SOUTHERN STORM TRACK...WE DO NOT EXPECT
HE HIGH WINDS ACROSS OUR LOWER BASIN AND PALOUSE BUT STILL IN
THE BREEZY CATEGORY THROUGH THE NIGHT. THIS SHOULD PREVENT ANY FOG
FROM FORMING OUTSIDE THE PROTECTED VALLEYS BUT WILL LIKELY PROMOTE
LOW STRATUS AND DRIZZLE ACROSS AREAS OF SPOKANE AND PULLMAN
THROUGH THE NT. FURTHER NORTH...INCLUDING COLVILLE...DEER
PARK...AND SANDPOINT...HAVE LEFT PATCHY FOG IN THE FORECAST WITH
LIGHT WINDS AND EARLY MORNING CLEARING ANTICIPATED./SB
MONDAY THROUGH WEDNESDAY...LOOKS LIKE THE WEATHER WILL FINALLY TURN A BIT
MORE TRANQUIL DURING THIS PERIOD. A LOOK AT THE UPPER LEVEL
5-WAVE CHARTS REVEALS THE FORMATION OF A LONGWAVE RIDGE OVER THE
PACNW. WHILE LONGWAVE RIDGES TYPICALLY BRING DRY WEATHER...THIS
RIDGE WILL BE A LITTLE DIRTY WHICH SUBSEQUENTLY ALLOWS A COUPLE
WEAK FRONTS TO NEAR THE REGION. JUST HOW STRONG THESE FRONTS WILL
BE AND HOW MUCH MOISTURE THEY WILL CARRY WILL BE THE BIG QUESTION.
BEFORE THE FIRST FRONT ENTERS THE PICTURE HOWEVER WE WILL STILL DEAL WITH
RESIDUAL MOISTURE FROM TODAYS TROF. BY MIDDAY ALL SHORT RANGE
MODELS TAKE THE TROF INTO CENTRAL MONTANA. WEAK UPSLOPE SW FLOW
COULD PRODUCE A FEW SHOWERS OVER THE IDAHO PANHANDLE...HOWEVER
THROUGH THE DAY...THE POTENTIAL INSTABILITY BECOMES QUITE SHALLOW
AND BY AFTERNOON IS LIKELY TOO SHALLOW TO SUPPORT SHOWERS.
MEANWHILE THE AFOREMENTIONED FRONT BEGINS TO PUSH ONTO THE COAST
BY AFTERNOON. THE CURRENT POSITION OF THE WARM FRONT IS JUST WEST
OF 130W AND WAS HANDLED WELL BY ALL MODELS AS OF 18Z.
WHAT HAPPENS AFTER THE FRONT PUSHES ONTO THE COAST AGAIN WILL BE THE
BIG QUESTION. ALL THE MODELS TAKE TO FRONT AND BEGIN TO NUDGE IT
THROUGH THE MEAN UPPER LEVEL RIDGE POSITION...ALL THE WHILE
TRANSITIONING FROM ITS CURRENT N-S ORIENTATION TOWARD MORE OF A
ZONAL E-W ORIENTATION. THIS MAKES SENSE GIVEN THE MEAN RIDGE
POSITION...BUT HOW FAR SOUTH WILL THE FRONT SURGE AND HOW LONG
WILL IT HOLD TOGETHER. THE ECMWF AND GFS SOLUTIONS ARE THE WEAKEST
AND DRIEST SOLUTIONS AND KEEP MOST IF NOT ALL PRECIPITATION OVER
THE FAR NORTHERN ZONES THROUGH EARLY TUESDAY MORNING. QPF AMOUNTS
ARE FAIRLY LIGHT. MEANWHILE THE NAM SOLUTION IS DECIDEDLY WETTER
AND MORE AGGRESSIVE IN PUSHING THE FRONT SOUTH ON TUESDAY. NOT
SURPRISINGLY THE NAM HAS THE SUPPORT OF THE SREF
SOLUTIONS...HOWEVER ITS HARD TO ARGUE WITH THE GFS AND
ECMWF...ESPECIALLY SINCE THEY AGREE SO WELL WITH ONE ANOTHER. THE
CANADIAN MODEL IS A LITTLE WETTER...BUT IT TOO KEEPS MOST OF THE
PRECIPITATION OVER THE FAR NORTHERN ZONES. WE WILL STICK WITH THE
ECMWF/GFS BLEND AND KEEP LIGHT QPF AMOUNTS FIXED OVER THE FAR
NORTHERN ZONES. GIVEN THE PERSISTENT WESTERLY FLOW IN THE 850-700
MB LAYER...WE WILL PUT DRIER RAIN SHADOW AFFECTS IN THE LEE OF THE
CASCADES. EVEN THE WETTEST QPF AMOUNTS FROM THE GFS AND ECMWF
SUGGEST SNOW AMOUNTS OVER ALL LOCATIONS WOULD BE AN INCH OR LESS.
THROUGH TUESDAY NIGHT AND WEDNESDAY...THE UPPER LEVEL RIDGE AMPLIFIES
EVEN FURTHER...PUSHING THE WARM FRONT NORTH OF THE CANADIAN
BORDER AND WARMING UP MOST LOCATIONS. SNOW LEVELS BY WEDNESDAY
WILL SURGE ABOVE 5000 FEET OVER THE SOUTHERN 2/3RDS OF THE
CWA...WITH LEVELS BETWEEN 2000-3000 FT ACROSS THE FAR NORTH. BY
LATE WEDNESDAY...THE RIDGE AXIS BEGINS TO SHIFT A LITTLE
EAST...ALLOWING THE TRAILING COLD FRONT TO NEAR THE CASCADES. THE
GFS AND ECMWF SOLUTIONS BRING SOME PRECIPITATION TO THE NORTH
CASCADE CREST LATE IN THE DAY...BUT THE FOCUS FOR PRECIPITATION
WILL LIKELY STILL LIE WEST OF THE CREST. MEANWHILE THE NAM AND
SREF SOLUTIONS CONTINUE THEIR WET TRENDS AND SPILL LIGHT TO
MODERATE PRECIPITATION OVER THE NORTHERN TIER OF ZONES. A DPROG/DT
FROM BOTH THE GFS AND ECMWF SUGGESTS THE TIMING MAY BE SPEEDING UP
JUST A TAD...BUT STILL NOTHING AS FAST OR AS WET AS THE NAM.
GIVEN THE INCREASING STABILIZATION OVER THE INLAND NW...WE SUSPECT
FOG AND STRATUS WILL BECOME MORE EXPANSIVE WITH TIME...HOWEVER IF
THE FRONT IS TRULY AS WET AND AS PROGRESSIVE AS THE NAM
SUGGESTS...THE COVERAGE WILL BE MINIMAL. FX
WEDNESDAY NIGHT THROUGH SUNDAY...AMPLIFIED RIDGING AHEAD OF AN
INCOMING SLOW MOVING/STALLED FRONTAL ZONE DRAPED ALONG THE WEST
SIDE AND APEX OF THE RIDGE REMAINS IN THE VICINITY WEDNESDAY NIGHT
INTO THURSDAY. AS THE FRONT APPROACHES FROM THE WEST THE PART
DRAPED ALONG THE APEX PIVOTS TO THE NORTH AND INTO SOUTHERN
BRITISH COLUMBIA WITH TIME ALLOWING FOR MINOR POPS FOR ANY
RAIN/SNOWFALL ASSOCIATED WITH IT ALONG THE BRITISH COLUMBIA BORDER
AND NEAR THE CASCADE CREST. THE FRONT SWEEPS THROUGH IN A
NEGATIVELY TILTED FASHION THURSDAY NIGHT ALLOWING THE HIGH POPS
FOR RAIN/SNOW ASSOCIATED WITH IT TO SPREAD FROM WEST TO EAST
ACROSS THE FORECAST AREA INTO FRIDAY. WEAK SHORTWAVE RIDGING IN
THE WAKE ALLOWS FOR DECREASING POPS FOR THE WEEKEND...HOWEVER THE
RIDGE ALOFT IS EXTREMELY WEAK...ALMOST FLAT...AND AS SUCH IS MUCH
MORE SUSCEPTIBLE TO NUISANCE SHORTWAVE MIGRATION...THUS POPS ARE
NOT ZEROED OUT BUT ARE SUBSTANTIALLY LOWER IN COMPARISON TO THE
WORKWEEK. /PELATTI
&&
.AVIATION...
SFC LOW CONTINUES TO TRACK EAST THROUGH AREAS OF SE WA
INTO CENTRAL IDAHO THIS EVENING WITH CONTINUED -SN/SN ACROSS
THE PALOUSE AND CENTRAL PANHANDLE MTNS OF IDAHO. EXPECT LOCAL
IFR/LIFR CONDITIONS UNDER THE HEAVIER SHWRS WITH WIDESPREAD MTN
OBSCRNS. SHOWERS WILL CONTINUE TO GRADUALLY TAPER OFF NORTH
ALONG THE KGEG-KCOE CORRIDOR BUT INCR SW FLOW WILL LEAD TO
INCR STRATUS OVERNIGHT LOWERING CIGS AND VIS INTO IFR CONDITIONS
WHICH IS EXPECTED TO LINGER THROUGH 19Z MONDAY. FURTHER WEST...
DRIER AIR WILL CONTINUE TO BRING VFR CONDITIONS UNDER
LIGHT WINDS.
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 28 37 31 39 29 41 / 30 10 50 10 0 0
COEUR D`ALENE 30 37 31 40 29 41 / 60 10 60 20 10 10
PULLMAN 29 40 31 42 32 43 / 80 10 30 30 0 0
LEWISTON 33 45 33 48 32 45 / 50 0 10 20 0 0
COLVILLE 30 38 31 38 32 41 / 10 30 70 20 30 10
SANDPOINT 30 36 29 36 29 35 / 30 30 70 30 30 10
KELLOGG 30 33 29 37 32 38 / 90 30 50 30 10 10
MOSES LAKE 25 43 30 44 30 45 / 0 10 20 10 0 0
WENATCHEE 31 42 34 45 33 44 / 10 10 10 10 10 10
OMAK 24 40 31 44 29 44 / 0 50 60 10 30 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR IDAHO
PALOUSE.
WINTER STORM WARNING UNTIL 1 AM PST MONDAY FOR CENTRAL PANHANDLE
MOUNTAINS.
WA...WINTER WEATHER ADVISORY UNTIL 10 PM PST THIS EVENING FOR
NORTHEAST BLUE MOUNTAINS.
&&
$$
[top]
000
FXUS66 KSEW 222325
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
325 PM PST SUN NOV 22 2009
.SYNOPSIS...A LOW PRESSURE SYSTEM WILL CONTINUE TO MOVE INLAND
OVERNIGHT. WESTERLY GALES OVER THE COASTAL WATERS AND IN THE STRAIT
OF JUAN DE FUCA WILL DECREASE BY MIDNIGHT. SNOW SHOWERS WILL BE
HEAVY AT TIMES THROUGH THE EVENING IN THE MOUNTAINS. A WARM FRONT
WILL MOVE THROUGH THE AREA MONDAY EVENING...FOLLOWED BY ANOTHER WARM
FRONTAL SYSTEM AROUND WEDNESDAY NIGHT. A COLD FRONT IS POSSIBLE BY
FRIDAY.
&&
.SHORT TERM...SEA TAC AND TACOMA NARROWS AND HOQUIAM GUSTING TO ARND
30 MPH AT 3PM BUT I HAVE LET THE WIND ADVISORY EXPIRE NOW AS WE WONT
LIKELY MUCH MORE THAN THAT INTO THE EVENING AS GRADIENTS COME DOWN.
FINALLY BREEZY HERE AT THE OFFICE ON LAKE WASHINGTON...OLM-BLI
GRADIENT PEAKED AT +4.5MB EARLY IN THE AFTERNOON BUT THE WINDS IN
THE SOUTH SOUND JUST WOULD NOT SHIFT INTO NORTH SEATTLE AND
EVERETT...BUT BREEZY FOR A FEW HOURS LATE THIS AFTERNOON. SCATTERED
SHOWERS DECREASING OVERNIGHT...PLENTY OF SNOW SHOWERS IN THE
CASCADES THIS EVENING. AT 3 PM SHOWERS WERE MNLY PERSISTING IN
SKAGIT COUNTY AND THE CASCADES. THERE IS A CHANCE THAT THE PSCZ WILL
DEVELOP IN A MORE CLASSIC FASHION A BIT FURTHER SOUTH THIS
EVENING...BUT I HAVE POPS THAT MNLY JUST SHOW THE ACTIVITY PUSHED
INTO THE CASCADES. THE WINTER STORM WARNING FOR THE CASCADES WILL
END AT 9 PM AND MOST OF THE HEAVY SNOW SHOWERS OUGHT TO BE WINDING
DOWN BY THEN. WARM ADVECTION WILL BEGIN MONDAY AS THE NEXT FRONT
ARRIVES...THIS ONE WILL NOT BE PARTICULARLY STRONG...A TYPICAL WARM
OCCLUSION WITH DECENT SSE WINDS AHEAD OF THE FRONT BUT GRADIENTS
BECOMING RATHER LIGHT MONDAY NIGHT AND EARLY TUE AS THE FRONT
DISSIPATES OVER THE AREA. THEN ANOTHER ROUND OF WARM ADVECTION WILL
INCREASE THE CHANCE OF RAIN TUE NITE THRU WED...ALTHOUGH I HAVE THE
HIGHEST POPS ONLY OVR NW WA AND NORTH CASCADES WITH CHANCE POPS
SEATTLE SOUTH BY WED AS THE FRONT HANGS UP OVER MNLY VANCOUVER
ISLAND...THEN SAGS THRU WRN WA WED NITE OR THU. THE SYSTEMS IN THE
WEEK AHEAD ARE NOT ESPECIALLY STRONG AND WITH THE 500MB HEIGHT ONLY
FALLING 100M FROM LATE TUE THRU MIDWEEK IT SEEMS LIKELY TO BE A
CLOUDY DRIPPY WEEK WITH LITTLE IN THE WAY OF EVENTFUL WEATHER. 19
.LONG TERM...I HAVE KEPT THE GRIDS/FCSTS CLOSE TO CLIMO AND DO NOT
SEE ANY WEATHER SYSTEMS THRU SATURDAY THAT LOOK IMPRESSIVE OR
NOTEWORTHY. THE FREEZING LEVEL SHOULD TREND DOWN THRU THE WEEK AFTER
PEAKING ARND 6500FT EARLY IN THE WEEK. AFTER THE WEAK FRONT ON
THANKSGIVING THERE IS ANOTHER FRONT POSSIBLE LATE FRI...A WEAK TROF
AT 500MB BUT THE GFS HARDLY HAS A SURFACE REFLECTION. THE ECMWF IS
STRONGER WITH COLD FRONT BY 12Z FRI...IT SHOWS A SFC LOW DEEPENING A
BIT AS IT MOVES EAST ALONG 40N THURSDAY AND AS THAT SHIFTS INLAND BY
FRIDAY MORNING SOMEWHERE EAST OF THE CASCADES THERE IS FAIRLY STRONG
ONSHORE FLOW INTO WRN WA. THEN...IF THE GLOBAL MODELS ARE RIGHT HIGH
PRES BUILDS OVER THE PACNW FOR NEXT WEEKEND. 19
&&
.HYDROLOGY...THE ONLY CURRENT RIVER FLOOD PROBLEM IS THE SKOKOMISH
RIVER. IT IS JUST ABOVE FLOOD STAGE THIS AFTERNOON AND WILL LIKELY
REMAIN ABOVE FLOOD STAGE INTO MONDAY MORNING AS WATER IS RELEASED
FROM CUSHMAN DAM #2. THE SYSTEM WHICH WILL MOVE THROUGH WESTERN
WASHINGTON MONDAY AFTERNOON AND EVENING IS NOT A FLOOD-PRODUCING
RAIN SYSTEM BUT IT IS A WARM FRONT...SO RIVERS RECEDING WILL
PROBABLY STOP RECEDING AND OLYMPIC RIVERS MIGHT TREND UP FOR A DAY.
THE FRONTAL SYSTEM WED NITE OR THU AND THE CDFNT LATE IN THE WEEK
LOOK RATHER WEAK AND AS IF THEY ARE MOVING INTO A MEAN RIDGE
POSITION. THE SNOW LEVEL WILL PROBABLY TREND DOWN THRU THE WEEK
AFTER PEAKING TUE OR WED. THE BAROCLINIC ZONE THAT GETS HUNG UP ON
VANCOUVER ISLAND WED IS WORTH WATCHING BUT AT THIS TIME I DO NOT SEE
A RISK FOR RIVER FLOODING AND FLOODING IS NOT EXPECTED ON THE GREEN
RIVER IN THE WEEK AHEAD. 19
&&
.AVIATION...STRONG WESTERLY FLOW ALOFT THIS EVENING WILL WEAKEN
OVERNIGHT AS HIGH PRES BUILDS OVER WA. THE ATMOSPHERE WILL REMAIN
STABLE WIND DECREASING MOISTURE AS ONSHORE FLOW WEAKENS. IF PARTIAL
CLEARING DEVELOPS...SHELTERED VALLEYS MAY SEE SOME FOG OVERNIGHT AND
MON MORNING. HOWEVER...A LIGHT BREEZE OVERNIGHT WILL PROBABLY KEEP
WIDESPREAD FOG FROM FORMING.
A CONVERGENCE ZONE WILL LINGER OVER WRN SKAGIT/SNOHOMISH COUNTY THIS
EVENING BEFORE DISSIPATING. SHOWERS AND LOWER CIGS COULD TEMPORARILY
AFFECT KPAE...BUT THE CONVERGENCE ZONE IS NOT EXPECTED TO SAG SOUTH
INTO KING COUNTY.
MOISTURE WILL INCREASE AT ALL LEVELS ON MON AS A FRONT BRINGS RAIN
TO THE COAST DURING THE MORNING...SPREADING INLAND IN THE AFTERNOON.
LIGHT WLY FLOW ALOFT EARLY WILL BECOME STRONG SW FLOW BY LATE
MORNING AS THE FRONT APPROACHES. THE FRONT WILL WEAK CONSIDERABLY AS
IT PUSHES THROUGH PUGET SOUND SOMETIME EARLY MON EVENING.
KSEA...FINALLY SEEING SOME IMPROVEMENT IN CIGS LATE THIS AFTERNOON.
THE LOWER STRATUS DECK SHOULD SCATTER SHORTLY WITH THE 5K FT DECK
POSSIBLY SCATTERING LATER THIS EVENING. MID AND HIGH CLOUDS WILL
INCREASE TOWARD MON MORNING AS THE NEXT SYSTEM OFFSHORE MOVES
CLOSER. THERE SHOULD BE ENOUGH SLY BREEZE TO PREVENT FOG. DTM
&&
.MARINE...ONSHORE FLOW IS STILL STRONG ENOUGH TO WARRANT GALES FOR
THE COAST AND STRAIT. WILL EXTEND THESE THROUGH 9PM THIS EVENING. A
SMALL CRAFT IS UP FOR REMAINING WATERS THIS EVENING. GRADIENTS EASE
LATER THIS EVENING WITH WINDS BELOW 20 KT ACROSS MOST THE WATERS BY
MIDNIGHT.
ANOTHER FRONT WILL BRING POSSIBLE GALES TO THE COAST LATER MON AND
MON EVENING. MODELS KEEP WINDS AT 30 KT OR LESS ACROSS THE NRN
INLAND WATERS WITH MARGINAL SMALL CRAFT IN THE SOUND. THE FRONT
DISSIPATES AS IT PUSHES INLAND MON EVENING SO A STRONG WLY SURGE OF
WIND IN THE STRAIT IS NOT EXPECTED. DTM
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...A FLOOD WARNING REMAINS IN EFFECT FOR THE SKOKOMISH RIVER
IN MASON COUNTY.
A WINTER STORM WARNING REMAINS EFFECT FOR THE CASCADES TIL 9 PM.
A HIGH SURF ADVISORY IS IN EFFECT FOR THE COAST TIL 9 PM.
PZ...GALE WARNING COAST AND THE ENTIRE STRAIT OF JUAN DE FUCA
THROUGH 9 PM PST.
.SMALL CRAFT ADVISORY UNTIL 9 PM PST REMAINING WATERS.
$$
WWW.WEATHER.GOV/SEATTLE
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.
000
FXUS66 KOTX 222253
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
253 PM PST SUN NOV 22 2009
.SYNOPSIS...
THE STRONG LOW PRESSURE SYSTEM BRINGING WIDESPREAD SNOW AND RAIN
TO THE INLAND NORTHWEST WILL TRACK OUT OF THE REGION
OVERNIGHT...BRINGING IMPROVING CONDITIONS TO ALL LOCATIONS. A
RIDGE WILL THEN BEGIN TO BUILD OVER THE PACIFIC NORTHWEST AND
PERSIST THROUGH THANKSGIVING. DESPITE THE PRESENCE OF THE
RIDGE...A WEAK WARM FRONT WILL BRING A CHANCE OF LIGHT RAIN AND
SNOW MAINLY TO LOCATIONS NORTH OF I90. AFTER THANKSGIVING...THE
RIDGE WILL BREAK DOWN ALLOWING A STRONG COLD FRONT TO CROSS THE
AREA POSSIBLY BRINGING A RETURN TO WINTRY WEATHER.
&&
.DISCUSSION...
TONIGHT...WINTER HIGHLIGHTS WILL REMAIN IN EFFECT ACROSS THE
CENTRAL PANHANDLE MTNS AS WELL AS THE IDAHO PALOUSE AND NORTHERN
BLUE MTNS AS SATELLITE AND RADAR IMAGERY CONTINUE TO ILLUSTRATE A
TIGHT CIRCULATION AND MODERATE TO LOCALLY HEAVY PRECIPITATION
BANDS MOVING THROUGH. SNOW ACCUMULATIONS AS OF 2PM PST LOOK TO BE
AT AND ABOVE MAINLY 2500 BUT ANTICIPATE THIS TO LOWER SLIGHTLY
WITH SUNSET AND LOSS OF DAYTIME HEATING. ALTHOUGH SNOW IS FALLING
IN THE WASHINGTON PALOUSE...NO WINTER HIGHLIGHTS ARE EXPECTED AT
THIS TIME. THIS INCLUDES THE PULLMAN AREA WHICH HAS BEEN REPORTING
MOD-HVY SNOW THE LAST FEW HOURS...HOWEVER ASOS AMONGST SPOTTERS IN
THE AREA ARE REPORTING WELL ABOVE FREEZING TEMPERATURES AND CAMS
ONLY SUGGESTING SMALL ACCUMULATIONS OF SLUSH UNDER THE HEAVIEST
BANDS. THEREFORE...THE AREA OF FOCUS FOR THE NEXT 6 HOURS WILL BE
IN THE IDAHO PALOUSE AND SOUTHERN PANHANDLE MTNS WHERE STRONG
SOUTHWEST UPSLOPE FLOW WILL PERSIST THROUGH 06Z BEFORE TAPERING
OFF TO ISOLATED LIGHT SHWRS AS THE MIDLEVEL CIRCULATION JUMPS INTO
WESTERN MT AND UPPER-LEVELS BEGIN TO DRY AND QUICKLY STABILIZE.
FURTHER SOUTH AND WEST...FLOW IN THE MID LEVELS CONTINUES TO SHOW
MORE OF A WESTERLY COMPONENT AND THIS IS SUPPORTING STRONG UPSLOPE
INTO THE NORTHERN BLUE MTNS. A SPOTTER IN THE ANATONE
AREA...NEARLY 3800` HAS REPORTED AS MUCH AS 7 INCHES SINCE 9PM
LAST NIGHT.
AS TEMPERATURES COOL WITH SUNSET...THERE IS SOME CONCERN THAT
THIS AFTERNOON`S PRECIPITATION WHICH APPEARED TO MELT ON ROADWAYS
ACROSS ALL LOCATIONS BELOW 2000` TO REFREEZE WITH AREAS OF BLACK
ICE FORMING...SO EVEN WITHOUT WINTER HIGHLIGHTS IN
EFFECT...RESIDENTS SHOULD PLAN FOR ICY CONDITIONS...ESPECIALLY IN
THE EARLY MORNING HOURS JUST PRIOR TO SUNRISE.
WITH A SLIGHTLY MORE SOUTHERN STORM TRACK...WE DO NOT EXPECT
HE HIGH WINDS ACROSS OUR LOWER BASIN AND PALOUSE BUT STILL IN
THE BREEZY CATEGORY THROUGH THE NIGHT. THIS SHOULD PREVENT ANY FOG
FROM FORMING OUTSIDE THE PROTECTED VALLEYS BUT WILL LIKELY PROMOTE
LOW STRATUS AND DRIZZLE ACROSS AREAS OF SPOKANE AND PULLMAN
THROUGH THE NT. FURTHER NORTH...INCLUDING COLVILLE...DEER
PARK...AND SANDPOINT...HAVE LEFT PATCHY FOG IN THE FORECAST WITH
LIGHT WINDS AND EARLY MORNING CLEARING ANTICIPATED./SB
MONDAY THROUGH WEDNESDAY...LOOKS LIKE THE WEATHER WILL FINALLY TURN A BIT
MORE TRANQUIL DURING THIS PERIOD. A LOOK AT THE UPPER LEVEL
5-WAVE CHARTS REVEALS THE FORMATION OF A LONGWAVE RIDGE OVER THE
PACNW. WHILE LONGWAVE RIDGES TYPICALLY BRING DRY WEATHER...THIS
RIDGE WILL BE A LITTLE DIRTY WHICH SUBSEQUENTLY ALLOWS A COUPLE
WEAK FRONTS TO NEAR THE REGION. JUST HOW STRONG THESE FRONTS WILL
BE AND HOW MUCH MOISTURE THEY WILL CARRY WILL BE THE BIG QUESTION.
BEFORE THE FIRST FRONT ENTERS THE PICTURE HOWEVER WE WILL STILL DEAL WITH
RESIDUAL MOISTURE FROM TODAYS TROF. BY MIDDAY ALL SHORT RANGE
MODELS TAKE THE TROF INTO CENTRAL MONTANA. WEAK UPSLOPE SW FLOW
COULD PRODUCE A FEW SHOWERS OVER THE IDAHO PANHANDLE...HOWEVER
THROUGH THE DAY...THE POTENTIAL INSTABILITY BECOMES QUITE SHALLOW
AND BY AFTERNOON IS LIKELY TOO SHALLOW TO SUPPORT SHOWERS.
MEANWHILE THE AFOREMENTIONED FRONT BEGINS TO PUSH ONTO THE COAST
BY AFTERNOON. THE CURRENT POSITION OF THE WARM FRONT IS JUST WEST
OF 130W AND WAS HANDLED WELL BY ALL MODELS AS OF 18Z.
WHAT HAPPENS AFTER THE FRONT PUSHES ONTO THE COAST AGAIN WILL BE THE
BIG QUESTION. ALL THE MODELS TAKE TO FRONT AND BEGIN TO NUDGE IT
THROUGH THE MEAN UPPER LEVEL RIDGE POSITION...ALL THE WHILE
TRANSITIONING FROM ITS CURRENT N-S ORIENTATION TOWARD MORE OF A
ZONAL E-W ORIENTATION. THIS MAKES SENSE GIVEN THE MEAN RIDGE
POSITION...BUT HOW FAR SOUTH WILL THE FRONT SURGE AND HOW LONG
WILL IT HOLD TOGETHER. THE ECMWF AND GFS SOLUTIONS ARE THE WEAKEST
AND DRIEST SOLUTIONS AND KEEP MOST IF NOT ALL PRECIPITATION OVER
THE FAR NORTHERN ZONES THROUGH EARLY TUESDAY MORNING. QPF AMOUNTS
ARE FAIRLY LIGHT. MEANWHILE THE NAM SOLUTION IS DECIDEDLY WETTER
AND MORE AGGRESSIVE IN PUSHING THE FRONT SOUTH ON TUESDAY. NOT
SURPRISINGLY THE NAM HAS THE SUPPORT OF THE SREF
SOLUTIONS...HOWEVER ITS HARD TO ARGUE WITH THE GFS AND
ECMWF...ESPECIALLY SINCE THEY AGREE SO WELL WITH ONE ANOTHER. THE
CANADIAN MODEL IS A LITTLE WETTER...BUT IT TOO KEEPS MOST OF THE
PRECIPITATION OVER THE FAR NORTHERN ZONES. WE WILL STICK WITH THE
ECMWF/GFS BLEND AND KEEP LIGHT QPF AMOUNTS FIXED OVER THE FAR
NORTHERN ZONES. GIVEN THE PERSISTENT WESTERLY FLOW IN THE 850-700
MB LAYER...WE WILL PUT DRIER RAIN SHADOW AFFECTS IN THE LEE OF THE
CASCADES. EVEN THE WETTEST QPF AMOUNTS FROM THE GFS AND ECMWF
SUGGEST SNOW AMOUNTS OVER ALL LOCATIONS WOULD BE AN INCH OR LESS.
THROUGH TUESDAY NIGHT AND WEDNESDAY...THE UPPER LEVEL RIDGE AMPLIFIES
EVEN FURTHER...PUSHING THE WARM FRONT NORTH OF THE CANADIAN
BORDER AND WARMING UP MOST LOCATIONS. SNOW LEVELS BY WEDNESDAY
WILL SURGE ABOVE 5000 FEET OVER THE SOUTHERN 2/3RDS OF THE
CWA...WITH LEVELS BETWEEN 2000-3000 FT ACROSS THE FAR NORTH. BY
LATE WEDNESDAY...THE RIDGE AXIS BEGINS TO SHIFT A LITTLE
EAST...ALLOWING THE TRAILING COLD FRONT TO NEAR THE CASCADES. THE
GFS AND ECMWF SOLUTIONS BRING SOME PRECIPITATION TO THE NORTH
CASCADE CREST LATE IN THE DAY...BUT THE FOCUS FOR PRECIPITATION
WILL LIKELY STILL LIE WEST OF THE CREST. MEANWHILE THE NAM AND
SREF SOLUTIONS CONTINUE THEIR WET TRENDS AND SPILL LIGHT TO
MODERATE PRECIPITATION OVER THE NORTHERN TIER OF ZONES. A DPROG/DT
FROM BOTH THE GFS AND ECMWF SUGGESTS THE TIMING MAY BE SPEEDING UP
JUST A TAD...BUT STILL NOTHING AS FAST OR AS WET AS THE NAM.
GIVEN THE INCREASING STABILIZATION OVER THE INLAND NW...WE SUSPECT
FOG AND STRATUS WILL BECOME MORE EXPANSIVE WITH TIME...HOWEVER IF
THE FRONT IS TRULY AS WET AND AS PROGRESSIVE AS THE NAM
SUGGESTS...THE COVERAGE WILL BE MINIMAL. FX
WEDNESDAY NIGHT THROUGH SUNDAY...AMPLIFIED RIDGING AHEAD OF AN
INCOMING SLOW MOVING/STALLED FRONTAL ZONE DRAPED ALONG THE WEST
SIDE AND APEX OF THE RIDGE REMAINS IN THE VICINITY WEDNESDAY NIGHT
INTO THURSDAY. AS THE FRONT APPROACHES FROM THE WEST THE PART
DRAPED ALONG THE APEX PIVOTS TO THE NORTH AND INTO SOUTHERN
BRITISH COLUMBIA WITH TIME ALLOWING FOR MINOR POPS FOR ANY
RAIN/SNOWFALL ASSOCIATED WITH IT ALONG THE BRITISH COLUMBIA BORDER
AND NEAR THE CASCADE CREST. THE FRONT SWEEPS THROUGH IN A
NEGATIVELY TILTED FASHION THURSDAY NIGHT ALLOWING THE HIGH POPS
FOR RAIN/SNOW ASSOCIATED WITH IT TO SPREAD FROM WEST TO EAST
ACROSS THE FORECAST AREA INTO FRIDAY. WEAK SHORTWAVE RIDGING IN
THE WAKE ALLOWS FOR DECREASING POPS FOR THE WEEKEND...HOWEVER THE
RIDGE ALOFT IS EXTREMELY WEAK...ALMOST FLAT...AND AS SUCH IS MUCH
MORE SUSCEPTIBLE TO NUISANCE SHORTWAVE MIGRATION...THUS POPS ARE
NOT ZEROED OUT BUT ARE SUBSTANTIALLY LOWER IN COMPARISON TO THE
WORKWEEK. /PELATTI
&&
.AVIATION...
DIFFICULT AND LOW CONFIDENCE FORECAST CARE OF DEEP SFC LOW TRACKING
EASTWARD THROUGH XTRM NRN WA. THIS LOW WILL SHIFT EAST OF THE
CASCADE BEFORE 19Z...ENDING THE THREAT OF PCPN FOR KEAT AND KMWH.
OCNL MVFR CIGS COULD STILL PERSIST THRU THAT TIME. THE GREATER
DIFFICULTIES WILL EXIST FROM KGEG-KCOE AS PRESISTENT PCPN IN THE
FORM OF -SN AT KGEG AND KCOE EVENTUALLY TURN TO -RA. THIS SHUD OCCUR
BTWN 21-23Z. THE CHANGEOVER WILL IMPROVE THE VSBYS FM IFR TO
MVFR/VFR. MEANWHILE KSFF SHUD SEE PRIMARILY RAIN AND MVFR/VFR VSBYS.
THE PCPN AT THESE SITES WILL END BEFORE 00Z...THEN THE FOCUS WILL
TURN TO CHANCES OF LIFR CIGS FORMING LATE TONIGHT. THE QUESTION IS
WHEN. FOR NOW WE WILL SAY ARND 11Z...BUT CONFIDENCE IS LOW.
CONDITIONS AT KPUW AND KLWS SHOULD PRIMARLY BE MVFR/VFR WITH OCNLY
-SN AT KPUW. WINDS WILL BE INCREASING HERE AS WELL WITH GUSTS
APPROACHING 30KTS AFT 20Z. FX
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 28 37 31 39 29 41 / 30 10 50 10 0 0
COEUR D`ALENE 30 37 31 40 29 41 / 60 10 60 20 10 10
PULLMAN 29 40 31 42 32 43 / 80 10 30 30 0 0
LEWISTON 33 45 33 48 32 45 / 50 0 10 20 0 0
COLVILLE 30 38 31 38 32 41 / 10 30 70 20 30 10
SANDPOINT 30 36 29 36 29 35 / 30 30 70 30 30 10
KELLOGG 30 33 29 37 32 38 / 90 30 50 30 10 10
MOSES LAKE 25 43 30 44 30 45 / 0 10 20 10 0 0
WENATCHEE 31 42 34 45 33 44 / 10 10 10 10 10 10
OMAK 24 40 31 44 29 44 / 0 50 60 10 30 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR IDAHO
PALOUSE.
WINTER STORM WARNING UNTIL 1 AM PST MONDAY FOR CENTRAL PANHANDLE
MOUNTAINS.
WA...WINTER WEATHER ADVISORY UNTIL 10 PM PST THIS EVENING FOR
NORTHEAST BLUE MOUNTAINS.
&&
$$
[top]
000
FXUS66 KPQR 222217
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
216 PM PST SUN NOV 22 2009
.SYNOPSIS...SHOWERS CONTINUE TO SPREAD OVER THE FORECAST AREA IN COLD
UNSTABLE WESTERLY FLOW ALOFT. HIGH PRES WILL BUILD OVER WESTERN
OREGON LATER TODAY AND TONIGHT. A WARM FRONT OFF THE COAST ON MON
WILL LIFT NE TOWARDS NW OREGON AND WESTERN WA...THEN STALL ON TUE.
WED THE FRONT WILL FINALLY LIFT N INTO WA...BEFORE A COLD FRONT
PUSHES SE THROUGH THE REGION LATE THU.
&&
.SHORT TERM...SATELLITE IMAGERY SHOWS A LARGE AREA OF SHOWERS OVER
THE PACIFIC SPREADING OVER THE FORECAST AREA IN COLD UNSTABLE
WESTERLY FLOW ALOFT. DOPPLER RADAR SHOWS THE SHOWER ACTIVITY
CONTINUING...WITHOUT A LOT OF CHANGES IN INTENSITY...HOWEVER THEY ARE
BECOMING A LITTLE MORE SCATTERED. LIGHTNING DETECTION DATA HAS SHOWN
A FEW LIGHTNING STRIKES AND HAVE HAD A FEW REPORTS OF SMALL HAIL THIS
AFTERNOON. OROGRAPHICS WILL CONTINUE TO WEAKEN THIS AFTERNOON AS H8
FLOW WEAKENS...SO EXPECT SNOW ACCUMULATIONS TO DROP OFF CONSIDERABLY
AND WILL PROBABLY DROP THE WINTER STORM WARNING WITH THE AFTERNOON
PACKAGE. POST FRONTAL SHOWERS DROP OFF QUICKLY TONIGHT...LAST ON THE
N PART OF THE CASCADES.
AN AREA OF WARM AIR ADVECTION SETS UP OVER THE NW PART OF THE
FORECAST AREA MON...AND CONTINUES INTO TUE. A WEAK SHORTWAVE MOVES
ACROSS THE TOP OF THE DEVELOPING UPPER RIDGE TUE...BRINGING THE BEST
CHANCE FOR OVERRUNNING PRECIPITATION TO THE NW PART OF THE AREA ON
MON NIGHT WITH THE SHORT WAVE MOVING THROUGH THE FORECAST AREA
WEDNESDAY.
.LONG TERM...MODELS IN SOME AGREEMENT ON BRINGING A FRONTAL SYSTEM
AND ITS ASSOCIATED UPPER LEVEL TROF THROUGH THE REGION THU/THU NIGHT
FOR A RETURN TO WET WEATHER. AFTER THIS SYSTEM MOVES THROUGH...THE
WEAK HIGH PRES RIDGE REASSERTS ITSELF OVER THE FORECAST
AREA...KEEPING MOST ENERGY NORTH OF FORECAST AREA.
&&
.AVIATION...MOSTLY VFR CONDITIONS WITH PLENTY OF SHOWERS MOST VFR
THOUGH ISOLATED MVFR. SHOWERS SHOULD BEGIN TO TAPER OFF TONIGHT AS
HIGH PRESSURE BUILDS IN. PRESSURE GRADIENT STAYS STRONG ENOUGH TO
KEEP AREA MIXY TONIGHT DIMINISHING ANY CHANCES FOR FOG AND SOUTH
VALLEY MAY BE A LITTLE CLEARER BUT DRY AIR IS FILTERING INTO THE
REGION AND THIS WILL LIKELY KEEP THEM FOG FREE AS WELL. NEXT
SYSTEM BEGINS TO MOVE IN MONDAY AFTERNOON WITH RAIN STARTING AFTER
18Z ON THE COAST.
KPDX AND APPROACHES...VFR FOR THROUGH 12Z EXCEPT FOR ISOLATED MVFR
SHOWERS THEN INCREASING CHANCE FOR MVFR STRATUS MON MORNING AND THEN
THE NEXT FRONT APPROACHES AND WILL LIKELY SEE MVFR CIGS MON
AFTERNOON. WOLFE
&&
.MARINE...SOLID SMALL CRAFT WINDS WILL LET UP TONIGHT AND THEN
INCREASE AGAIN TO NEAR GALE BY TOMORROW MIDDAY WITH GUSTS NEAR 40 KT
BY TOMORROW AFTERNOON. SEAS AT 18 FT AND WILL DROP TONIGHT TO NEAR
11 FT BEFORE BUILDING TO THE MID TEENS ON MONDAY EVENING. WOLFE
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...GALE WATCH MONDAY MORNING THROUGH MONDAY AFTERNOON CAPE
SHOALWATER TO CASCADE HEAD.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS CAPE SHOALWATER TO
FLORENCE THROUGH MONDAY MORNING.
SMALL CRAFT ADVISORY FOR WINDS CAPE SHOALWATER TO
FLORENCE THROUGH MONDAY MORNING.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS
THROUGH MON NIGHT.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KOTX 221911
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1111 AM PST SUN NOV 22 2009
.SYNOPSIS...
A STRONG AND COLD STORM SYSTEM WILL BRING MODERATE TO HEAVY
SNOWFALL OVER MUCH OF THE REGION TODAY. A BRIEF BREAK TONIGHT AND
MONDAY WILL GIVE WAY TO A WEAKER STORM SYSTEM MONDAY NIGHT. THE
THANKSGIVING HOLIDAY WILL LIKELY BE DRY...WITH DETERIORATING
CONDITIONS TOWARD THE END OF THE WORK WEEK.
&&
.DISCUSSION...
AS OF 18Z...WATER VAPOR SHOWING A TIGHT CIRCULATION DIRECTLY OVER
THE BASIN INDICATIVE OF AN OCCLUDED LOW WHICH IS EXPECT TO
CONTINUE TO FILL AND WEAKEN WHILE EJECTING TO EAST THIS AFTERNOON.
LIGHT TO MODERATE DEFORMATION PRECIPITATION STRETCHES FROM SOUTHERN
SPOKANE COUNTY NORTH AND EAST ACROSS THE CENTRAL PANHANDLE AND
NE MTNS OF WASHINGTON. FOR THE MOST PART...WINTER WEATHER
ADVISORIES LOOK TO BE ON TRACK WITH SNOWFALL AMOUNTS RANGING FROM
1 TO 3 INCHES AND ADDITIONAL SNOW ACCUMULATIONS FOR THE REMAINDER
OF THE AFTERNOON WILL GENERALLY NEAR 1-2 INCHES. AS
ANTICIPATED...ELEVATIONS BELOW 2000` ARE BEGINNING TO WARM ABOVE
FREEZING AND CAMS SHOWING A MIX OF RAIN/SNOW WITH WET ROADWAYS.
THIS WAS ALSO THE REASONING BEHIND CANCELLING THE WASHINGTON PALOUSE
ADVISORY EARLY. AS FOR MODELS...GFS/RUC APPEAR TO THE HAVE A BETTER
DEPICTION OF CURRENT PRESSURE FIELDS AND FORECAST WILL LEAN IN
THIS DIRECTION FOR THE REMAINDER OF THE AFTERNOON. AS THE LOW
CONTINUES TO THE EAST...WE SHOULD SEE CONTINUED UPSLOPE
PRECIPITATION INTO THE CENTRAL PANHANDLE WHERE CURRENT WINTER
WEATHER WARNINGS EXIST. WESTERLIES HAVE ALREADY DEVELOPED OVER EAST
SLOPES WHICH IS WHERE HIGHLIGHTS HAVE EXPIRED AND NO ADDITIONAL
ORGANIZED PRECIPITATION IS EXPECTED OUTSIDE THE CASCADE CREST. /SB
&&
.AVIATION...
DIFFICULT AND LOW CONFIDENCE FORECAST CARE OF DEEP SFC LOW TRACKING
EASTWARD THROUGH XTRM NRN WA. THIS LOW WILL SHIFT EAST OF THE
CASCADE BEFORE 19Z...ENDING THE THREAT OF PCPN FOR KEAT AND KMWH.
OCNL MVFR CIGS COULD STILL PERSIST THRU THAT TIME. THE GREATER
DIFFICULTIES WILL EXIST FROM KGEG-KCOE AS PRESISTENT PCPN IN THE
FORM OF -SN AT KGEG AND KCOE EVENTUALLY TURN TO -RA. THIS SHUD OCCUR
BTWN 21-23Z. THE CHANGEOVER WILL IMPROVE THE VSBYS FM IFR TO
MVFR/VFR. MEANWHILE KSFF SHUD SEE PRIMARILY RAIN AND MVFR/VFR VSBYS.
THE PCPN AT THESE SITES WILL END BEFORE 00Z...THEN THE FOCUS WILL
TURN TO CHANCES OF LIFR CIGS FORMING LATE TONIGHT. THE QUESTION IS
WHEN. FOR NOW WE WILL SAY ARND 11Z...BUT CONFIDENCE IS LOW.
CONDITIONS AT KPUW AND KLWS SHOULD PRIMARLY BE MVFR/VFR WITH OCNLY
-SN AT KPUW. WINDS WILL BE INCREASING HERE AS WELL WITH GUSTS
APPROACHING 30KTS AFT 20Z. FX
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 41 27 37 30 40 31 / 100 10 20 50 20 10
COEUR D`ALENE 37 29 36 30 41 33 / 100 20 20 60 20 10
PULLMAN 39 29 39 30 43 33 / 100 20 10 40 30 0
LEWISTON 47 34 45 32 49 35 / 80 10 10 20 20 0
COLVILLE 38 31 37 29 41 34 / 100 10 50 70 20 20
SANDPOINT 37 30 35 28 38 31 / 100 20 50 70 30 10
KELLOGG 37 29 32 29 40 32 / 100 70 20 60 30 10
MOSES LAKE 46 23 42 27 45 30 / 70 0 20 30 10 0
WENATCHEE 46 29 42 30 45 33 / 90 10 30 40 10 0
OMAK 45 23 38 27 43 30 / 100 0 70 80 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WINTER WEATHER ADVISORY UNTIL 10 PM PST THIS EVENING FOR
NORTHERN PANHANDLE.
WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR IDAHO
PALOUSE.
WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR COEUR
D`ALENE AREA.
WINTER STORM WARNING UNTIL 1 AM PST MONDAY FOR CENTRAL PANHANDLE
MOUNTAINS.
WA...WINTER WEATHER ADVISORY UNTIL 10 PM PST THIS EVENING FOR
NORTHEAST BLUE MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
NORTHEAST MOUNTAINS...SPOKANE AREA.
&&
$$
000
FXUS66 KOTX 221805
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1005 AM PST SUN NOV 22 2009
.SYNOPSIS...
A STRONG AND COLD STORM SYSTEM WILL BRING MODERATE TO HEAVY
SNOWFALL OVER MUCH OF THE REGION TODAY. A BRIEF BREAK TONIGHT AND
MONDAY WILL GIVE WAY TO A WEAKER STORM SYSTEM MONDAY NIGHT. THE
THANKSGIVING HOLIDAY WILL LIKELY BE DRY...WITH DETERIORATING
CONDITIONS TOWARD THE END OF THE WORK WEEK.
&&
.DISCUSSION...
TODAY...INCOMING STORM SYSTEM IS STILL ON TRACK FOR A MORNING
WALLOPING ACROSS MOST OF THE REGION. SATELLITE AND RADAR CLEARLY
INDICATE A STRONG AND DYNAMIC NEGATIVELY TILTED TROUGH DRIVING
INTO THE COAST THIS MORNING...WITH THE LOW CENTER NEAR HOQUIAM AND
ASTORIA AT 2AM THIS MORNING. LATEST MODELS HAVE SETTLED IN REASONABLE
AGREEMENT WITH THE TRACK OF THIS LOW...EJECTING INLAND AND
WEAKENING SLIGHTLY AS IT MOVES NORTHEAST THROUGH THE NORTHERN
REACHES OF THE FORECAST AREA TODAY. A FRONTAL COMPLEX APPARENTLY
CONSISTING OF A WARM FRONT FOLLOWED BY A STRONG COLD OCCLUDED
FRONT WILL PRODUCE 3 TO 5 HOURS OF MODERATE AND OCCASIONALLY HEAVY
PRECIPITATION AS IT PUSHES THROUGH. CURRENT OBSERVATIONS SUGGEST
TEMPERATURE/DEW POINT SPREADS ARE SUFFICIENT TO ALLOW WET BULB
COOLING WELL INTO THE ACCUMULATING SNOW ZONE AT REGIONAL
OBSERVATION SITES ABOVE 2000 FEET ELEVATION WHEN THE FRONTAL
PRECIPITATION GETS UNDERWAY. SO...FOR THIS MORNING THE MAIN STORY
IS THE SNOW POTENTIAL. CURRENT HIGHLIGHTS LOOK PLAUSIBLE AND
WILL NOT BE CHANGED. OVER THE WESTERN ZONES AND CASCADES A 3 TO 5
HOUR PERIOD OF MODERATE SNOW AND LOWER VALLEY WET SNOW OR RAIN MIX
WILL OCCUR THIS MORNING BEFORE ABRUPTLY TAPERING OFF TO SHOWERS BY
MID-MORNING AS STRONG WESTERLY FLOW BEHIND THE LOW CENTER ALLOWS A
RAIN SHADOW EFFECT. OVER THE EASTERN ZONES RELATIVELY BENIGN
CONDITIONS WILL SHARPLY DETERIORATE INTO A PERIOD OF MODERATE AND
OCCASIONALLY HEAVY SNOW STARTING JUST BEFORE DAWN AND LASTING
UNTIL 9 OR 10 AM BEFORE TAPERING OFF TO SHOWERS. ASSUMING A
PROBABLE 1/2 TO 1 INCH PER HOUR OF SNOW ACCUMULATION FOR A FEW
HOURS AT AND IMMEDIATELY BEHIND THE FRONT...CURRENT FORECAST OF
WIDESPREAD 2 TO 4 INCHES ABOVE 2000 FEET IN EASTERN WASHINGTON AND
A COUPLE MORE INCHES IN IDAHO STILL LOOKS INDUBITABLY
PLAUSIBLE...WITH HIGHER AMOUNTS IN THE MOUNTAINS. THIS AFTERNOON
POST FRONTAL WINDS WILL KICK IN MAKING FOR A WINDY AND GUSTY
AFTERNOON AT ALL LOCATIONS. AT THIS TIME IT APPEARS THE
GRADIENT...WHILE TIGHTENING DRAMATICALLY WILL NOT BE SUFFICIENT
FOR SUSTAINED WIND ADVISORY CRITERIA...AND GUST POTENTIAL WILL
PROBABLY BE IN THE 30 TO 40 MPH RANGE ON EXPOSED TERRAIN THIS
AFTERNOON...AGAIN NOT QUITE WIND ADVISORY CRITERIA BUT CLOSE.
TODAYS HIGH TEMPERATURES SHOULD RECOVER TO WELL ABOVE FREEZING
LATE TODAY AS A STRONGLY MIXED AIR MASS ALLOWS ADIABATIC
COMPRESSIONAL WARMING INTO THE UPPER 30S TO LOW 40S AT MANY LOWER
ELEVATION LOCATIONS.
TONIGHT A GENERAL IMPROVEMENT IN CONDITIONS EXPECTED AS THE
OFFENDING WEATHER SYSTEM BOLTS INTO MONTANA AND ALBERTA. EXCEPT
FOR LINGERING MOUNTAIN OROGRAPHIC SNOW SHOWERS...MAINLY DRY
CONDITIONS IN THE BASIN ARE EXPECTED WITH AN ISOLATED ROGUE LIGHT
SNOW SHOWER OR TWO OVER THE RISING TERRAIN OF THE EASTERN BASIN. A
SHARP SHORT WAVE RIDGE WILL BUILD OVER THE REGION WITH DECREASING
WINDS AS A SURFACE HIGH PRESSURE BECOMES ESTABLISHED OVER IDAHO.
FOR MONDAY THE SHORT WAVE RIDGE WILL BEGIN TO BE CRESTED BY
INCREASING MOISTURE FROM THE NEXT SYSTEM. INCREASING AND
THICKENING MID AND HIGH LEVEL CLOUDS WILL CHARACTERIZE THE SKY
COVER...WITH AN INCREASING POSSIBILITY OF LIGHT SNOW ONCE AGAIN
BEGINNING OVER THE WESTERN ZONES BY LATE AFTERNOON. /FUGAZZI
FOR MONDAY NIGHT AND TUESDAY...A WEAK STORM WILL RIPPLE ACROSS THE
NORTHERN TIER ZONES. CURRENTLY...THIS MOISTURE PLUME IS SEEN
CROSSING 50/160W AND HEADING OVER THE SHORTWAVE RIDGE IN THE GULF
OF ALASKA. THE MODELS WEAKEN THE LOW CENTER AND PULL IT NORTH
ACROSS THE YUKON...AND THEN DRAG THE REMAINS OF THE FRONTAL
BOUNDARY ACROSS THE WASHINGTON CASCADES BEFORE FALLING APART
ACROSS THE NORTHEAST WASHINGTON. HIGH PRESSURE BUILDS IN QUICKLY
BEHIND THIS FEATURE...LEANING TOWARD A LIGHT PRECIPITATION EVENT
ESPECIALLY FOR AREAS NORTH OF HIGHWAY 2. ALTHOUGH TEMPERATURES WILL
DROP TO NEAR FREEZING WITH MAINLY SNOW IN THE HIGHER VALLEYS AND
MOUNTAINS...COOLING BEHIND THE FRONT WILL BE MINIMAL AND TEMPERATURES
WILL GRADUALLY WARM ON TUESDAY.
THEN TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...THE UPPER LEVEL RIDGE
BUILDS...BRINGING WARMER AND SOMEWHAT DRIER AIR IN FROM THE SOUTH.
YET WITH THE TOP OF RIDGE IN CLOSE PROXIMITY TO THE CANADIAN
BORDER...ANTICIPATE A DIRTY RIDGE SCENARIO AND MID AND HIGH LEVEL
MOISTURE SPREADING ACROSS MUCH OF THE FORECAST AREA. IN
ADDITION...WEAK ISENTROPIC LIFT WILL LEAD TO LIGHT SHOWERS OVER
THE NORTHERN MOUNTAINS THROUGH MID WEEK. THE RIDGE IS EXPECTED TO
AMPLIFY WHICH WILL PUSH MOST OF THE MOISTURE NORTH OF THE REGION
BY WEDNESDAY.
FOR THANKSGIVING INTO FRIDAY...MADE SOME CHANGES TO THE HOLIDAY
FORECAST. LATEST MODEL RUN WITH THE GFS AND ECWMF KEEP THE UPPER
LEVEL RIDGE STRONG OVER THE INLAND NORTHWEST AND SLOW DOWN THE NEXT
STORM SYSTEM. SO OPTED TO DRY OUT MUCH OF THE REGION ON THANKSGIVING
DAY...AND THEN SHOW A GRADUAL BREAK DOWN OF THE RIDGE THURSDAY NIGHT
INTO FRIDAY WITH A SLOW MOVING COLD FRONT. EMPHASIZED THE BEST
CHANCE OF PRECIPITATION FOR NORTHEAST WASHINGTON AND NORTH IDAHO FOR
FRIDAY WHEN THE OROGRAPHIC AND THE SYNOPTIC LIFT COMBINE.
THE WEEKEND...COOLER AND UNSETTLED WEATHER IS FORECAST AS AN
UPPER LEVEL TROUGH MOVING THROUGH THE REGION...FOLLOWED BY AN
UNSTABLE NORTHWEST TO NORTH FLOW OVER THE INLAND NORTHWEST. WILL
LEAN TOWARD POTENTIAL FOR MAINLY MOUNTAIN SHOWERS. /RFOX.
&&
.AVIATION...
DIFFICULT AND LOW CONFIDENCE FORECAST CARE OF DEEP SFC LOW TRACKING
EASTWARD THROUGH XTRM NRN WA. THIS LOW WILL SHIFT EAST OF THE
CASCADE BEFORE 19Z...ENDING THE THREAT OF PCPN FOR KEAT AND KMWH.
OCNL MVFR CIGS COULD STILL PERSIST THRU THAT TIME. THE GREATER
DIFFICULTIES WILL EXIST FROM KGEG-KCOE AS PRESISTENT PCPN IN THE
FORM OF -SN AT KGEG AND KCOE EVENTUALLY TURN TO -RA. THIS SHUD OCCUR
BTWN 21-23Z. THE CHANGEOVER WILL IMPROVE THE VSBYS FM IFR TO
MVFR/VFR. MEANWHILE KSFF SHUD SEE PRIMARILY RAIN AND MVFR/VFR VSBYS.
THE PCPN AT THESE SITES WILL END BEFORE 00Z...THEN THE FOCUS WILL
TURN TO CHANCES OF LIFR CIGS FORMING LATE TONIGHT. THE QUESTION IS
WHEN. FOR NOW WE WILL SAY ARND 11Z...BUT CONFIDENCE IS LOW.
CONDITIONS AT KPUW AND KLWS SHOULD PRIMARLY BE MVFR/VFR WITH OCNLY
-SN AT KPUW. WINDS WILL BE INCREASING HERE AS WELL WITH GUSTS
APPROACHING 30KTS AFT 20Z. FX
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 41 27 37 30 40 31 / 100 10 20 50 20 10
COEUR D`ALENE 37 29 36 30 41 33 / 100 20 20 60 20 10
PULLMAN 39 29 39 30 43 33 / 100 20 10 40 30 0
LEWISTON 47 34 45 32 49 35 / 80 10 10 20 20 0
COLVILLE 38 31 37 29 41 34 / 100 10 50 70 20 20
SANDPOINT 37 30 35 28 38 31 / 100 20 50 70 30 20
KELLOGG 37 29 32 29 40 32 / 100 70 20 60 30 10
MOSES LAKE 46 23 42 27 45 30 / 70 0 20 30 10 0
WENATCHEE 46 29 42 30 45 33 / 90 10 30 40 10 0
OMAK 45 23 38 27 43 30 / 100 0 70 80 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WINTER WEATHER ADVISORY UNTIL 10 PM PST THIS EVENING FOR
NORTHERN PANHANDLE.
WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR IDAHO
PALOUSE.
WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR COEUR
D`ALENE AREA.
WINTER STORM WARNING UNTIL 1 AM PST MONDAY FOR CENTRAL
PANHANDLE MOUNTAINS.
WA...WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
NORTHEAST MOUNTAINS...SPOKANE AREA.
WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR EAST
SLOPES NORTHERN CASCADES.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR OKANOGAN
HIGHLANDS...OKANOGAN VALLEY.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR UPPER COLUMBIA
BASIN...WATERVILLE PLATEAU.
WINTER WEATHER ADVISORY UNTIL 10 PM PST THIS EVENING FOR
NORTHEAST BLUE MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
WASHINGTON PALOUSE.
&&
$$
000
FXUS66 KSEW 221750
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
910 AM PST SUN NOV 22 2009
.SYNOPSIS...A LOW PRESSURE CENTER OVER WASHINGTON WILL SHIFT INLAND
AND HIGHER PRESSURE WILL BUILD INTO THE REGION TODAY. THIS WILL GIVE
RATHER BLUSTERY WINDS...ESPECIALLY ON THE COAST AND IN THE STRAIT OF
JUAN DE FUCA. SNOW SHOWERS WILL BE HEAVY AT TIMES IN THE MOUNTAINS.
A WARM FRONT WILL MOVE THROUGH THE AREA MONDAY AND MONDAY
NIGHT...FOLLOWED BY ANOTHER WARM FRONTAL SYSTEM LATER IN THE WEEK.
&&
.SHORT TERM...ANOTHER BLUSTERY DAY FOR WRN WA...WINDY ON THE COAST
AND THRU THE CHEHALIS GAP...AND WESTERLY GALES SHUD DVLP IN THE
STRAIT BY NOON. THE WIND ADVISORY SHUD PROBABLY BE EXTENDED NORTH
THRU THE METRO AREA AND HOOD CANAL FOR RATHER BLUSTERY WEATHER DVLPG
THRU THE MORNING AND PEAKING MIDDAY. WHEN I DO THAT I WILL HAVE THEM
ALL EXPIRE AT 3PM. SHOULD BE A GOOD PSCZ WIND PATTERN BY
AFTERNOON...SO AFTER THE SURGE OF SW 20-30MPH WINDS THIS MORNING
THRU THE SEATTLE METRO AREA THE WIND WILL SETTLE DOWN AS THE PSCZ
SETS UP. THE WINTER STORM WARNING FOR THE CASCADES PROBABLY NEEDS A
REFRESH AS WELL...IT EXPIRES AT 1PM AND AS THE WESTERLY OROGRAPHIC
SNOW KICKS IN BY AFTERNOON SO THAT NEED TO BE EXTENDED INTO THE
EARLY EVENING. WINDS IN THE CASCADE PASSES INCREASING TO WESTERLY
20-30 MPH BY AFTERNOON AND GUSTS TO 50 ON THE RIDGETOPS...A LOT LESS
THAN THE PEAK WINDS OVERNIGHT: AT THE VERY TOP OF CRYSTAL MOUNTAIN
ARND 1AM LAST NITE STRONG SE WINDS OF 50 MPH GUSTED TO ARND
95MPH...QUITE A WINTER STORM UP HIGH. THE SYSTEM FOR MONDAY WILL BE
WEAKER AND WARMER...ALTHOUGH IT WILL PROBABLY MUSTER SSE GALES JUST
AHEAD OF THE FRONT OVER THE COASTAL WATERS MON MORNING....BY MON
NITE THE GRADIENT OVER WRN WA IS QUITE LIGHT. IN FACT THE WEATHER
PATTERN NEXT WEEK LOOKS A LOT LIKE WHAT EL NINO IS SUPPOSED TO
BRING...WARMTH AND FAIRLY WEAK SYSTEMS. 19
.LONG TERM...ANOTHER WARM FRONT WILL BRUSH THE NORTHWEST CORNER OF
THE AREA AS IT MOVES INTO BRITISH COLUMBIA. THE TRAILING COLD FRONT
WILL DRAG SLOWLY ACROSS THE FORECAST AREA WEDNESDAY NIGHT THROUGH
THURSDAY FOLLOWED BY ITS UPPER TROUGH THURSDAY NIGHT AND FRIDAY.
MCDONNAL
&&
.HYDROLOGY...THE ONLY CURRENT RIVER FLOOD PROBLEM IS THE SKOKOMISH
RIVER. IT IS JUST ABOVE FLOOD STAGE THIS MORNING AND WILL LIKELY
REMAIN ABOVE FLOOD STAGE INTO MONDAY. THIS IS DUE PRIMARILY TO
RELEASES OF WATER FROM CUSHMAN DAM #2. THE SYSTEM MOVING THROUGH
WESTERN WASHINGTON TODAY IS NOT A FLOOD-PRODUCING RAIN SYSTEM BUT
RATHER A HEAVY MOUNTAIN SNOW SYSTEM.
THE FRONTAL SYSTEMS EXPECTED TO ARRIVE DURING THE COMING WEEK WILL
BE ACCOMPANIED BY HIGHER SNOW LEVELS -- PROBABLY IN THE 5000 TO 7000
FT RANGE. ONE FRONT IS FORECAST TO MOVE THROUGH MONDAY AND MONDAY
NIGHT WITH ANOTHER SYSTEM MOVING SLOWLY THROUGH WEDNESDAY NIGHT
THROUGH THURSDAY NIGHT. THEY ARE NOT EXPECTED TO PRODUCE ENOUGH
PRECIPITATION TO CREATE FLOODING CONCERNS.
NO FLOODING IS EXPECTED AT ANY TIME ON THE GREEN RIVER.
&&
.AVIATION...SURFACE LOW PRES THAT MOVED ONSHORE EARLIER THIS MORNING
IS NOW SHIFTING INTO WRN WA ALONG WITH THE UPPER TROUGH. ONSHORE
FLOW WILL PERSIST TODAY WITH STRONG WLY FLOW ALOFT. THE ATMOSPHERE
WILL REMAIN MOIST AND SLIGHTLY UNSTABLE THIS MORNING WITH WRAP
AROUND MOISTURE KEEPING LOWER CIGS AND RAIN AROUND A LITTLE LONGER
THAN EXPECTED. CIGS SHOULD IMPROVE TO VFR AFTER 21Z WITH DECREASING
MOISTURE. WITH PARTIAL CLEARING TONIGHT...EXPECT AREAS OF FOG TO
FORM...MOSTLY IN FAVORED SHELTERED VALLEYS.
A PUGET SOUND CONVERGENCE ZONE /PSCZ/ WILL DEVELOP N OF THE
SNOHOMISH/KING COUNTY BORDER LATER THIS MORNING AND THEN MOVE S
DURING THE AFTERNOON...BECOMING QUASISTATIONARY OVER THE N CENTRAL
PUGET SOUND. AT THIS TIME...IT LOOKS LIKE THE PSCZ WILL REMAIN N OF
KBFI. WINDS WILL BACK TONIGHT AS THE PRES GRADIENT BECOMES SLY...
THUS EXPECT THE PSCZ TO DRIFT BACK TO THE N AND THEN DISSIPATE LATER
TONIGHT.
KSEA...CIGS 1-2K FT AND VIS 3-5SM MAY HOLD IN A LITTLE LONG THAN
EXPECTED DUE TO WRAP AROUND MOISTURE. STILL EXPECT IMPROVEMENT TO
VFR CONDITIONS BY 21Z. SW WIND 10-15 KT W/ GUSTS TO 30 KT
TODAY...BECOMING S 3-6 KT THIS EVENING. DTM
&&
.MARINE...STRONG ONSHORE FLOW TODAY BEHIND A LOW PRESSURE SYSTEM
WHICH IS NOW SHIFTING INTO ERN WA. GALES ALONG THE COAST SHOULD
CONTINUE THROUGH MOST THE DAY BEFORE EASING. THE WINDS IN THE STRAIT
TOOK A LITTLE LONGER THAN EXPECTED TO COME AROUND WLY...BUT SHOULD
STILL POP UP TO GALE FORCE BY NOON. WINDS HAVE COME UP SLIGHTLY
AROUND PUGET SOUND BUT OBS SO FAR ARE FAR SHORT OF GALES...SO I WILL
KEEP A SMALL CRAFT IN EFFECT TODAY. DTM
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...A FLOOD WARNING REMAINS IN EFFECT FOR THE SKOKOMISH RIVER
IN MASON COUNTY.
A WINTER STORM WARNING REMAINS EFFECT FOR THE CASCADES TODAY.
WIND ADVISORIES ARE IN EFFECT FOR THE STRAIT OF JUAN DE FUCA
AND THE ADMIRALTY INLET AREAS...SOUTHWEST INTERIOR...LOWER
CHEHALIS VALLEY...SEATTLE TACOMA BREMERTON METRO AREA...HOOD
CANAL.
PZ...GALE WARNINGS ARE IN EFFECT FOR ALL WATERS EXCEPT PUGET SOUND
TODAY.
SMALL CRAFT ADVISORY PUGET SOUND TODAY.
A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR ROUGH GRAYS
HARBOR BAR CONDITIONS TIL 4 PM MON.
$$
WWW.WEATHER.GOV/SEATTLE
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.
000
FXUS66 KSEW 221716
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
910 AM PST SUN NOV 22 2009
.SYNOPSIS...A LOW PRESSURE CENTER OVER WASHINGTON WILL SHIFT INLAND
AND HIGHER PRESSURE WILL BUILD INTO THE REGION TODAY. THIS WILL GIVE
RATHER BLUSTERY WINDS...ESPECIALLY ON THE COAST AND IN THE STRAIT OF
JUAN DE FUCA. SNOW SHOWERS WILL BE HEAVY AT TIMES IN THE MOUNTAINS.
A WARM FRONT WILL MOVE THROUGH THE AREA MONDAY AND MONDAY
NIGHT...FOLLOWED BY ANOTHER WARM FRONTAL SYSTEM LATER IN THE WEEK.
&&
.SHORT TERM...ANOTHER BLUSTERY DAY FOR WRN WA...WINDY ON THE COAST
AND THRU THE CHEHALIS GAP...AND WESTERLY GALES SHUD DVLP IN THE
STRAIT BY NOON. THE WIND ADVISORY SHUD PROBABLY BE EXTENDED NORTH
THRU THE METRO AREA AND HOOD CANAL FOR RATHER BLUSTERY WEATHER DVLPG
THRU THE MORNING AND PEAKING MIDDAY. WHEN I DO THAT I WILL HAVE THEM
ALL EXPIRE AT 3PM. SHOULD BE A GOOD PSCZ WIND PATTERN BY
AFTERNOON...SO AFTER THE SURGE OF SW 20-30MPH WINDS THIS MORNING
THRU THE SEATTLE METRO AREA THE WIND WILL SETTLE DOWN AS THE PSCZ
SETS UP. THE WINTER STORM WARNING FOR THE CASCADES PROBABLY NEEDS A
REFRESH AS WELL...IT EXPIRES AT 1PM AND AS THE WESTERLY OROGRAPHIC
SNOW KICKS IN BY AFTERNOON SO THAT NEED TO BE EXTENDED INTO THE
EARLY EVENING. WINDS IN THE CASCADE PASSES INCREASING TO WESTERLY
20-30 MPH BY AFTERNOON AND GUSTS TO 50 ON THE RIDGETOPS...A LOT LESS
THAN THE PEAK WINDS OVERNIGHT: AT THE VERY TOP OF CRYSTAL MOUNTAIN
ARND 1AM LAST NITE STRONG SE WINDS OF 50 MPH GUSTED TO ARND
95MPH...QUITE A WINTER STORM UP HIGH. THE SYSTEM FOR MONDAY WILL BE
WEAKER AND WARMER...ALTHOUGH IT WILL PROBABLY MUSTER SSE GALES JUST
AHEAD OF THE FRONT OVER THE COASTAL WATERS MON MORNING....BY MON
NITE THE GRADIENT OVER WRN WA IS QUITE LIGHT. IN FACT THE WEATHER
PATTERN NEXT WEEK LOOKS A LOT LIKE WHAT EL NINO IS SUPPOSED TO
BRING...WARMTH AND FAIRLY WEAK SYSTEMS. 19
.LONG TERM...ANOTHER WARM FRONT WILL BRUSH THE NORTHWEST CORNER OF
THE AREA AS IT MOVES INTO BRITISH COLUMBIA. THE TRAILING COLD FRONT
WILL DRAG SLOWLY ACROSS THE FORECAST AREA WEDNESDAY NIGHT THROUGH
THURSDAY FOLLOWED BY ITS UPPER TROUGH THURSDAY NIGHT AND FRIDAY.
MCDONNAL
&&
.HYDROLOGY...THE ONLY CURRENT RIVER FLOOD PROBLEM IS THE SKOKOMISH
RIVER. IT IS JUST ABOVE FLOOD STAGE THIS MORNING AND WILL LIKELY
REMAIN ABOVE FLOOD STAGE INTO MONDAY. THIS IS DUE PRIMARILY TO
RELEASES OF WATER FROM CUSHMAN DAM #2. THE SYSTEM MOVING THROUGH
WESTERN WASHINGTON TODAY IS NOT A FLOOD-PRODUCING RAIN SYSTEM BUT
RATHER A HEAVY MOUNTAIN SNOW SYSTEM.
THE FRONTAL SYSTEMS EXPECTED TO ARRIVE DURING THE COMING WEEK WILL
BE ACCOMPANIED BY HIGHER SNOW LEVELS -- PROBABLY IN THE 5000 TO 7000
FT RANGE. ONE FRONT IS FORECAST TO MOVE THROUGH MONDAY AND MONDAY
NIGHT WITH ANOTHER SYSTEM MOVING SLOWLY THROUGH WEDNESDAY NIGHT
THROUGH THURSDAY NIGHT. THEY ARE NOT EXPECTED TO PRODUCE ENOUGH
PRECIPITATION TO CREATE FLOODING CONCERNS.
NO FLOODING IS EXPECTED AT ANY TIME ON THE GREEN RIVER.
&&
.AVIATION...SURFACE LOW PRES THAT MOVED ONSHORE EARLIER THIS MORNING
IS NOW SHIFTING INTO WRN WA ALONG WITH THE UPPER TROUGH. ONSHORE
FLOW WILL PERSIST TODAY WITH STRONG WLY FLOW ALOFT. THE ATMOSPHERE
WILL REMAIN MOIST AND SLIGHTLY UNSTABLE THIS MORNING WITH WRAP
AROUND MOISTURE KEEPING LOWER CIGS AND RAIN AROUND A LITTLE LONGER
THAN EXPECTED. CIGS SHOULD IMPROVE TO VFR AFTER 21Z WITH DECREASING
MOISTURE. WITH PARTIAL CLEARING TONIGHT...EXPECT AREAS OF FOG TO
FORM...MOSTLY IN FAVORED SHELTERED VALLEYS.
A PUGET SOUND CONVERGENCE ZONE /PSCZ/ WILL DEVELOP N OF THE
SNOHOMISH/KING COUNTY BORDER LATER THIS MORNING AND THEN MOVE S
DURING THE AFTERNOON...BECOMING QUASISTATIONARY OVER THE N CENTRAL
PUGET SOUND. AT THIS TIME...IT LOOKS LIKE THE PSCZ WILL REMAIN N OF
KBFI. WINDS WILL BACK TONIGHT AS THE PRES GRADIENT BECOMES SLY...
THUS EXPECT THE PSCZ TO DRIFT BACK TO THE N AND THEN DISSIPATE LATER
TONIGHT.
KSEA...CIGS 1-2K FT AND VIS 3-5SM MAY HOLD IN A LITTLE LONG THAN
EXPECTED DUE TO WRAP AROUND MOISTURE. STILL EXPECT IMPROVEMENT TO
VFR CONDITIONS BY 21Z. SW WIND 10-15 KT W/ GUSTS TO 30 KT
TODAY...BECOMING S 3-6 KT THIS EVENING. DTM
&&
.MARINE...STRONG ONSHORE FLOW TODAY BEHIND A LOW PRESSURE SYSTEM
WHICH IS NOT SHIFTING INTO ERN WA. GALES ALONG THE COAST SHOULD
CONTINUE THROUGH MOST THE DAY BEFORE EASING. THE WINDS IN THE STRAIT
TOOK A LITTLE LONGER THAN EXPECTED TO COME AROUND WLY...BUT SHOULD
STILL POP UP TO GALE FORCE BY NOON. WINDS HAVE COME UP SLIGHTLY
AROUND PUGET SOUND BUT OBS SO FAR ARE FAR SHORT OF GALES...SO I WILL
KEEP A SMALL CRAFT IN EFFECT TODAY. DTM
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...A FLOOD WARNING REMAINS IN EFFECT FOR THE SKOKOMISH RIVER
IN MASON COUNTY.
A WINTER STORM WARNING REMAINS EFFECT FOR THE CASCADES TODAY.
WIND ADVISORIES ARE IN EFFECT FOR THE STRAIT OF JUAN DE FUCA
AND THE ADMIRALTY INLET AREAS...SOUTHWEST INTERIOR...LOWER
CHEHALIS VALLEY...SEATTLE TACOMA BREMERTON METRO AREA...HOOD
CANAL.
PZ...GALE WARNINGS ARE IN EFFECT FOR ALL WATERS EXCEPT PUGET SOUND
TODAY.
SMALL CRAFT ADVISORY PUGET SOUND TODAY.
A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR ROUGH GRAYS
HARBOR BAR CONDITIONS TIL 4 PM MON.
$$
WWW.WEATHER.GOV/SEATTLE
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.
000
FXUS66 KPQR 221639
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
839 AM PST SUN NOV 22 2009
.SYNOPSIS...A STRONG SURFACE LOW OVER WESTERN WASHINGTON THIS MORNING
WILL CONTINUE TO MOVE EAST TODAY AND WEAKEN. HIGH PRES WILL BUILD IN
OVER WESTERN OREGON LATER TODAY AND TONIGHT. A WARM FRONT OFF THE
COAST ON MON WILL LIFT NE TOWARDS NW OREGON AND WESTERN WA....THEN
STALL ON TUE. WED THE FRONT WILL FINALLY LIFT N INTO WA...BEFORE A
COLD FRONT PUSHES SE THROUGH THE REGION THU.
&&
.SHORT TERM...SATELLITE IMAGERY SHOWS THE LOW PRESSURE SYSTEM THAT
CAME ONSHORE OVERNIGHT NEAR WILLAPA BAY IS NOW IN WESTERN WASHINGTON
NEAR 48N 123W. THE ASSOCIATED OCCLUDED FRONT ARCS JUST EAST OF THE
OREGON CASCADES. WINDS OVER THE FORECAST AREA ARE BELOW WARNING
CRITERIA...HOWEVER THERE ARE STILL STRONG WESTERLY WINDS ON THE
BACKSIDE OF THE FRONT WITH WINDS STILL GUSTING IN THE 40S ALONG THE
COAST.
DOPPLER RADAR SHOWING GOOD SHOWER ACTIVITY OVER THE FORECAST AREA
THIS MORNING. CASCADES HAVE ALREADY RECEIVED 8 TO 12 INCHES OF NEW
SNOW OVERNIGHT. STRONG OROGRAPHIC WESTERLY FLOW WILL KEEP SHOWERS
GOING THIS MORNING...AND WILL KEEP THE WINTER STORM WARNING GOING
TODAY. OROGRAPHICS WEAKEN THIS AFTERNOON AS H8 FLOW WEAKENS...SO WE
SHOULD SEE SNOW ACCUMULATIONS DROP OFF CONSIDERABLY THIS AFTERNOON.
POST FRONTAL SHOWERS DROP OFF QUICKLY TONIGHT...LAST ON THE N PART OF
THE CASCADES. AN AREA OF WARM AIR ADVECTION SETS UP OVER THE NW PART
OF THE FORECAST AREA MON...AND CONTINUES INTO TUE. A WEAK SHORTWAVE
MOVES ACROSS THE TOP OF THE DEVELOPING UPPER RIDGE TUE...BRINGING THE
BEST CHANCE FOR OVERRUNNING PRECIPITATION TO THE NW PART OF THE AREA
ON TUE.
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...WEAK HIGH PRES
RIDGE OVER THE FORECAST AREA CONTINUES TO PUSH ENERGY NORTH OF
FORECAST AREA MID WEEK. IT MANAGES TO DELAY THE ARRIVAL OF A SECOND
SYSTEM THROUGH THUR. MODEL SOLUTIONS DIVERGE TOWARD THE END OF THE
WEEK AND HAVE LITTLE CONFIDENCE IN THEM. AT THIS TIME WILL GO WITH
CLIMATOLOGY UNTIL THERE IS SOME CONSISTENCY BETWEEN THE MODELS..
&&
.AVIATION...STRONG FRONT NOW PUSHING INTO EASTERN OREGON...WITH
MOSTLY VFR CONDITIONS. PLENTY OF SHOWERS TO PUSH INLAND THIS
MORNING...WITH OCCASIONAL MVFR. GUSTY SOUTHWEST WINDS WILL EASE
GRADUALLY BETWEEN NOW AND 18Z.
KPDX AND APPROACHES...VFR TODAY...BUT EXPECT OCCASIONAL MVFR CIGS
DOWN TO 2000 FT WITH SHOWERS...ESPECIALLY THIS MORNING. GUSTY SOUTH
TO SOUTHWEST WINDS WILL CONTINUE UNTIL 17Z...THEN GRADUALLY EASE.
WOLFE
&&
.MARINE...WORST IS OVER...BUT STILL A LOT OF GRADIENT ON BACK SIDE
OF THE LOW. WINDS STILL HITTING 40 KT...WILL MAINTAIN SOLID GALES
THROUGH EARLY AFTERNOON. SEAS TOPPING AROUND 22 TO 24 FT THIS
AM...BUT WILL EASE TO THE MID TO LOWER TEENS BY TONIGHT. NEXT SYSTEM
WILL MOVE ACROSS THE COASTAL WATERS ON MON...WITH NEAR GALE FORCE
WINDS. DIFFERENCE IS THAT THE PARENT LOW WILL PASS MUCH FURTHER TO
THE N OF THE AREA. WOLFE
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...GALE WARNING FOR THE COASTAL WATERS FROM CAPE SHOALWATER TO
FLORENCE UNTIL NOON TODAY.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS
THROUGH SUN NIGHT.
WINTERSTORM WARNING FOR THE S WA AND N AND CENTRAL OREGON
CASCADES TODAY.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KSEW 221210
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 AM PST SUN NOV 22 2009
.SYNOPSIS...A VIGOROUS FRONTAL SYSTEM IS MOVING THROUGH THE PACIFIC
NORTHWEST THIS MORNING. ITS SURFACE LOW MADE LANDFALL NEAR ASTORIA
OVERNIGHT AND IT WILL MOVE QUICKLY NORTHEAST ACROSS THE CASCADES
THIS MORNING. THE SYSTEM WILL BRING A COOL SHOWERY DAY WITH SNOW IN
THE MOUNTAINS. A WEAKER FRONT WILL MOVE THROUGH THE AREA MONDAY AND
MONDAY NIGHT...FOLLOWED BY WEAK FRONT LATE IN THE WEEK.
&&
.SHORT TERM...A VIGOROUS FRONTAL SYSTEM IS MAKING ITS THROUGH THE
PACIFIC NORTHWEST THIS MORNING...BRINGING SIGNIFICANT RAIN TO THE
LOWLANDS AND HEAVY SNOW TO THE MOUNTAINS. THE 989 MB SURFACE LOW
MADE LANDFALL NEAR ASTORIA AROUND 2 AM AND IT IS MOVING QUICKLY
EAST-NORTHEAST ACROSS THE SOUTH INTERIOR OF WESTERN WASHINGTON. THE
MAIN FRONTAL PRECIPITATION BAND BROUGHT SIGNIFICANT RAIN TO THE
LOWLANDS...AND WE RECEIVED SOME REPORTS OF WET SNOW FALLING TO NEAR
SEA LEVEL ALONG HOOD CANAL. AT 3 AM THE PRECIPITATION BAND HAD MOVED
INTO THE NORTH PART OF THE FORECAST AREA...AND LOWLAND TEMPERATURES
WERE IN THE MID 30S TO MID 40S.
THE WIND HAS BEEN THE REALLY DIFFICULT PART OF THE FORECAST WITH
THIS SYSTEM...DUE TO UNCERTAINTY WITH REGARD TO THE TRACK OF THE
SURFACE LOW. THE 06Z NAM12 MODEL LOOKS TO HAVE THE BEST HANDLE ON
THE LOW RIGHT NOW...SHOWING THAT IT WILL CONTINUE ITS EAST-NORTHEAST
TRACK AND CROSS THE CENTRAL CASCADES BEFORE 10 AM. IT LOOKS
INCREASINGLY LIKELY THAT WINDS MEETING HIGH WIND WARNING CRITERIA --
THAT IS SUSTAINED 40 MPH AND/OR GUSTS 60 MPH -- WILL NOT MATERIALIZE
...DUE PRIMARILY TO THE LOW BEING FURTHER SOUTH THAN PREVIOUSLY
ANTICIPATED. THERE WILL BE WINDY CONDITIONS MAINLY ALONG THE STRAIT
OF JUAN DE FUCA AND ADMIRALTY INLET...AND ALONG THE CENTRAL COAST
AND THROUGH THE LOWER CHEHALIS VALLEY AND SOUTHWEST INTERIOR BEHIND
THE SURFACE LOW. THE HIGH WIND WARNINGS WILL BE DROPPED WITH THE
EARLY MORNING FORECAST PACKAGE.
A WINTER STORM WARNING FOR HEAVY SNOW WILL CONTINUE FOR THE CASCADES
THROUGH 1 PM TODAY...WHILE THE WARNING FOR THE OLYMPICS IS DUE TO
EXPIRE AT 4 AM. THIS LOOKS ON TRACK. ANOTHER 8 TO 16 INCHES OF SNOW
IS LIKELY IN THE CASCADES TODAY...MOST OF IT FALLING THIS MORNING.
ANOTHER 4 TO 8 INCHES IS LIKELY IN THE OLYMPICS.
PRECIPITATION OVER THE WESTERN WASHINGTON LOWLANDS WILL BE SHOWERY
TODAY IN THE WAKE OF THE FRONT...GENERALLY TAPERING OFF DURING THE
AFTERNOON. HOWEVER A PUGET SOUND CONVERGENCE ZONE WILL LIKELY
DEVELOP AND CONTINUE THROUGH THIS EVENING.
A LESS EVENTFUL STRETCH OF WEATHER LOOKS LIKELY BEGINNING TONIGHT
AND CONTINUING THROUGH THE END OF THE WEEK. AN UPPER RIDGE WILL
PROGRESS ACROSS THE FORECAST AREA TONIGHT AND THE NEXT FRONTAL
SYSTEM UPSTREAM -- CURRENTLY OUT ALONG 150W -- WILL APPROACH THE
FORECAST AREA MONDAY. ITS WARM FRONT WILL BRING PRECIPITATION TO THE
OLYMPIC PENINSULA MONDAY MORNING...AND WIDESPREAD PRECIPITATION WILL
SPREAD INLAND LATER MONDAY AND MONDAY NIGHT AS THE COLD FRONT MOVES
THROUGH. A STRONGER RIDGE WILL MOVE OVER WESTERN WASHINGTON TUESDAY
WITH 500 MB HEIGHTS CLIMBING TO AROUND 5700 METERS. MCDONNAL
.LONG TERM...THE UPPER RIDGE MENTIONED ABOVE WILL HEAD EAST OF THE
CASCADES TUESDAY NIGHT...AND ANOTHER WARM FRONT WILL BRUSH THE
NORTHWEST CORNER OF THE AREA AS IT MOVES INTO BRITISH COLUMBIA. THE
TRAILING COLD FRONT WILL DRAG SLOWLY ACROSS THE FORECAST AREA
WEDNESDAY NIGHT THROUGH THURSDAY FOLLOWED BY ITS UPPER TROUGH
THURSDAY NIGHT AND FRIDAY. MCDONNAL
&&
.HYDROLOGY...THE ONLY CURRENT RIVER FLOOD PROBLEM IS THE SKOKOMISH
RIVER. IT IS JUST ABOVE FLOOD STAGE THIS MORNING AND WILL LIKELY
REMAIN ABOVE FLOOD STAGE INTO MONDAY. THIS IS DUE PRIMARILY TO
RELEASES OF WATER FROM CUSHMAN DAM #2. THE SYSTEM MOVING THROUGH
WESTERN WASHINGTON TODAY IS NOT A FLOOD-PRODUCING RAIN SYSTEM BUT
RATHER A HEAVY MOUNTAIN SNOW SYSTEM.
THE FRONTAL SYSTEMS EXPECTED TO ARRIVE DURING THE COMING WEEK WILL
BE ACCOMPANIED BY HIGHER SNOW LEVELS -- PROBABLY IN THE 5000 TO 7000
FT RANGE. ONE FRONT IS FORECAST TO MOVE THROUGH MONDAY AND MONDAY
NIGHT WITH ANOTHER SYSTEM MOVING SLOWLY THROUGH WEDNESDAY NIGHT
THROUGH THURSDAY NIGHT. THEY ARE NOT EXPECTED TO PRODUCE ENOUGH
PRECIPITATION TO CREATE FLOODING CONCERNS.
NO FLOODING IS EXPECTED AT ANY TIME ON THE GREEN RIVER.
&&
.AVIATION...AN UPPER LOW OVER SW WASHINGTON WILL CONTINUE MOVING E.
EXPECT AN UPPER RIDGE TO MOVE OVER THE REGION TONIGHT BEHIND THIS
SYSTEM. ELY FLOW ALOFT WILL BECOME NLY THIS AFTERNOON...AND THEN WLY
OVERNIGHT.
THE STRONG...SFC LOW THAT DEVELOPED OFF THE FAR NORTHERN OREGON
COAST MOVED INLAND...OVER THE MOUTH OF THE COLUMBIA RIVER...ABOUT
10Z. THIS LOW NOW APPEARED TO BE NEAR KKLS AND WAS CONTINUING TO
MOVE E. EXPECT STRONG ONSHORE FLOW TO DEVELOP BY LATE THIS MORNING
IN THE WAKE OF THIS FEATURE. THE STRONGEST WINDS WILL LIKELY OCCUR
OVER THE COAST AND ADMIRALTY INLET AREA. EXPECT THE FLOW TO WEAKEN
OVERNIGHT.
A PUGET SOUND CONVERGENCE ZONE /PSCZ/ WILL DEVELOP N OF THE
SNOHOMISH/KING COUNTY BORDER LATER THIS MORNING AND THEN MOVE S
DURING THE AFTERNOON...BECOMING QUASISTATIONARY OVER THE N CENTRAL
PUGET SOUND. AT THIS TIME...IT LOOKS LIKE THE PSCZ WILL REMAIN N OF
KBFI. WINDS WILL BACK TONIGHT AS THE PRES GRADIENT BECOMES SLY...
THUS EXPECT THE PSCZ TO DRIFT BACK TO THE N AND THEN DISSIPATE LATER
TONIGHT.
CIGS WILL GENERALLY BE IN THE 4-7K FT RANGE TODAY. EXPECT THE LOWER
CLOUD DECK TO BECOME SCATTERED THIS EVENING BUT THERE WILL BE AN
INCREASE IN HIGH LEVEL MOISTURE...ABOVE 15K FT...OVERNIGHT. EXPECT
LOCALIZED FOG...REDUCING VSBYS INTO 3-5SM...TO DEVELOP LATER
TONIGHT...BUT MAINLY IN THE FAVORED RIVER VALLEYS.
KSEA...ELY WINDS WILL DROP OFF BY MIDMORNING AND THEN KICK UP FROM
THE SW LATER THIS MORNING. CIGS WILL MAINLY BE IN THE 5-6K FT
RANGE...ALTHOUGH THE CLOUDS WILL BECOME SCATTERED LATER TODAY...IF
NOT EARLIER.
&&
.MARINE...STRONG WESTERLY FLOW WILL DEVELOP IN THE WAKE OF A 985 MB
LOW THAT MOVED INLAND EARLIER. THIS WILL RESULT IN GALE FORCE
WESTERLY WINDS OVER MUCH OF THE AREA...WITH A BRIEF PERIOD OF STORM
FORCE WINDS POSSIBLE OVER THE CENTRAL STRAIT OF JUAN DE FUCA THIS
MORNING. THE ONSHORE FLOW WILL WEAKEN TONIGHT. ANOTHER...BUT
WEAKER...FRONTAL SYSTEM WILL AFFECT THE AREA ON MON. EXPECT OFFSHORE
FLOW TO DEVELOP ON TUE.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...A FLOOD WARNING REMAINS IN EFFECT FOR THE SKOKOMISH RIVER IN
MASON COUNTY.
A WINTER STORM WARNING REMAINS EFFECT FOR THE CASCADES TIL
1 PM TODAY.
A WIND ADVISORY IS IN EFFECT FOR THE ADMIRALTY INLET AREA...
SOUTHWEST INTERIOR...LOWER CHEHALIS VALLEY...AND STRAIT OF JUAN
DE FUCA.
PZ...GALE WARNINGS ARE IN EFFECT FOR ALL WATERS TIL 4 PM TODAY.
A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR ROUGH GRAYS
HARBOR BAR CONDITIONS TIL 4 PM MON.
$$
WWW.WEATHER.GOV/SEATTLE
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.
000
FXUS66 KOTX 221159
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
354 AM PST SUN NOV 22 2009
.SYNOPSIS...
A STRONG AND COLD STORM SYSTEM WILL BRING MODERATE TO HEAVY
SNOWFALL OVER MUCH OF THE REGION TODAY. A BRIEF BREAK TONIGHT AND
MONDAY WILL GIVE WAY TO A WEAKER STORM SYSTEM MONDAY NIGHT. THE
THANKSGIVING HOLIDAY WILL LIKELY BE DRY...WITH DETERIORATING
CONDITIONS TOWARD THE END OF THE WORK WEEK.
&&
.DISCUSSION...
TODAY...INCOMING STORM SYSTEM IS STILL ON TRACK FOR A MORNING
WALLOPING ACROSS MOST OF THE REGION. SATELLITE AND RADAR CLEARLY
INDICATE A STRONG AND DYNAMIC NEGATIVELY TILTED TROUGH DRIVING
INTO THE COAST THIS MORNING...WITH THE LOW CENTER NEAR HOQUIAM AND
ASTORIA AT 2AM THIS MORNING. LATEST MODELS HAVE SETTLED IN REASONABLE
AGREEMENT WITH THE TRACK OF THIS LOW...EJECTING INLAND AND
WEAKENING SLIGHTLY AS IT MOVES NORTHEAST THROUGH THE NORTHERN
REACHES OF THE FORECAST AREA TODAY. A FRONTAL COMPLEX APPARENTLY
CONSISTING OF A WARM FRONT FOLLOWED BY A STRONG COLD OCCLUDED
FRONT WILL PRODUCE 3 TO 5 HOURS OF MODERATE AND OCCASIONALLY HEAVY
PRECIPITATION AS IT PUSHES THROUGH. CURRENT OBSERVATIONS SUGGEST
TEMPERATURE/DEW POINT SPREADS ARE SUFFICIENT TO ALLOW WET BULB
COOLING WELL INTO THE ACCUMULATING SNOW ZONE AT REGIONAL
OBSERVATION SITES ABOVE 2000 FEET ELEVATION WHEN THE FRONTAL
PRECIPITATION GETS UNDERWAY. SO...FOR THIS MORNING THE MAIN STORY
IS THE SNOW POTENTIAL. CURRENT HIGHLIGHTS LOOK PLAUSIBLE AND
WILL NOT BE CHANGED. OVER THE WESTERN ZONES AND CASCADES A 3 TO 5
HOUR PERIOD OF MODERATE SNOW AND LOWER VALLEY WET SNOW OR RAIN MIX
WILL OCCUR THIS MORNING BEFORE ABRUPTLY TAPERING OFF TO SHOWERS BY
MID-MORNING AS STRONG WESTERLY FLOW BEHIND THE LOW CENTER ALLOWS A
RAIN SHADOW EFFECT. OVER THE EASTERN ZONES RELATIVELY BENIGN
CONDITIONS WILL SHARPLY DETERIORATE INTO A PERIOD OF MODERATE AND
OCCASIONALLY HEAVY SNOW STARTING JUST BEFORE DAWN AND LASTING
UNTIL 9 OR 10 AM BEFORE TAPERING OFF TO SHOWERS. ASSUMING A
PROBABLE 1/2 TO 1 INCH PER HOUR OF SNOW ACCUMULATION FOR A FEW
HOURS AT AND IMMEDIATELY BEHIND THE FRONT...CURRENT FORECAST OF
WIDESPREAD 2 TO 4 INCHES ABOVE 2000 FEET IN EASTERN WASHINGTON AND
A COUPLE MORE INCHES IN IDAHO STILL LOOKS INDUBITABLY
PLAUSIBLE...WITH HIGHER AMOUNTS IN THE MOUNTAINS. THIS AFTERNOON
POST FRONTAL WINDS WILL KICK IN MAKING FOR A WINDY AND GUSTY
AFTERNOON AT ALL LOCATIONS. AT THIS TIME IT APPEARS THE
GRADIENT...WHILE TIGHTENING DRAMATICALLY WILL NOT BE SUFFICIENT
FOR SUSTAINED WIND ADVISORY CRITERIA...AND GUST POTENTIAL WILL
PROBABLY BE IN THE 30 TO 40 MPH RANGE ON EXPOSED TERRAIN THIS
AFTERNOON...AGAIN NOT QUITE WIND ADVISORY CRITERIA BUT CLOSE.
TODAYS HIGH TEMPERATURES SHOULD RECOVER TO WELL ABOVE FREEZING
LATE TODAY AS A STRONGLY MIXED AIR MASS ALLOWS ADIABATIC
COMPRESSIONAL WARMING INTO THE UPPER 30S TO LOW 40S AT MANY LOWER
ELEVATION LOCATIONS.
TONIGHT A GENERAL IMPROVEMENT IN CONDITIONS EXPECTED AS THE
OFFENDING WEATHER SYSTEM BOLTS INTO MONTANA AND ALBERTA. EXCEPT
FOR LINGERING MOUNTAIN OROGRAPHIC SNOW SHOWERS...MAINLY DRY
CONDITIONS IN THE BASIN ARE EXPECTED WITH AN ISOLATED ROGUE LIGHT
SNOW SHOWER OR TWO OVER THE RISING TERRAIN OF THE EASTERN BASIN. A
SHARP SHORT WAVE RIDGE WILL BUILD OVER THE REGION WITH DECREASING
WINDS AS A SURFACE HIGH PRESSURE BECOMES ESTABLISHED OVER IDAHO.
FOR MONDAY THE SHORT WAVE RIDGE WILL BEGIN TO BE CRESTED BY
INCREASING MOISTURE FROM THE NEXT SYSTEM. INCREASING AND
THICKENING MID AND HIGH LEVEL CLOUDS WILL CHARACTERIZE THE SKY
COVER...WITH AN INCREASING POSSIBILITY OF LIGHT SNOW ONCE AGAIN
BEGINNING OVER THE WESTERN ZONES BY LATE AFTERNOON. /FUGAZZI
FOR MONDAY NIGHT AND TUESDAY...A WEAK STORM WILL RIPPLE ACROSS THE
NORTHERN TIER ZONES. CURRENTLY...THIS MOISTURE PLUME IS SEEN
CROSSING 50/160W AND HEADING OVER THE SHORTWAVE RIDGE IN THE GULF
OF ALASKA. THE MODELS WEAKEN THE LOW CENTER AND PULL IT NORTH
ACROSS THE YUKON...AND THEN DRAG THE REMAINS OF THE FRONTAL
BOUNDARY ACROSS THE WASHINGTON CASCADES BEFORE FALLING APART
ACROSS THE NORTHEAST WASHINGTON. HIGH PRESSURE BUILDS IN QUICKLY
BEHIND THIS FEATURE...LEANING TOWARD A LIGHT PRECIPITATION EVENT
ESPECIALLY FOR AREAS NORTH OF HIGHWAY 2. ALTHOUGH TEMPERATURES WILL
DROP TO NEAR FREEZING WITH MAINLY SNOW IN THE HIGHER VALLEYS AND
MOUNTAINS...COOLING BEHIND THE FRONT WILL BE MINIMAL AND TEMPERATURES
WILL GRADUALLY WARM ON TUESDAY.
THEN TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...THE UPPER LEVEL RIDGE
BUILDS...BRINGING WARMER AND SOMEWHAT DRIER AIR IN FROM THE SOUTH.
YET WITH THE TOP OF RIDGE IN CLOSE PROXIMITY TO THE CANADIAN
BORDER...ANTICIPATE A DIRTY RIDGE SCENARIO AND MID AND HIGH LEVEL
MOISTURE SPREADING ACROSS MUCH OF THE FORECAST AREA. IN
ADDITION...WEAK ISENTROPIC LIFT WILL LEAD TO LIGHT SHOWERS OVER
THE NORTHERN MOUNTAINS THROUGH MID WEEK. THE RIDGE IS EXPECTED TO
AMPLIFY WHICH WILL PUSH MOST OF THE MOISTURE NORTH OF THE REGION
BY WEDNESDAY.
FOR THANKSGIVING INTO FRIDAY...MADE SOME CHANGES TO THE HOLIDAY
FORECAST. LATEST MODEL RUN WITH THE GFS AND ECWMF KEEP THE UPPER LEVEL
RIDGE STRONG OVER THE INLAND NORTHWEST AND SLOW DOWN THE NEXT
STORM SYSTEM. SO OPTED TO DRY OUT MUCH OF THE REGION ON
THANKSGIVING DAY...AND THEN SHOW A GRADUAL BREAK DOWN OF THE
RIDGE THURSDAY NIGHT INTO FRIDAY WITH A SLOW MOVING COLD FRONT.
EMPHASIZED THE BEST CHANCE OF PRECIPITATION FOR NORTHEAST
WASHINGTON AND NORTH IDAHO FOR FRIDAY WHEN THE OROGRAPHIC AND THE
SYNOPTIC LIFT COMBINE.
THE WEEKEND...COOLER AND UNSETTLED WEATHER IS FORECAST AS AN
UPPER LEVEL TROUGH MOVING THROUGH THE REGION...FOLLOWED BY AN
UNSTABLE NORTHWEST TO NORTH FLOW OVER THE INLAND NORTHWEST. WILL
LEAN TOWARD POTENTIAL FOR MAINLY MOUNTAIN SHOWERS. /RFOX.
&&
.AVIATION...
A STRONG AND COLD LOW PRESSURE SYSTEM WILL PASS THROUGH THE FORECAST
AREA TODAY. A STRONG COLD FRONT WILL PASS THROUGH KEAT AT 15Z AND
KGEG BY 18Z. AHEAD OF THIS FRONT WIDESPREAD IFR CONDITIONS WITH
OCCASIONAL LIFR CONDITIONS IN SNOW ARE EXPECTED AT ALL TAF SITES
EXCEPT KLWS. AFTER THE FRONTAL PASSAGE AT KEAT AND KMWH MAINLY VFR
CONDITIONS ARE EXPECTED...BUT WITH INCREASING WESTERLY WINDS GUSTING
TO 30KTS THIS AFTERNOON. EAST OF A LINE FROM KOMK TO KLWS LINGERING
POST FRONTAL SCATTERED SNOW SHOWERS WILL PROMOTE OCCASIONAL MVFR AND
POSSIBLY BRIEF IFR VISIBILITIES AND CEILINGS IN SNOW SHOWERS...WITH
WINDY AND GUSTY CONDITIONS THROUGH THE AFTERNOON. AFTER 00Z SNOW
SHOWERS WILL TAPER OFF...BUT UPSLOPE STRATUS FIELDS MAY CREATE MVFR
AND IFR CEILINGS AT THE KGEG AREA TAF SITES THROUGH 12Z MONDAY.
MOUNTAINS SURROUNDING THE COLUMBIA BASIN WILL REMAIN HEAVILY
OBSCURED IN COUDS AND PCPN TODAT THROUGH 12Z MONDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 41 27 37 30 40 31 / 100 10 20 50 20 10
COEUR D`ALENE 37 29 36 30 41 33 / 100 20 20 60 20 10
PULLMAN 39 29 39 30 43 33 / 100 20 10 40 30 0
LEWISTON 47 34 45 32 49 35 / 80 10 10 20 20 0
COLVILLE 38 31 37 29 41 34 / 100 10 50 70 20 20
SANDPOINT 37 30 35 28 38 31 / 100 20 50 70 30 20
KELLOGG 37 29 32 29 40 32 / 100 70 20 60 30 10
MOSES LAKE 46 23 42 27 45 30 / 70 0 20 30 10 0
WENATCHEE 46 29 42 30 45 33 / 90 10 30 40 10 0
OMAK 45 23 38 27 43 30 / 100 0 70 80 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WINTER WEATHER ADVISORY UNTIL 10 PM PST THIS EVENING FOR
NORTHERN PANHANDLE.
WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR IDAHO
PALOUSE.
WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR COEUR
D`ALENE AREA.
WINTER STORM WARNING UNTIL 1 AM PST MONDAY FOR CENTRAL PANHANDLE
MOUNTAINS.
WA...WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
NORTHEAST MOUNTAINS...SPOKANE AREA.
WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR EAST
SLOPES NORTHERN CASCADES.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR OKANOGAN
HIGHLANDS...OKANOGAN VALLEY.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR UPPER COLUMBIA
BASIN...WATERVILLE PLATEAU.
WINTER WEATHER ADVISORY UNTIL 10 PM PST THIS EVENING FOR
NORTHEAST BLUE MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
WASHINGTON PALOUSE.
&&
$$
000
FXUS66 KOTX 221039
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
239 AM PST SUN NOV 22 2009
.SYNOPSIS...
A STRONG AND COLD STORM SYSTEM WILL BRING MODERATE TO HEAVY
SNOWFALL OVER MUCH OF THE REGION TODAY. A BRIEF BREAK TONIGHT AND
MONDAY WILL GIVE WAY TO A WEAKER STORM SYSTEM MONDAY NIGHT. THE
THANKSGIVING HOLIDAY WILL LIKELY BE DRY...WITH DETERIORATING
CONDITIONS TOWARD THE END OF THE WORK WEEK.
&&
.DISCUSSION...
TODAY...INCOMING STORM SYSTEM IS STILL ON TRACK FOR A MORNING
WALLOPING ACROSS MOST OF THE REGION. SATELLITE AND RADAR CLEARLY
INDICATE A STRONG AND DYNAMIC NEGATIVELY TILTED TROUGH DRIVING
INTO THE COAST THIS MORNING...WITH THE LOW CENTER NEAR HOQUIAM AND
ASTORIA AT 2AM THIS MORNING. LATEST MODELS HAVE SETTLED IN REASONABLE
AGREEMENT WITH THE TRACK OF THIS LOW...EJECTING INLAND AND
WEAKENING SLIGHTLY AS IT MOVES NORTHEAST THROUGH THE NORTHERN
REACHES OF THE FORECAST AREA TODAY. A FRONTAL COMPLEX APPARENTLY
CONSISTING OF A WARM FRONT FOLLOWED BY A STRONG COLD OCCLUDED
FRONT WILL PRODUCE 3 TO 5 HOURS OF MODERATE AND OCCASIONALLY HEAVY
PRECIPITATION AS IT PUSHES THROUGH. CURRENT OBSERVATIONS SUGGEST
TEMPERATURE/DEW POINT SPREADS ARE SUFFICIENT TO ALLOW WET BULB
COOLING WELL INTO THE ACCUMULATING SNOW ZONE AT REGIONAL
OBSERVATION SITES ABOVE 2000 FEET ELEVATION WHEN THE FRONTAL
PRECIPITATION GETS UNDERWAY. SO...FOR THIS MORNING THE MAIN STORY
IS THE SNOW POTENTIAL. CURRENT HIGHLIGHTS LOOK PLAUSIBLE AND
WILL NOT BE CHANGED. OVER THE WESTERN ZONES AND CASCADES A 3 TO 5
HOUR PERIOD OF MODERATE SNOW AND LOWER VALLEY WET SNOW OR RAIN MIX
WILL OCCUR THIS MORNING BEFORE ABRUPTLY TAPERING OFF TO SHOWERS BY
MID-MORNING AS STRONG WESTERLY FLOW BEHIND THE LOW CENTER ALLOWS A
RAIN SHADOW EFFECT. OVER THE EASTERN ZONES RELATIVELY BENIGN
CONDITIONS WILL SHARPLY DETERIORATE INTO A PERIOD OF MODERATE AND
OCCASIONALLY HEAVY SNOW STARTING JUST BEFORE DAWN AND LASTING
UNTIL 9 OR 10 AM BEFORE TAPERING OFF TO SHOWERS. ASSUMING A
PROBABLE 1/2 TO 1 INCH PER HOUR OF SNOW ACCUMULATION FOR A FEW
HOURS AT AND IMMEDIATELY BEHIND THE FRONT...CURRENT FORECAST OF
WIDESPREAD 2 TO 4 INCHES ABOVE 2000 FEET IN EASTERN WASHINGTON AND
A COUPLE MORE INCHES IN IDAHO STILL LOOKS INDUBITABLY
PLAUSIBLE...WITH HIGHER AMOUNTS IN THE MOUNTAINS. THIS AFTERNOON
POST FRONTAL WINDS WILL KICK IN MAKING FOR A WINDY AND GUSTY
AFTERNOON AT ALL LOCATIONS. AT THIS TIME IT APPEARS THE
GRADIENT...WHILE TIGHTENING DRAMATICALLY WILL NOT BE SUFFICIENT
FOR SUSTAINED WIND ADVISORY CRITERIA...AND GUST POTENTIAL WILL
PROBABLY BE IN THE 30 TO 40 MPH RANGE ON EXPOSED TERRAIN THIS
AFTERNOON...AGAIN NOT QUITE WIND ADVISORY CRITERIA BUT CLOSE.
TODAYS HIGH TEMPERATURES SHOULD RECOVER TO WELL ABOVE FREEZING
LATE TODAY AS A STRONGLY MIXED AIR MASS ALLOWS ADIABATIC
COMPRESSIONAL WARMING INTO THE UPPER 30S TO LOW 40S AT MANY LOWER
ELEVATION LOCATIONS.
TONIGHT A GENERAL IMPROVEMENT IN CONDITIONS EXPECTED AS THE
OFFENDING WEATHER SYSTEM BOLTS INTO MONTANA AND ALBERTA. EXCEPT
FOR LINGERING MOUNTAIN OROGRAPHIC SNOW SHOWERS...MAINLY DRY
CONDITIONS IN THE BASIN ARE EXPECTED WITH AN ISOLATED ROGUE LIGHT
SNOW SHOWER OR TWO OVER THE RISING TERRAIN OF THE EASTERN BASIN. A
SHARP SHORT WAVE RIDGE WILL BUILD OVER THE REGION WITH DECREASING
WINDS AS A SURFACE HIGH PRESSURE BECOMES ESTABLISHED OVER IDAHO.
FOR MONDAY THE SHORT WAVE RIDGE WILL BEGIN TO BE CRESTED BY
INCREASING MOISTURE FROM THE NEXT SYSTEM. INCREASING AND
THICKENING MID AND HIGH LEVEL CLOUDS WILL CHARACTERIZE THE SKY
COVER...WITH AN INCREASING POSSIBILITY OF LIGHT SNOW ONCE AGAIN
BEGINNING OVER THE WESTERN ZONES BY LATE AFTERNOON. /FUGAZZI
FOR MONDAY NIGHT AND TUESDAY...A WEAK STORM WILL RIPPLE ACROSS THE
NORTHERN TIER ZONES. CURRENTLY...THIS MOISTURE PLUME IS SEEN
CROSSING 50/160W AND HEADING OVER THE SHORTWAVE RIDGE IN THE GULF
OF ALASKA. THE MODELS WEAKEN THE LOW CENTER AND PULL IT NORTH
ACROSS THE YUKON...AND THEN DRAG THE REMAINS OF THE FRONTAL
BOUNDARY ACROSS THE WASHINGTON CASCADES BEFORE FALLING APART
ACROSS THE NORTHEAST WASHINGTON. HIGH PRESSURE BUILDS IN QUICKLY
BEHIND THIS FEATURE...LEANING TOWARD A LIGHT PRECIPITATION EVENT
ESPECIALLY FOR AREAS NORTH OF HIGHWAY 2. ALTHOUGH TEMPERATURES WILL
DROP TO NEAR FREEZING WITH MAINLY SNOW IN THE HIGHER VALLEYS AND
MOUNTAINS...COOLING BEHIND THE FRONT WILL BE MINIMAL AND TEMPERATURES
WILL GRADUALLY WARM ON TUESDAY.
THEN TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...THE UPPER LEVEL RIDGE
BUILDS...BRINGING WARMER AND SOMEWHAT DRIER AIR IN FROM THE SOUTH.
YET WITH THE TOP OF RIDGE IN CLOSE PROXIMITY TO THE CANADIAN
BORDER...ANTICIPATE A DIRTY RIDGE SCENARIO AND MID AND HIGH LEVEL
MOISTURE SPREADING ACROSS MUCH OF THE FORECAST AREA. IN
ADDITION...WEAK ISENTROPIC LIFT WILL LEAD TO LIGHT SHOWERS OVER
THE NORTHERN MOUNTAINS THROUGH MID WEEK. THE RIDGE IS EXPECTED TO
AMPLIFY WHICH WILL PUSH MOST OF THE MOISTURE NORTH OF THE REGION
BY WEDNESDAY.
FOR THANKSGIVING INTO FRIDAY...MADE SOME CHANGES TO THE HOLIDAY
FORECAST. LATEST MODEL RUN WITH THE GFS AND ECWMF KEEP THE UPPER LEVEL
RIDGE STRONG OVER THE INLAND NORTHWEST AND SLOW DOWN THE NEXT
STORM SYSTEM. SO OPTED TO DRY OUT MUCH OF THE REGION ON
THANKSGIVING DAY...AND THEN SHOW A GRADUAL BREAK DOWN OF THE
RIDGE THURSDAY NIGHT INTO FRIDAY WITH A SLOW MOVING COLD FRONT.
EMPHASIZED THE BEST CHANCE OF PRECIPITATION FOR NORTHEAST
WASHINGTON AND NORTH IDAHO FOR FRIDAY WHEN THE OROGRAPHIC AND THE
SYNOPTIC LIFT COMBINE.
THE WEEKEND...COOLER AND UNSETTLED WEATHER IS FORECAST AS AN
UPPER LEVEL TROUGH MOVING THROUGH THE REGION...FOLLOWED BY AN
UNSTABLE NORTHWEST TO NORTH FLOW OVER THE INLAND NORTHWEST. WILL
LEAN TOWARD POTENTIAL FOR MAINLY MOUNTAIN SHOWERS. /RFOX.
&&
.AVIATION...
CONDITIONS WILL RAPIDLY DETERIORATE AT THE TAF SITES AS A STRONG
SYSTEM MOVES THROUGH THE AREA. VISIBILITIES AND CEILINGS WILL CRASH
FROM WEST TO EAST WITH A BURST OF MAINLY SN AND +SN MOVING THROUGH
THE AREA. TIMING OF WORST CONDITIONS WILL BE BTWN 09Z-19Z AT THE
TAF SITES WITH THE EARLIER ONSET FOR LOCATIONS NEAR THE CASCADES
AND A LATER ONSET OVER N IDAHO. BLSN IS ALSO EXPECTED AT KPUW BTWN
12-18Z. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 41 27 37 30 40 31 / 100 10 20 50 20 10
COEUR D`ALENE 37 29 36 30 41 33 / 100 20 20 60 20 10
PULLMAN 39 29 39 30 43 33 / 100 20 10 40 30 0
LEWISTON 47 34 45 32 49 35 / 80 10 10 20 20 0
COLVILLE 38 31 37 29 41 34 / 100 10 50 70 20 20
SANDPOINT 37 30 35 28 38 31 / 100 20 50 70 30 20
KELLOGG 37 29 32 29 40 32 / 100 70 20 60 30 10
MOSES LAKE 46 23 42 27 45 30 / 70 0 20 30 10 0
WENATCHEE 46 29 42 30 45 33 / 90 10 30 40 10 0
OMAK 45 23 38 27 43 30 / 100 0 70 80 10 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WINTER WEATHER ADVISORY UNTIL 10 PM PST THIS EVENING FOR
NORTHERN PANHANDLE.
WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR IDAHO
PALOUSE.
WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR COEUR
D`ALENE AREA.
WINTER STORM WARNING UNTIL 1 AM PST MONDAY FOR CENTRAL PANHANDLE
MOUNTAINS.
WA...WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
NORTHEAST MOUNTAINS...SPOKANE AREA.
WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR EAST
SLOPES NORTHERN CASCADES.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR OKANOGAN
HIGHLANDS...OKANOGAN VALLEY.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR UPPER COLUMBIA
BASIN...WATERVILLE PLATEAU.
WINTER WEATHER ADVISORY UNTIL 10 PM PST THIS EVENING FOR
NORTHEAST BLUE MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
WASHINGTON PALOUSE.
&&
$$
000
FXUS66 KPQR 221030
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
230 AM PST SUN NOV 22 2009
.SYNOPSIS...A STRONG SURFACE LOW OVER SW WA THIS MORNING WILL
CONTINUE TO MOVE E TODAY AND WEAKEN. HIGH PRES WILL BUILD IN OVER
WESTERN OREGON LATER TODAY AND TONIGHT. A WARM FRONT OFF THE COAST
ON MON WILL LIFT NE TOWARDS NW OREGON AND WESTERN WA....THEN STALL
ON TUE. WED THE FRONT WILL FINALLY LIFT N INTO WA...BEFORE A COLD
FRONT PUSHES SE THROUGH THE REGION THU.
&&
.SHORT TERM...SURFACE LOW PASSED JUST N OF BUOY 46089 A FEW HOURS
AGO...APPARENTLY MOVING ENE HEADED TOWARDS ROUGHLY WILLAPA BAY. COLD
FRONT HAS PUSHED E INTO THE CENTRAL OREGON COAST WITH PEAK GUSTS
AROUND 80 MPH. BUOYS INDICATE AN IMPRESSIVE WIND FIELD IN THE POST
FRONTAL WESTERLY FLOW...WITH STORM FORCE GUSTS CONTINUING THROUGH
09Z AT 46089 AND 46050. BASED ON E WINDS ALONG THE N OREGON
COAST...FRONT APPEARS TO BE OCCLUDED N OF KTMK...SO ANY HIGH WINDS N
OF THERE WILL NEED TO COME OUT OF THE SW BEHIND THE FRONT. STRONG
PRESSURE RISES BEHIND THE COLD FRONT HAVE MAINTAINED HIGH WINDS FOR
A COUPLE HOURS BEHIND THE FRONT. WITH THE STRONG PRESSURE RISES
BEHIND THE FRONT...WILL LIKELY NEED TO HANG ONTO THE INLAND WIND
ADVISORY EARLY THIS MORNING. ELSEWHERE EXPECT BE ABLE TO DROP THE
HIGH WIND WARNINGS WITH THE NEXT FORECAST PACKAGE.
SNOW INTENSITY PICKED UP IN THE CASCADES AFTER ROUGHLY 10 PM AS
HEAVIER BANDS OF PRECIPITATION LIFTED UP. SATELLITE AND RADAR
SUGGEST AT LEAST ONE MORE BAND OF ENHANCED PRECIPITATION YET EARLY
THIS MORNING...BEFORE THE STRONG OROGRAPHIC WESTERLY FLOW KICKS IN
BEHIND THE FRONT. OROGRAPHICS WEAKEN IN THE AFTERNOON AS H8 FLOW
WEAKENS...SO WE SHOULD SEE SNOW ACCUMULATIONS DROP OFF CONSIDERABLY
IN THE AFTERNOON.
POST FRONTAL SHOWERS DROP OFF QUICKLY TONIGHT...LAST ON THE N PART
OF THE CASCADES. AN AREA OF WARM AIR ADVECTION SETS UP OVER THE NW
PART OF THE FORECAST AREA MON...AND CONTINUES INTO TUE. A WEAK
SHORTWAVE MOVES ACROSS THE TOP OF THE DEVELOPING UPPER RIDGE
TUE...BRINGING THE BEST CHANCE FOR OVERRUNNING PRECIPITATION TO THE
NW PART OF THE AREA ON TUE.
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
WEAK HIGH PRES RIDGE OVER THE FORECAST AREA CONTINUES TO PUSH ENERGY
NORTH OF FORECAST AREA MID WEEK. IT MANAGES TO DELAY THE ARRIVAL OF
A SECOND SYSTEM THROUGH THUR. MODEL SOLUTIONS DIVERGE TOWARD THE END
OF THE WEEK AND HAVE LITTLE CONFIDENCE IN THEM. AT THIS TIME WILL GO
WITH CLIMATOLOGY UNTIL THERE IS SOME CONSISTENCY BETWEEN THE MODELS..
&&
.AVIATION...STRONG FRONT NOW PUSHING ACROSS THE REGION...WITH MOSTLY
VFR CONDITIONS. PLENTY OF SHOWERS TO PUSH INLAND THIS MORNING...WITH
OCCASIONAL MVFR. MAIN STORY IS THE GUSTY SOUTH TO SOUTHWEST WINDS
OVER REGION. WINDS WILL EASE GRADUALLY BETWEEN 14Z AND 18Z.
KPDX AND APPROACHES...VFR TODAY...BUT EXPECT OCCASIONAL MVFR CIGS
DOWN TO 2000 FT WITH SHOWERS...ESPECIALLY AFTER 14Z. GUSTY SOUTH TO
SOUTHWEST WINDS WILL CONTINUE UNTIL 17Z...THEN GRADUALLY EASE.
&&
.MARINE...WORST IS OVER...BUT STILL A LOT OF GRADIENT ON BACK SIDE
OF THE LOW. WITH WINDS STILL HITTING 45 TO 50 KT...WILL MAINTAIN
STORM WARNING UNTIL 7 AM. THEN SOLID GALES AFTERWARDS. SEAS TOPPING
AROUND 22 TO 24 FT THIS AM...BUT LIKE THE WIND THESE TOO SHALL EASE
TODAY. NEXT SYSTEM WILL MOVE ACROSS THE COASTAL WATERS ON MON...WITH
NEAR GALE FORCE WIND. DIFFERENCE IS THAT THE PARENT LOW WILL PASS
MUCH FURTHER TO THE N OF THE AREA. &&
.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...STORM WARNING FOR THE COASTAL WATERS FROM CAPE SHOALWATER TO
FLORENCE UNTIL 7 AM THIS MORNING.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS
THROUGH SUN NIGHT.
WINTER STORM WARNING FOR THE S WA AND N AND CENTRAL OREGON
CASCADES TODAY.
WIND ADVISORY FOR THE WILLAMETTE VALLEY...THE LOWER
COLUMBIA...AND THE I-5 CORRIDOR FOR THIS EVENING THROUGH
7 AM.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KOTX 220615
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1015 PM PST SAT NOV 21 2009
.SYNOPSIS...
A STRONGER AND COLDER STORM SYSTEM WILL BRING MODERATE TO HEAVY
SNOWFALL OVER MUCH OF THE REGION TONIGHT AND SUNDAY. A SERIES OF
STORM SYSTEMS WILL CONTINUE TO PASS THROUGH THE INLAND NORTHWEST
EVERY 24 TO 36 HOURS THROUGH AT LEAST THE MIDDLE OF NEXT WEEK.
&&
.DISCUSSION...
...MODERATE TO HEAVY SNOWFALL OVER MOST OF THE AREA TONIGHT AND SUNDAY...
WATER VAPOR SATELLITE SHOWS A STRENGTHING LOW APPROACHING THE
SOUTHERN WASHINGTON AND NORTHERN OREGON COAST. SFC ANALYSIS AT 05Z
SHOWED THE SFC LOW TO BE LOCATED BETWEEN HOQUIAM AND ASTORIA JUST
OFF THE COAST WITH SFC PRESSURE FALLING BY THE HOUR...WITH A
CENTRAL PRESSURE ESTIMATED TO BE NEAR 991MB. THIS FITS WELL WITH
THE GFS ALTHOUGH MAY BE SLIGHTLY FURTHER SOUTH. THERE IS GOOD
AGREEMENT BETWEEN THE GFS AND NAM IN DUMBBELLING THIS LOW NORTHEAST
TONIGHT AROUND ANOTHER SFC LOW NEAR THE QUEEN CHARLOTTE ISLANDS.
SATELLITE TRENDS IN THE LAST HOUR INDICATE THE TURNING TOWARDS THE
NORTHEAST IS JUST BEGINNING SO THE GFS IDEA MATCHES WELL WITH THE
SATELLITE. THE LOW WILL WEAKEN AS IT CROSSES THE CASCADES BUT IT
WILL SEND A COLD OCCLUSION OVER THE AREA BRINGING A BURST OF HEAVY
PRECIPITATION FOR 3-6 HRS WITH PRECIPITATION PERSISTING OVER NORTH
IDAHO FOR A LONGER PERIOD DUE TO STRONG LOW LEVEL UPSLOPE FLOW.
TIMING OF THE HEAVY PRECIP BAND LOOKS TO CROSS THE CASCADES
AROUND MIDNIGHT...TRACKING INTO THE OKANOGAN VALLEY AND COLUMBIA
BASIN OVERNIGHT INTO EARLY SUNDAY MORNING...AND THEN ACROSS
EASTERN WASHINGTON IN THE EARLY TO MID MORNING HOURS ON
SUNDAY...AND THEN FINALLY INTO N IDAHO MID TO LATE MORNING. THE
GFS AND NAM BRING ABOUT A QUARTER INCH OF LIQUID PRECIP WITH THIS
COLD OCCLUSION. SNOW LEVELS WILL BE TRICKY TONIGHT INTO SUNDAY
MORNING. AS OF 10 PM LIGHT RAIN WAS FALLING IN OMAK...WITH PRECIP
TYPE OF RAIN ALSO SUPPORTED IN WENATCHEE. HOWEVER WITH THE HEAVIER
PRECIP RATES EXPECTED...MODELS QUICKLY COOL THE LOWER PART OF THE
ATMOSPHERE WITH 1000-850MB THICKNESSES FALLING TO 1300-1305DM
WHICH IS LOW ENOUGH FOR SNOW FOR MOST LOCATIONS. THUS RAIN AT OMAK
SHOULD CHANGE OVER TO SNOW OVERNIGHT SO ADVISORY WAS UPDATED TO
INCLUDE THE LOWER PART OF THE VALLEY. WENATCHEE CURRENTLY IT A
LITTLE WARMER SO SUB ADVISORY ACCUMULATIONS ARE MORE LIKELY MAINLY
ON GRASSY SURFACES. THE ONE AREA WHERE A RAIN AND SNOW MIX IS
MORE PROBABLE IS ELEVATIONS BELOW 2000 FEET SOUTH OF A LINE FROM
MOSES LAKE TO LEWISTON AS SLIGHTLY WARMER LOW LEVEL AIR RESIDES.
AS THE PRECIP SWINGS INTO NE WA/N IDAHO SUNDAY MORNING...ALL AREAS
SHOULD SEE A BURST OF HEAVY SNOW AS CURRENT WET BULB ZERO
TEMPERATURES ARE 32F OR BELOW. WITH THE BRIEF PERIOD OF HEAVY SNOW
EXPECTED MOST LOCATIONS ARE UNDER A WINTER WEATHER ADVISORY.
HOWEVER UPSLOPE FLOW WILL KEEP SNOW PERSISTING FOR THE IDAHO
PALOUSE...COEUR D`ALENE AREA...AND CENTRAL PANHANDLE MOUNTAINS ON
SUNDAY SO WINTER STORM WARNINGS ARE IN EFFECT. PRESSURE GRADIENTS
ALSO TIGHTEN SUNDAY MORNING WITH WINDY CONDITIONS DEVELOPING ON
THE PALOUSE...IN THE BLUE MTNS...AND CENTRAL PANHANDLE
MOUNTAINS...SO AREAS OF BLOWING SNOW ARE EXPECTED ESPECIALLY FOR
ELEVATIONS ABOVE 3000 FEET. JW
&&
.AVIATION...
CONDITIONS WILL RAPIDLY DETERIORATE AT THE TAF SITES AS A STRONG
SYSTEM MOVES THROUGH THE AREA. VISIBILITIES AND CEILINGS WILL CRASH
FROM WEST TO EAST WITH A BURST OF MAINLY SN AND +SN MOVING THROUGH
THE AREA. TIMING OF WORST CONDITIONS WILL BE BTWN 09Z-19Z AT THE
TAF SITES WITH THE EARLIER ONSET FOR LOCATIONS NEAR THE CASCADES
AND A LATER ONSET OVER N IDAHO. BLSN IS ALSO EXPECTED AT KPUW BTWN
12-18Z. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 31 37 25 38 30 40 / 50 100 10 20 40 20
COEUR D`ALENE 30 38 27 39 30 40 / 20 100 20 20 50 20
PULLMAN 31 37 27 40 29 44 / 70 90 10 10 30 20
LEWISTON 35 42 31 47 32 49 / 50 80 20 10 20 20
COLVILLE 32 40 27 39 29 40 / 60 100 10 50 60 10
SANDPOINT 30 37 27 34 27 36 / 40 90 20 50 60 40
KELLOGG 29 33 28 33 29 37 / 20 100 70 20 50 30
MOSES LAKE 31 44 24 43 26 45 / 100 50 0 30 30 0
WENATCHEE 32 43 29 43 32 45 / 100 50 0 30 40 0
OMAK 31 43 22 41 29 45 / 100 90 0 70 80 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM PST SUNDAY FOR
NORTHERN PANHANDLE.
WINTER STORM WARNING FROM 4 AM TO 10 PM PST SUNDAY FOR IDAHO
PALOUSE.
WINTER STORM WARNING FROM 4 AM TO 10 PM PST SUNDAY FOR COEUR
D`ALENE AREA.
WINTER STORM WARNING FROM 4 AM SUNDAY TO 1 AM PST MONDAY FOR
CENTRAL PANHANDLE MOUNTAINS.
WA...WINTER WEATHER ADVISORY FROM 4 AM TO 4 PM PST SUNDAY FOR
NORTHEAST MOUNTAINS...SPOKANE AREA.
WINTER WEATHER ADVISORY UNTIL 10 AM PST SUNDAY FOR EAST SLOPES
NORTHERN CASCADES.
WINTER WEATHER ADVISORY UNTIL NOON PST SUNDAY FOR OKANOGAN
HIGHLANDS...OKANOGAN VALLEY.
WINTER WEATHER ADVISORY UNTIL NOON PST SUNDAY FOR UPPER COLUMBIA
BASIN...WATERVILLE PLATEAU.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM PST SUNDAY FOR
NORTHEAST BLUE MOUNTAINS.
WINTER WEATHER ADVISORY FROM 4 AM TO 4 PM PST SUNDAY FOR
WASHINGTON PALOUSE.
&&
$$
000
FXUS66 KSEW 220530
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
915 PM PST SAT NOV 21 2009
.SYNOPSIS...A DEEP LOW PRESSURE SYSTEM WILL MOVE INLAND ACROSS
SOUTHERN PORTIONS OF THE AREA LATE TONIGHT AND EARLY SUNDAY MORNING
BRINGING STRONG WINDS...RAIN AND HEAVY MOUNTAIN SNOW TO THE AREA. A
WEAKER FRONT WILL MOVE THROUGH THE AREA MONDAY AND MONDAY NIGHT. YET
ANOTHER WEAK FRONT WILL MOVE ACROSS THE AREA LATER IN THE WEEK.
&&
.SHORT TERM...THE MAIN ISSUES ARE IN THE SHORT TERM PERIOD...TONIGHT
AND EARLY SUNDAY...AS A DEEPENING LOW PRESSURE SYSTEM IN THE
NORTHERN OREGON OFFSHORE WATERS WINDS UP AND HEADS TOWARD THE
CENTRAL WASHINGTON COAST LATE TONIGHT. WITH A LACK OF BUOYS OR SHIP
REPORTS IN THE REGION OF STRONG CYCLOGENESIS...IT IS DIFFICULT TO
GET A FEEL FOR HOW STRONG THE SYSTEM IS AT THIS TIME. BUT INFRARED
IMAGERY APPEARS TO BE SHOWING THE DEVELOPMENT OF A CIRCULATION
CENTER IN THE VICINITY OF WHERE BUOY 46005 SHOULD
BE...45.7N/129W...THE PERIPHERY OF THE CENTER APPEARS TO SHOW GOOD
INSTABILITY WITH LOW TOPPED CONVECTION PARTIALLY RINGING IT...AND
THERE APPEARS TO BE HINTS AT THE DEVELOPMENT OF A BENT BACK
OCCLUSION TO THE WEST OF THE CENTER THAT APPEARS TO BE GETTING READY
TO PIVOT AROUND THE SW PORTION OF THE CENTER. WATER VAPOR IMAGERY
SHOWS GOOD DARKENING. 300 MB WINDS ALOFT SHOW VERY STRONG DIFFLUENCE
IN THE LEFT EXIT REGION OF A 150-170 KT ESE DIRECTED JET STREAK TO
THE WEST OF THE DEVELOPING CENTER. THE LATEST 00Z 12KM NAM AGREES
WITH EARLIER SOLUTIONS AND WITH THE 12Z 4KM MM5WRF AND THE INCOMING
00Z MM5NAM SOLUTIONS. THIS WOULD TAKE THE CENTER ONTO THE CENTRAL
COAST NEAR HOQUIAM BETWEEN 09Z AND 12Z THEN TAKE IT RAPIDLY EAST
THRU THE CHEHALIS GAP TO THE SOUTH PUGET SOUND AND INTO THE CENTRAL
CASCADES. THE GFS SOLUTIONS APPEAR MUSHED OUT AND TOO FAR NORTH WITH
THE CIRCULATION CENTER.
CONCERNING WIND...CURRENT WARNINGS AND ADVISORIES LOOK GOOD WITH
HIGH WIND WARNINGS ON THE CENTRAL COAST...IN THE ADMIRALTY INLET
AREA...AND IN THE CHEHALIS GAP AND SOUTHWEST INTERIOR WHERE THESE
AREAS WILL SEE STRONG SLY/SELY WINDS AHEAD OF THE LOW AND A PERIOD
OF STRONG W/NW WINDS BEHIND THE LOW. IN THE NORTHWEST INTERIOR ZONES
AROUND WESTERN WHATCOM COUNTY...THE SAN JUANS...AND WESTERN SKAGIT
COUNTY...HIGH WIND WARNINGS WILL EXPIRE AT MIDNIGHT AND ARE BEING
CAUSED BY A WARM FRONT OUT AHEAD OF THE DEVELOPING LOW. MANY AREAS
WILL SEE A BRIEF LULL IN THE WINDS AS THE BACK AROUND TO E/NE AHEAD
OF THE LOW...THEN SEE A VERY RAPID SURGE FROM THE WEST BEHIND THE
LOW. WILL KEEP AN EYE ON SATELLITE IMAGERY...IF THE STRENGTH OR
TRACK OF THE LOW CHANGES...WE MAY NEED TO UPGRADE SOME OF THE WIND
ADVISORIES TO WARNINGS. THE POST-LOW STRONG WINDS WILL NOT LAST
LONG...ONLY 3-4 HOURS OR SO AND WINDS ALL AREAS SHOULD RAPIDLY
DIMINISH AFTER 10 AM.
CONCERNING WINTER WEATHER...SNOW IS PICKING UP AT PARADISE RANGER
STATION AT MT RAINIER...BUT MOST PLACES HAVE YET TO REPORT MORE THAN
AN INCH OR TWO OVER THE PAST SEVERAL HOURS. EXPECT SNOWFALL RATES TO
PICK UP AS THE LOW APPROACHES...THEN CONTINUE FOR A FEW HOURS BEHIND
THE LOW WITH STRONG ONSHORE FLOW. THE WINTER STORM WARNINGS FOR THE
MOUNTAINS WILL BE CONTINUED...FOR THE COMBINATION OF SNOW AND WIND.
IF SNOWFALL RATES DONT PICK UP BY 10 PM...WE WILL UPDATE THE WARNING
FOR LOWER SNOW AMOUNTS...BUT STRONG WIND AND VERY LOW VISIBILITY FOR
A COUPLE HOURS AROUND THE PASSAGE OF THE LOW WILL STILL PRODUCE NEAR
BLIZZARD CONDITIONS IN THE MOUNTAINS LATE TONIGHT OR EARLY SUNDAY.
FLOW BEHIND THE SYSTEM APPEARS TOO STRONG TO PRODUCE A CONVERGENCE
ZONE SUNDAY...AND EXPECT SOME DRY AIR TO MIX DOWN WITH THE PASSING
JET STREAK SUNDAY. A BRIEF WEAK RIDGE OF HIGH PRES MOVES ACROSS THE
AREA SUN NIGHT. A WEAKER FRONTAL SYSTEM WILL PASS ACROSS THE AREA
LATER MON OR MON NIGHT. TUE AND TUE NIGHT NOW LOOK MORE TRANQUIL.
ALBRECHT
.LONG TERM...PREVIOUS LONG TERM DISCUSSION FOLLOWS...A WEAK UPPER
RIDGE WILL SETTLE IN OVER THE REGION TUESDAY AND WEDNESDAY WITH A
CHANCE OF RAIN IN THE FORECAST FOR TUESDAY AND WEDNESDAY. A WEAK
FRONT WILL SLOWLY MOVE ACROSS WESTERN WASHINGTON WEDNESDAY NIGHT AND
THURSDAY. THIS SYSTEM LOOKS TO BRING MORE PRECIPITATION TO THE AREA
THAN MONDAYS WEAK SYSTEM...MOSTLY DUE TO ITS SLOW TRANSITION ACROSS
WESTERN WASHINGTON...WHICH MIGHT BEAR SOME WATCHING AS WE MOVE INTO
EARLY NEXT WEEK. MEDIUM RANGE MODELS IN A BIT MORE AGREEMENT ON THE
FRONTAL WAVE THAT SLIDES INTO THE AREA THURSDAY NIGHT AND FRIDAY.
&&
.HYDROLOGY...THE ONLY HYDROLOGICALLY IMPORTANT PRECIPITATION THIS
EVENING IS TAKING PLACE AT LOWER ELEVATIONS OVER THE OLYMPIC
PENINSULA WHERE ABOUT 1-1.5 INCHES OF RAIN APPEARS TO HAVE FALLEN
SINCE ABOUT 21Z. ELSEWHERE PRECIPITATION HAS BEEN LIGHTER AND SNOW
LEVELS ARE BELOW 3000 FT. EXPECT OCCASIONALLY HEAVY RAIN TO CONTINUE
UNTIL THE LOW PASSES AROUND 12Z.
THE SKOKOMISH RIVER IS THE ONLY RIVER FLOODING AT THIS TIME. IT ROSE
BACK ABOVE FLOOD STAGE LATE THIS AFTERNOON PARTIALLY DUE TO RAINFALL
AND ALSO DUE TO PLANNED RELEASES TO 3000 CFS FROM CUSHMAN DAM NUMBER
2. IT WILL CREST AROUND 14Z SUNDAY AT ABOUT 16.9 FT...THEN FALL
SLOWLY THRU MONDAY. WITH COLDER CONDITIONS ALOFT AT THIS TIME AND
SOMEWHAT DRIER CONDITIONS OVER THE NEXT SEVERAL DAYS WITH
WEAKER...COOLER...AND PROGRESSIVE FRONTAL SYSTEMS AND LONGER BREAKS
BETWEEN SYSTEMS...OTHER RIVERS ACROSS WESTERN WASHINGTON SHOULD
REMAIN BELOW FLOOD STAGE FOR THE NEXT SEVERAL DAYS.
NO FLOODING IS EXPECTED AT ANY TIME ON THE GREEN RIVER. ALBRECHT
&&
.AVIATION...AN UPPER TROF WILL MOVE ACROSS THE AREA OVERNIGHT...AND
THEN OVER THE GREAT BASIN SUNDAY AFTERNOON. STRONG SW FLOW ALOFT...
BECOMING NW ON SUNDAY. A SURFACE LOW NOW ABOUT 175 MILES W OF THE
NRN OREGON COAST WILL CONTINUE MOVING RAPIDLY ENE. THIS LOW IS
EXPECTED TO TRACK OVER THE FAR S PUGET SOUND OR JUST S OF IT LATE
TONIGHT. STRONG ONSHORE OR WLY FLOW WILL THEN DEVELOP IN ITS WAKE.
MOIST AIR MASS WILL REMAIN OVER THE AREA...WITH CIGS MAINLY IN THE
1-3K FT RANGE...LIFTING INTO THE 4-6K FT RANGE SUNDAY. THE AIR MASS
WILL BECOME SLIGHTLY UNSTABLE ON SUNDAY FOR A SLIGHT CHANCE...ABOUT
10 PERCENT...OF TSTMS. A PUGET SOUND CONVERGENCE ZONE /PSCZ/ WILL
ALSO DEVELOP SUNDAY MORNING...NORTH OF THE SNOHOMISH/KING COUNTY
BORDER...AND THEN DRIFT S TO N OF KBFI IN THE AFTERNOON.
KSEA...WIND ABOVE THE SFC HAVE BACKED AROUND AND DROPPED OFF FASTER
THAN THE MODELS INDICATED...THUS IT APPEARED THAT LLWS WILL NO
LONGER BE A PROBLEM IN THE NEAR TERM. EXPECT WINDS TO INCREASE
DRAMATICALLY FROM THE SW ABOUT 12Z...IF THE SFC LOW TRACKS OVER THE
S SOUND. IF THE SFC LOW TRACKS FARTHER S...WINDS WILL BE LIGHT AND
VARIABLE OR LIGHT NLY...BEFORE KICKING UP OUT OF THE SW LATER IN THE
MORNING.
&&
.MARINE...AN OCCLUDED FRONT...EXTENDING FROM A NEAR 990 MB LOW S OF
THE QUEEN CHARLOTTES...WAS OFFSHORE. THIS FRONT WILL WEAKEN AND
SWING ACROSS THE NORTHERN WATERS OVERNIGHT. MEANWHILE...A RAPIDLY
DEEPENING LOW NOW ABOUT 150 NM OFF THE NORTHERN OREGON COAST WILL
MOVE ACROSS THE CENTRAL COASTAL WATERS AND FAR SOUTH PUGET SOUND
LATE TONIGHT. THIS LOW WILL RESULT IN STORM FORCE SOUTH WINDS OVER
THE CENTRAL COASTAL WATERS TONIGHT. EXPECT STRONG WESTERLY FLOW TO
DEVELOP EARLY SUNDAY FOR GALE FORCE WESTERLY WINDS ACROSS A PORTION
OF THE WATERS. A BRIEF PERIOD OF STORM FORCE WINDS MAY OCCUR OVER
THE CENTRAL STRAIT OF JUAN DE FUCA SUNDAY MORNING WITH THE INITIAL
PUSH. THE ONSHORE FLOW WILL WEAKEN SUNDAY NIGHT.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WARNINGS REMAIN IN EFFECT FOR PORTIONS OF WESTERN
WASHINGTON.
.WINTER STORM WARNING IN EFFECT FOR THE OLYMPIC MOUNTAINS
UNTIL 4 AM PST SUNDAY AND FOR THE CASCADES FROM UNTIL
1 PM PST SUNDAY.
.HIGH WIND WARNING FOR THE CENTRAL WASHINGTON COAST...THE
LOWER CHEHALIS VALLEY...SOUTHWEST INTERIOR AND
ADMIRALTY INLET AREA THROUGH 10 AM SUNDAY.
.HIGH WIND WARNING FOR THE NORTH INTERIOR OF WESTERN
WASHINGTON THROUGH MIDNIGHT TONIGHT.
.WIND ADVISORY FOR THE CENTRAL PUGET SOUND AREA AND STRAIT
OF JUAN DE FUCA ZONES MIDNIGHT TONIGHT THROUGH SUNDAY
MORNING.
PZ...A STORM WARNING IS IN EFFECT FOR THE CENTRAL COASTAL WATERS
WATERS UNTIL 1 AM SUNDAY.
.GALE WARNINGS ARE IN EFFECT FOR THE REMAINING WATERS.
.A SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR
CONDITIONS IS IN EFFECT TIL 4 PM MON.
$$
WWW.WEATHER.GOV/SEATTLE
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.
000
FXUS66 KOTX 220458
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
858 PM PST SAT NOV 21 2009
.SYNOPSIS...
A STRONGER AND COLDER STORM SYSTEM WILL BRING THE POTENTIAL FOR
MODERATE TO HEAVY SNOWFALL OVER MUCH OF THE REGION TONIGHT AND
SUNDAY. A SERIES OF STORM SYSTEMS WILL CONTINUE TO PASS THROUGH
THE INLAND NORTHWEST EVERY 24 TO 36 HOURS THROUGH AT LEAST THE
MIDDLE OF NEXT WEEK.
&&
.DISCUSSION...
MINOR FORECAST CHANGES HAVE BEEN MADE FOR THE REST OF TONIGHT. THE
STRONG PACIFIC SYSTEM IN ON TRACK TO BRING RAIN AND SNOW TO THE
AREA WITH SEVERAL WINTER WEATHER ADVISORIES AND WINTER STORM
WARNINGS IN EFFECT. CHANGES TONIGHT WERE TO SLIGHTLY SLOW THE
TIMING OF THE INCOMING SYSTEM WITH PRECIPITATION CHANCES LOWERED
THROUGH 12Z OVER NE WA/N IDAHO. ALSO BASED ON FCST SOUNDINGS AND
PRECIPITATION INTENSITY RAIN SHOULD CHANGE OVER TO SNOW IN THE LOWER
PORTIONS OF THE OKANOGAN VALLEY OVERNIGHT SO THE ADVISORY WAS
UPDATED TO INCLUDE THE LOWER PORTION OF THE VALLEY INCLUDING OMAK.
A MORE DETAILED DISCUSSION ON THIS SYSTEM WILL BE SENT NEAR OR
SHORTLY AFTER 10 PM WITH THE AVIATION DISCUSSION UPDATE. JW
&&
.AVIATION...
FROM PREVIOUS DISCUSSION...A WEAK RIDGE ALOFT WILL PROMOTE VFR
CONDITIONS AT ALL TAF SITES THROUGH 03Z TONIGHT...WITH LINGERING
SNOW SHOWERS LOCALLY OBSCURING MOUNTAINS IN THE IDAHO PANHANDLE
AND CASCADE CREST. THE NEXT PACIFIC STORM SYSTEM WILL SPREAD IFR
CEILINGS TO THE WESTERN REACHES OF THE REGION AFTER
04Z...SPREADING INTO THE EASTERN TERMINALS AFT 10Z. THE INCOMING
STORM SYSTEM WILL ALSO TIGHTEN PRESSURE GRADIENTS LEADING TO
INCREASING WINDS FROM KPUW- KGEG WITH GUSTS OF 25-35KTS. THE
PRECIPITATION WILL BEGIN TO WANE FROM THE WEST AFTER 18Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 31 37 25 38 30 40 / 50 100 10 20 40 20
COEUR D`ALENE 30 38 27 39 30 40 / 20 100 20 20 50 20
PULLMAN 31 37 27 40 29 44 / 70 90 10 10 30 20
LEWISTON 35 42 31 47 32 49 / 50 80 20 10 20 20
COLVILLE 32 40 27 39 29 40 / 60 100 10 50 60 10
SANDPOINT 30 37 27 34 27 36 / 40 90 20 50 60 40
KELLOGG 29 33 28 33 29 37 / 20 100 70 20 50 30
MOSES LAKE 31 44 24 43 26 45 / 100 50 0 30 30 0
WENATCHEE 32 43 29 43 32 45 / 100 50 0 30 40 0
OMAK 31 43 22 41 29 45 / 100 90 0 70 80 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM PST SUNDAY FOR
NORTHERN PANHANDLE.
WINTER STORM WARNING FROM 4 AM TO 10 PM PST SUNDAY FOR IDAHO
PALOUSE.
WINTER STORM WARNING FROM 4 AM TO 10 PM PST SUNDAY FOR COEUR
D`ALENE AREA.
WINTER STORM WARNING FROM 4 AM SUNDAY TO 1 AM PST MONDAY FOR
CENTRAL PANHANDLE MOUNTAINS.
WA...WINTER WEATHER ADVISORY FROM 4 AM TO 4 PM PST SUNDAY FOR
NORTHEAST MOUNTAINS...SPOKANE AREA.
WINTER WEATHER ADVISORY UNTIL 10 AM PST SUNDAY FOR EAST SLOPES
NORTHERN CASCADES.
WINTER WEATHER ADVISORY UNTIL NOON PST SUNDAY FOR OKANOGAN
HIGHLANDS...OKANOGAN VALLEY.
WINTER WEATHER ADVISORY UNTIL NOON PST SUNDAY FOR UPPER COLUMBIA
BASIN...WATERVILLE PLATEAU.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM PST SUNDAY FOR
NORTHEAST BLUE MOUNTAINS.
WINTER WEATHER ADVISORY FROM 4 AM TO 4 PM PST SUNDAY FOR
WASHINGTON PALOUSE.
&&
$$
000
FXUS66 KPQR 220442
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
841 PM PST SAT NOV 21 2009
.SYNOPSIS...A STRONG PACIFIC COLD FRONT WILL MOVE INLAND OVERNIGHT AS
A DEEP SURFACE LOW OFF THE COAST MOVES NORTHEAST INTO WASHINGTON.
A WEAK RIDGE OF HIGH PRESSURE WILL FOLLOW SUNDAY AFTERNOON AND
NIGHT...BEFORE THE NEXT FRONTAL SYSTEM ARRIVES LATER ON MONDAY.
&&
.SHORT TERM...MODELS ARE IN REASONABLY GOOD AGREEMENT SHOWING THE
DEEP SURFACE LOW MOVING ONTO THE CENTRAL WA COAST OR POSSIBLY A BIT S
AROUND 09Z. HOWEVER AT 00Z MODELS WERE ABOUT 4 MB TOO HIGH COMPARED
WITH SHIP REPORTS W OF 130W NEAR THE LOW. MODELS ARE IN GOOD
AGREEMENT ON THE UPPER FEATURES...WITH A STRONG SHORTWAVE MOVING
ACROSS THE FORECAST AREA TONIGHT...DIGGING SLIGHTLY TO THE ESE.
TIMING OF THE COLD FRONT IN ALL MODELS INDICATES FRONTAL PASSAGE ON
THE COAST AROUND MIDNIGHT. HAVE ISSUED A HIGH WIND WARNING FOR THE
WILLAPA HILLS TO GO ALONG WITH THE COASTAL WARNING AND INLAND VALLEY
WIND ADVISORIES. WINDS INLAND LOOK GUSTY WITH THE FRONT BUT
ESPECIALLY AFTER THE FRONT AND LOW MOVE INLAND AS THERE WILL BE
STRONG PRES RISES IN THE OVERNIGHT HOURS.
DOPPLER RADAR SHOWS THE PRECIP FIELD HAS FINALLY SPREAD TO THE
CASCADES THIS EVENING. WILL CONTINUE THE WINTER STORM WARNING FOR THE
CASCADES AS MOISTURE...STRENGTH OF THE FRONT AND THE POST FRONTAL
WESTERLY OROGRAPHIC FLOW ALL FAVOR SIGNIFICANT SNOWFALL FOR LATER
TONIGHT AND SUN.
A WEAK UPPER RIDGE WILL BUILD OVER THE FORECAST AREA SUN NIGHT AND
MON FOLLOWING THE FRONT. BEST CHANCES FOR PRECIP MON AND TUE WILL
SHIFT N INTO WA WITH WARM FRONT OVERRUNNING. THE UPPER RIDGE HOLDS
COLD FRONT AT BAY UNTIL AFTER TUE NIGHT. RW
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...WEAK HIGH PRES
RIDGE OVER THE FORECAST AREA CONTINUES TO
PUSH ENERGY NORTH OF FORECAST AREA MID WEEK. IT MANAGES TO DELAY THE
ARRIVAL OF A SECOND SYSTEM THROUGH THUR. MODEL SOLUTIONS DIVERGE
TOWARD THE END OF THE WEEK AND HAVE LITTLE CONFIDENCE IN THEM. AT
THIS TIME WILL GO WITH CLIMATOLOGY UNTIL THERE IS SOME CONSISTENCY
BETWEEN THE MODELS..
&&
.AVIATION...AREAS OF MVFR CONDITIONS ALONG THE COAST THIS EVENING
WILL EXPAND INLAND TONIGHT AS THE RAIN SHIELD FROM THE NEXT STRONG
SYSTEM APPROACHES. SOUTH WINDS WILL INCREASE THROUGH 09Z AND THEN
TURN WESTERLY FROM WEST TO EAST AS THE ASSOCIATED STRONG COLD FRONT
SWINGS ACROSS THE AREA. A MIX OF VFR AND MVFR CONDITIONS ARE
EXPECTED SUNDAY MORNING IN STRONG UNSTABLE ONSHORE FLOW.
KPDX AND APPROACHES...VFR CONDITIONS ARE EXPECTED THROUGH 06Z...THEN
MVFR CONDITIONS WILL DEVELOP AS A COLD FRONT APPROACHES. SOUTH TO
SOUTHWEST WINDS MAY BECOME QUITE STRONG AROUND 12Z AS A STRONG
GRADIENT DEVELOPS OVER THE NORTH VALLEY AS THE LOW MOVES INLAND.
WIND GUSTS NEAR 50 MPH ARE POSSIBLE. A MIX OF VFR AND MVFR
CONDITIONS ARE EXPECTED SUNDAY MORNING IN STRONG UNSTABLE ONSHORE
FLOW.
&&
.MARINE...GALE FORCE SOUTH WINDS WILL STRENGTHEN TO STORM FORCE
LATER THIS EVENING AS A POTENT LOW MOVES NORTH OF THE COASTAL WATERS
AND INLAND ALONG THE WASHINGTON COAST. WINDS WILL TURN W TO NW ON
SUNDAY AND BEGIN EASING. SEAS TONIGHT WILL LIKELY PEAK AROUND 20 FT
...BUT WILL DROP QUICKLY TO THE MID TEENS ON SUN.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...STORM WARNING FOR THE COASTAL WATERS FROM CAPE SHOALWATER TO
FLORENCE THROUGH 3 AM SUNDAY MORNING.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR CONDITIONS
THROUGH SUN EVENING.
WINTER STORM WARNING FOR THE S WA AND N AND CENTRAL OREGON
CASCADES TONIGHT AND SUNDAY.
HIGH WIND WARNING FOR THE S WA/N AND CENTRAL OREGON COAST...
AND WILLAPA HILLS TONIGHT.
WIND ADVISORY FOR THE WILLAMETTE VALLEY...THE LOWER
COLUMBIA...AND THE I-5 CORRIDOR FOR THIS EVENING
THROUGH SUNDAY MORNING.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KSEW 212357 AAA
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
400 PM PST SAT NOV 21 2009
.SYNOPSIS...A VIGOROUS FRONTAL SYSTEM WILL MOVE THROUGH WESTERN
WASHINGTON THIS AFTERNOON AND EVENING BRINGING STRONG WINDS...RAIN
AND HEAVY MOUNTAIN SNOW TO THE AREA INTO SUNDAY. A WEAKER FRONT WILL
MOVE THROUGH THE AREA MONDAY AND MONDAY NIGHT...AND ANOTHER WEAK
FRONT WILL LATER IN THE WEEK.
&&
.SHORT TERM...A WARM FRONT WILL LIFT ACROSS WESTERN WASHINGTON EARLY
THIS EVENING FOLLOWED BY AN OCCLUDED FRONT AND SURFACE LOW LATE
TONIGHT INTO THURSDAY MORNING. MESOSCALE MODELS ADVERTISING A MORE
SOUTHERLY TRACK FOR THE THE SURFACE LOW...MOVING ONSHORE NEAR KHQM
JUST AFTER MIDNIGHT TONIGHT...THEN NORTHEAST INTO THE SOUTH SOUND
AND THEN EAST OF THE CASCADES BY LATE SUNDAY MORNING. THIS
WILL PRODUCE WINDY CONDITIONS ACROSS THE AREA. STRONGEST WINDS WILL
LIKELY COME AS A ONE TWO PUNCH WITH THE SOUTHERLIES AHEAD OF THE LOW
AND OCCLUDED FRONT TONIGHT...AND AGAIN WITH THE WESTERLIES BEHIND
THE LOW AND FRONT AS THEY TRACK INLAND EARLY SUNDAY MORNING. SOME
AREAS LIKE THE COAST...ADMIRALTY INLET...NORTH INTERIOR WILL
EXPERIENCE BOTH PERIODS OF STRONG WINDS...MOST OTHER AREAS WILL
EXPERIENCE THE STRONGEST WINDS WITH AND BEHIND THE FRONT LATE
TONIGHT INTO EARLY SUNDAY MORNING. WINDS SHOULD BEGIN TO COME DOWN
BY LATE SUNDAY MORNING AND INTO THE AFTERNOON HOURS ALL AREAS.
THE SNOW LEVEL WILL CONTINUE TO RISE TO AROUND 3000 FT TONIGHT AS
THE WARM FRONT LIFTS OVER THE AREA...FALLING AGAIN TO AROUND 2000 FT
TOMORROW MORNING AS THE OCCLUDED FRONT PUSHES THROUGH. BOTH FRONTS
WILL BRING SIGNIFICANT PRECIPITATION TO THE COAST...OLYMPICS AND
CASCADES TONIGHT THROUGH SUNDAY MORNING. HEAVY SNOW FOR THE
MOUNTAINS REMAINS ON TRACK WITH IMPRESSIVE PRECIPITATION AMOUNTS
THROUGH SUNDAY MORNING FOR THE OLYMPICS...3 TO 4 INCHES...AND THE
CASCADES...1 TO 3 INCHES. EVEN WITH THE RISE OF SNOW LEVELS TO
AROUND 3000 FT...30 TO 40 INCHES OF SNOW ARE EXPECTED FOR THE
OLYMPICS AND 10 TO 30 INCHES FOR THE CASCADES. EVEN THE RELATIVELY
DRIER HURRICANE RIDGE AREA SHOULD RECEIVE WINTER STORM WARNING
AMOUNTS...12 INCHES IN 12 HOURS OR 18 INCHES IN 24 HOURS.
FLOW IS STRONG ENOUGH THROUGH THE DAY TOMORROW THAT CONVERGENCE ZONE
IS UNLIKELY...WITH MOST OF THE POST-FRONTAL SHOWERS PUSHED UP ONTO
THE MOUNTAINS. SHOWERS WILL TAPER OFF SUNDAY AFTERNOON EVENING AS
THE UPPER RIDGE MOVES OVERHEAD. THE RIDGE KICKS EAST QUICKLY MONDAY
AHEAD OF ANOTHER FRONTAL SYSTEM. THIS NEXT SYSTEM COULD STILL BRING
DECENT PRECIPITATION AMOUNTS TO THE COAST AND OLYMPIC PENINSULA
MONDAY AFTERNOON...BUT WEAKENS AS IT MOVES INLAND MONDAY NIGHT.
COMPARED TO LAST SEVERAL SYSTEMS THIS WILL BE AN UNEVENTFUL
SYSTEM...MARKING THE BEGINNING OF A PERIOD OF QUIETER WEATHER. COOK
.LONG TERM...A WEAK UPPER RIDGE WILL SETTLE IN OVER THE REGION
TUESDAY AND WEDNESDAY WITH A CHANCE OF RAIN IN THE FORECAST FOR
TUESDAY AND WEDNESDAY. A WEAK FRONT WILL SLOWLY MOVE ACROSS WESTERN
WASHINGTON WEDNESDAY NIGHT AND THURSDAY. THIS SYSTEM LOOKS TO BRING
MORE PRECIPITATION TO THE AREA THAN MONDAYS WEAK SYSTEM...MOSTLY DUE
TO ITS SLOW TRANSITION ACROSS WESTERN WASHINGTON...WHICH MIGHT BEAR
SOME WATCHING AS WE MOVE INTO EARLY NEXT WEEK. MEDIUM RANGE MODELS
IN A BIT MORE AGREEMENT ON THE FRONTAL WAVE THAT SLIDES INTO THE
AREA THURSDAY NIGHT AND FRIDAY.
&&
.HYDROLOGY...TODAYS SYSTEM WILL BRING IMPRESSIVE AMOUNTS OF
PRECIPITATION TO THE CASCADES AND OLYMPICS...BUT RELATIVELY LOW SNOW
LEVELS WILL MITIGATE THE IMPACT ON WESTERN WASHINGTON RIVERS EXCEPT
THE SKOKOMISH RIVER WHICH IS ALREADY AT OR NEAR FLOOD STAGE GOING
INTO THIS EVENT. THE SNOW LEVEL WILL ONLY RISING TO AROUND 3000 FT
TONIGHT...AND THEN FALL SUNDAY TO AROUND 2000 FT...MAKING THIS
MOSTLY A MOUNTAIN SNOW EVENT AND NOT A RAIN EVENT.
THE SKOKOMISH RIVER FELL TO JUST BELOW FLOOD STAGE EARLY SATURDAY
AFTERNOON. NEW FORECAST GUIDANCE SHOWS THE RIVER RISING AGAIN TO
JUST BELOW 17 FEET BY EARLY SUNDAY MORNING. IN ADDITION...THERE HAS
BEEN PLANNED RELEASE OF 3000 CFS FROM CUSHMAN DAM #2 INTO THE NORTH
FORK SKOKOMISH RIVER THIS AFTERNOON. HAVE ACCORDINGLY EXTENDED THE
WARNING FOR THE SKOKOMISH INTO MONDAY.
GUIDANCE AND OBSERVATIONS FOR THE LOWER REACH OF THE CHEHALIS RIVER
IN GRAYS HARBOR COUNTY CONTINUE TO SUPPORT THE IDEA THAT IT WILL
REMAIN WELL BELOW FLOOD STAGE SO HAVE ACCORDINGLY ENDED THE FLOOD
WATCH.
MONDAYS WEAKER SYSTEM LOOKS TO BE PROGRESSIVE ENOUGH TO BE OF LITTLE
CONCERN WITH RESPECT TO FLOODING. THE AIR MASS OVER THE NORTHWEST
FOR THE REMAINDER OF THE WEEK WILL BE WARMER WITH HIGHER SNOW
LEVELS...HOWEVER THE SYSTEMS THAT ARE EXPECTED TO AFFECT THE AREA
WILL BE FAIRLY WEAK AND ARE NOT EXPECTED TO CAUSE ANY ADDITIONAL
FLOODING CONCERNS.
NO FLOODING IS EXPECTED AT ANY TIME ON THE GREEN RIVER. COOK
&&
.AVIATION...A WARM/OCCLUDED FRONT JUST OFFSHORE THIS AFTERNOON WILL
LIFT ACROSS WRN WA EARLY THIS EVENING. SLY FLOW ALOFT WILL BECOME
STRONG. THE ATMOSPHERE WILL BE STABLE AND MOIST WITH RAIN INCREASING
ACROSS THE AREA. SURFACE GRADIENTS BECOME MORE ELY OVERNIGHT WITH
STRONG SLY FLOW JUST OFF THE SURFACE CREATING THE POTENTIAL FOR
LLWS. TAFS WERE UPDATED EARLIER TO INCLUDE THIS FOR MOST
TERMINALS...GENERALLY IN THE 02Z-12Z TIME FRAME.
SURFACE LOW PRESSURE WILL DEEPEN TO AROUND 985-990 MB TONIGHT AND
TRACK INTO SRN WA NEAR KHQM ARND 12Z. STRONG PRESSURE RISES ARE
EXPECTED BEHIND THE LOW FROM THE CENTRAL COAST EWD INTO THE SW
INTERIOR WHICH WILL RESULT IN A BURST OF STRONG WINDS SOMETIME
BETWEEN 12-16Z SUN MORNING. THE ATMOSPHERE WILL BE SOMEWHAT UNSTABLE
NEAR THE LOW CENTER...ALLOWING WINDS ALOFT TO MIX DOWN TO THE
SURFACE IN GUSTS. A BURST OF WIND DOWN THE STRAIT WILL ALSO DEVELOP
SUN MORNING.
KSEA...LLWS IS POSSIBLE FROM AROUND 02Z-12Z AS SURFACE GRADIENTS
BECOME ELY AND SLY FLOW OF 30-40 KT DEVELOPS AROUND 2K FT.
OTHERWISE...RAIN WILL INCREASE THIS EVENING WITH MVFR CONDITIONS
EXPECTED. SLY WINDS AROUND 10 KT THROUGH TONIGHT...BUT A DRAMATIC
JUMP IN SW WINDS IS ANTICIPATED AFTER 12Z AS A SURFACE LOW TRACKS
INLAND NEAR OR SOUTH OF KSEA. SW WINDS OF 20-30 KT WITH HIGHER GUSTS
ARE POSSIBLE FROM 12-16Z. DTM
&&
.MARINE...WINDS ARE SLOWLY PICKING UP ACROSS WRN WA IN ADVANCE OF A
WARM/OCCLUDED FRONT JUST OFFSHORE. THE 12Z 4KM MM5 CAME IN MUCH
STRONGER AND WIDESPREAD WITH 40 KT WINDS ACROSS THE N INTERIOR. THE
HIGH END GALE WARNING FOR THAT AREA LOOKS GOOD THROUGH THIS EVENING.
GALES WILL ALSO DEVELOP ON THE COAST WHICH WILL EXTEND INTO SUN
MORNING WITH A SECOND BURST OF WINDS WITH THE SURFACE LOW. THE MM5
IS SHOWING WIDESPREAD 40 KT THERE AS WELL WHICH IS SHORT OF STORM
FORCE...SO I WILL MAINTAIN THE HIGH END GALE.
A POTENTIALLY STRONG 985-990 MB SURFACE LOW WILL ENTER THE COASTAL
WATERS AFTER 09Z TONIGHT AND TRACK INTO THE CENTRAL/S WA COAST
AROUND 12Z. WINDS BEHIND THE FRONT WILL RISE DRASTICALLY WITH HIGH
END GALES EXPECTED THROUGH SUN MORNING ACROSS THE COASTAL
WATERS...ESPECIALLY OVER THE SOUTH/CENTRAL PORTIONS. A 3-4 HOUR
BURST STRONG WLY WINDS DOWN THE STRAIT INTO THE WHIDBEY ISLAND AND
ADMIRALTY INLET AREA IS ALSO EXPECTED AFTER 12Z. DTM
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WARNINGS REMAIN IN EFFECT FOR PORTIONS OF WESTERN
WASHINGTON...
WINTER STORM WARNING IN EFFECT FOR THE OLYMPIC MOUNTAINS TO 4
AM PST SUNDAY AND FOR THE CASCADES FROM TO 1 PM PST
SUNDAY...
HIGH WIND WARNING FOR THE CENTRAL AND SOUTH WASHINGTON
COAST...LOWER CHEHALIS VALLEY...SOUTHWEST INTERIOR...AND
ADMIRALTY INLET AREA THROUGH 10 AM SUNDAY...
HIGH WIND WARNING FOR THE NORTH INTERIOR OF WESTERN WASHINGTON
THROUGH MIDNIGHT TONIGHT...
WIND ADVISORY FOR THE CENTRAL PUGET SOUND AREA AND STRAIT OF
JUAN DE FUCA ZONES MIDNIGHT TONIGHT THROUGH SUNDAY MORNING...
PZ...A GALE WARNING IS IN EFFECT FOR THE COASTAL WATERS...ADMIRALTY
INLET AND THE ENTRANCES TO THE STRAIT OF JUAN DE FUCA THROUGH
SUNDAY MORNING.
.A GALE WARNING IS IN EFFECT FOR THE NORTHERN INLAND WATERS
THROUGH MIDNIGHT TONIGHT.
.A GALE WARNING IS IN EFFECT FOR THE CENTRAL STRAIT FROM LATE
TONIGHT THROUGH SUNDAY MORNING.
.A SMALL CRAFT ADVISORY IS IN EFFECT FOR PUGET SOUND THROUGH
SUNDAY MORNING.
$$
WWW.WEATHER.GOV/SEATTLE
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.
000
FXUS66 KOTX 212341 AAA
AFDOTX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SPOKANE WA
341 PM PST SAT NOV 21 2009
.SYNOPSIS...
A STRONGER AND COLDER STORM SYSTEM WILL BRING THE POTENTIAL FOR
MODERATE TO HEAVY SNOWFALL OVER MUCH OF THE REGION TONIGHT AND
SUNDAY. A SERIES OF STORM SYSTEMS WILL CONTINUE TO PASS THROUGH
THE INLAND NORTHWEST EVERY 24 TO 36 HOURS THROUGH AT LEAST THE
MIDDLE OF NEXT WEEK.
&&
.DISCUSSION...
...LIGHT TO MODERATE SNOWFALL EXPECTED TONIGHT THROUGH SUNDAY
ACROSS THE INLAND NW...
TONIGHT THROUGH SUNDAY...AFTERNOON WATER VAPOR SHOWING A STRONG
PACIFIC STORM CHARGING TOWARD THE WASHINGTON COAST WITH A CLASSIC
BAROCLINIC LEAF SIGNATURE INDICATIVE OF THE ORGANIZED DEEPENING
SURFACE CYCLONE AND ASSOCIATED CONVEYOR BELTS. MODELS HAVE COME INTO
BETTER AGREEMENT REGARDING THE INCOMING STORM SYSTEM WHICH NOW
TRACK THE SURFACE LOW OVER THE KITTITAS VALLEY...ALONG THE I-90
CORRIDOR...BEFORE TRACKING TO THE NORTHEAST ACROSS THE NORTHERN
IDAHO PANHANDLE INTO SOUTHEASTERN BRITISH COLUMBIA. THE LOW WILL
BOTTOM OUT THIS EVENING WHILE CROSSING ONTO THE WASHINGTON COAST
JUST BELOW 990MB...THEN GRADUALLY FILL AND WEAKEN OVERNIGHT INTO
TOMORROW. THE HEAVIEST PRECIPITATION OVERNIGHT WILL FOCUS ALONG
THE CASCADES...WATERVILLE PLATEAU...OKANOGAN REGION...AS THE LOW
NEARS THE COAST TONIGHT AND INCREASING EASTERLY FLOW ENHANCES LIFT
UNDER A BLANKET OF DEEP ISENTROPIC ASCENT. AS THE LOW JUMPS THE
CASCADES AFT 12Z SUNDAY...THE PRECIPITATION SHIELD WILL BEGIN TO
SHIFT TOWARD FAR EASTERN WASHINGTON AND IDAHO. RADAR IMAGERY WILL
LIKELY ILLUSTRATE A WELL DEFINED DEFORMATION BAND ALONG THE
NORTHERN PERIPHERY OF THE LOW WHICH IS WHERE THE 6 HOUR LIQUID
AMTS WILL NEAR THREE-TENTHS OF AN INCH THEN AS THE LOW EJECTS TO
NORTHEAST MIDDAY TOMORROW...CONTINUED STRONG UPSLOPE INTO THE ID
PANHANDLE WILL RESULT IN THE SECOND CHANCE FOR MODERATE
PRECIPITATION RATES...MAINLY FOCUSING INTO THE PANHANDLE
MTNS...IDAHO PALOUSE...AND COEUR D ALENE AREA. SNOWFALL TOTALS
WILL GENERALLY RUN 2-5 INCHES IN THE VALLEYS WITH 6-10" IN THE
MOUNTAINS. WITH THE HIGHEST TOTALS ACROSS THE CENTRAL ID PANHANDLE
AS THE SECOND WAVE OF PRECIPITATION FORMS IN THE WAKE OF THE LOW.
THIS IS WHERE WINTER WEATHER WARNINGS WERE POSTED AND VALLEYS CAN
EXPECT 3-6" WITH 8-10" IN THE MOUNTAINS.
CURRENT OBSERVATIONS FROM THE EAST SLOPES...OKANOGAN HIGHLANDS...AND
WENATCHEE AREA SUGGEST TEMPERATURES HAVE WARMED INTO THE MID TO
UPPER 40`S BELOW 2000` WITH DEWPOINTS IN THE UPPER 20`S TO LOWER
30`S. CALCULATED WETBULB COOLING SUGGEST TEMPERATURES WILL REMAIN
IN THE MID TO UPPER 30`S WITH THE ONSET OF PRECIPITATION SO ALL
WINTER HIGHLIGHTS IN THE AFOREMENTIONED ZONES WERE FOCUSED MAINLY
ABOVE 2000`.
WINDS WILL BE BREEZY THROUGH THE PERIOD WITH THE HIGHEST GUSTS
EXPECTED SUNDAY AFTERNOON UNDER THE COLD ADVECTION REGIME. MODELS
CONTINUE TO HINT 850MB WINDS OF 35-50KTS DOWN THE EAST SLOPES AND
THIS WILL NEED TO BE MONITORED CLOSELY. THESE BREEZY WINDS WILL
ALSO CAUSE AREAS OF BLOWING SNOW AT TIMES BUT WITH THE SNOW BEING
OF A WETTER NATURE...EXPECT THIS WILL BE LOCALIZED. /SB
SUNDAY NIGHT THROUGH TUESDAY NIGHT...MODEL GUIDANCE IS IN GOOD
AGREEMENT THAT THE PERIOD WILL BEGIN ON A QUIETING NOTE AS
SUNDAYS UPPER LEVEL TROF SHIFTS INTO CENTRAL MONTANA. THE TROF
WILL BE SLOWLY REPLACED BY A WELL-DEFINED UPPER LEVEL RIDGE
RESULTING IN RAPID STABILIZATION OVER THE ENTIRE REGION. THUS THE
POST-FRONTAL SHOWERS OVER THE IDAHO PANHANDLE DUE TO MOIST UPSLOPE
SW FLOW WILL DECREASE RAPIDLY. MODEL CROSS SECTIONS SHOW THE
POTENTIAL INSTABILITY DECREASING FROM AROUND 550 MBS AT 00Z TO
LESS THAN 700 MBS BY 12Z. MEANWHILE RELATIVE HUMIDITY VALUES
DECREASE RAPIDLY ABOVE 700 MBS AS WELL. THIS SUGGESTS THAT MOST OF
THE POST-FRONTAL SHOWER ACTIVITY OVER THE CENTRAL PANHANDLE WILL
DECREASE AFTER 06Z WITH ONLY A FEW PERSISTENT SHOWERS .
GENERALLY DRY WEATHER WILL THEN PERSIST THROUGH MOST OF MONDAY UNTIL
ANOTHER FRONT PUSHES INTO WESTERN WASHINGTON LATE IN THE DAY.
MOISTURE ASSOCIATED WITH THIS DISTURBANCE WAS CURRENTLY LOCATED
JUST WEST OF 150W AND WAS ADEQUATELY HANDLED BY BOTH THE GFS AND
ECMWF AS OF 22Z. BOTH MODEL SOLUTIONS BRING THE PRE-FRONTAL UPPER
LEVEL RIDGE INTO NORTH IDAHO BY 00Z TUE WITH A SWIFT MOVING
SHORTWAVE TROF PASSING THROUGH THE SOUTHERN THIRD OF BC OVERNIGHT.
THIS SYSTEM SHOULD BE MUCH LESS DYNAMIC AND IMPRESSIVE THAN THE
ONE EXPECTED TONIGHT AND SUNDAY. IN FACT...THE MODELS HAVE BEEN
TRENDING TOWARD KEEPING THE PRECIPITATION FAIRLY LIGHT WITH MOST
OF IT HOLDING OVER THE NORTHERN THIRD OF THE CWA. GIVEN THE TRACK
OF THE UPPER LEVEL TROF...THE PRIMARY FLOW IN THE 850-700 MB LAYER
WILL REMAIN OUT OF THE WEST SO WITHOUT THE BENEFIT OF A STRONG
WARM FRONT OR ISENTROPIC ASCENT WE WOULD ALSO EXPECT TO SEE A FAIR
AMOUNT OF DOWNSLOPE FLOW OVER THE CASCADES. WHILE BOTH THE GFS AND
ECMWF DO HINT AT A WEAK WARM AIR ADVECTION PATTERN IN THE 850-700
MB LAYER ITS NOT NECESSARILY ENOUGH TO OVERCOME THE DOWNSLOPE
IMPACTS OF THE CASCADES. WHILE THIS SYSTEM WONT HAVE THE BENEFIT
OF STRONG DYNAMICAL FORCING IT WILL FEATURE A HIGH AMOUNT OF
MOISTURE...AS EVIDENCED BY PRECIPITABLE WATER VALUES AROUND
150-180 PERCENT OF NORMAL. THERE WILL ALSO BE PERSISTENT WEAK
ISENTROPIC ASCENT. WHATS INTERESTING IN THIS SCENARIO IS THE FRONT
LOSES MUCH OF ITS EASTWARD MOMENTUM AS YET ANOTHER SYSTEM PUSHES
INTO THE COAST BY LATE TUESDAY. THIS NEXT SYSTEM AMPLIFIES YET
ANOTHER SHORTWAVE RIDGE OVER THE AREA...WHICH ALLOWS THE MONDAY
FRONT TO SIT AND GRADUALLY WEAKEN OVER THE REGION AND SHIFT SLOWLY
SOUTH THROUGH TUESDAY . GIVEN THIS SCENARIO WE WOULD EXPECT TO SEE
A LIGHT AND RATHER PROLONGED STRATIFORM PRECIPITATION EVENT MUCH
OF WHICH WILL FALL AS SNOW. GIVEN THE WEAK FORCING WE PREFER THE
DRIER GFS AND ECMWF SOLUTIONS OVER THE RATHER WET NAM. AT THIS
POINT IT APPEARS WINTER HIGHLIGHTS WILL NOT BE NECESSARY. MOST OF
THE PRECIPITATION IS EXPECTED TO FALL NORTH OF I90. FX
WEDNESDAY TO SATURDAY...THE MEDIUM-RANGE STARTS WITH A RIDGE OVER
THE WEST...A WARM FRONT NR THE BC BORDER AND A COLD FRONT NR 130W.
THIS LEAVES PASSING MID/HIGHER CLOUDS AND A CHANCE OF RAIN AND SNOW
ACROSS THE CASCADES AND WA/BC BORDER MTNS INTO WED NT...WITH SOME
EARLY FOG/STRATUS THREAT. THEREAFTER MODELS DIVERGE OVER COLD FRONT
PASSAGE. THE FCST LEANS TO THE GFS...WITH BETTER CONSISTENCY AND
GEM/DGEX AGREEMENT. THE ECMWF TRENDED TO GFS. ALL THIS TRANSLATES
TO THE COLD FRONT PUSHING TO THE CASCADES THU AM AND EAST THU NT
INTO FRI AM...INCREASING PRECIP CHANCES. A THREAT FOR OROGRAPHIC
RAIN/SNOW SHOWERS CONTINUES FRIDAY BEFORE THE NEXT SYSTEM APPROACHES
LATER SATURDAY. SLIGHTLY ABOVE NORMAL TEMPERATURES WEDNESDAY TREND
CLOSER TO NORMAL BY SATURDAY. /JCOTE
&&
.AVIATION...
A WEAK RIDGE ALOFT WILL PROMOTE VFR CONDITIONS AT ALL TAF SITES
THROUGH 03Z TONIGHT...WITH LINGERING SNOW SHOWERS LOCALLY
OBSCURING MOUNTAINS IN THE IDAHO PANHANDLE AND CASCADE CREST.
THE NEXT PACIFIC STORM SYSTEM WILL SPREAD IFR CEILINGS TO THE
WESTERN REACHES OF THE REGION AFTER 04Z...SPREADING INTO THE
EASTERN TERMINALS AFT 10Z. THE INCOMING STORM SYSTEM WILL
ALSO TIGHTEN PRESSURE GRADIENTS LEADING TO INCREASING WINDS
FROM KPUW-KGEG WITH GUSTS OF 25-35KTS. THE PRECIPITATION
WILL BEGIN TO WANE FROM THE WEST AFTER 18Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 31 37 25 38 30 40 / 80 90 10 20 40 20
COEUR D`ALENE 30 38 27 39 30 40 / 50 90 20 20 50 20
PULLMAN 31 37 27 40 29 44 / 70 90 10 10 30 20
LEWISTON 35 42 31 47 32 49 / 40 90 20 10 20 20
COLVILLE 32 40 27 39 29 40 / 80 100 10 50 60 10
SANDPOINT 30 37 27 34 27 36 / 30 90 20 50 60 40
KELLOGG 29 33 28 33 29 37 / 30 100 70 20 50 30
MOSES LAKE 31 44 24 43 26 45 / 100 50 0 30 30 0
WENATCHEE 32 43 29 43 32 45 / 100 50 0 30 40 0
OMAK 31 43 22 41 29 45 / 100 80 0 70 80 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM PST SUNDAY FOR
NORTHERN PANHANDLE.
WINTER STORM WARNING FROM 4 AM SUNDAY TO 1 AM PST MONDAY FOR
CENTRAL PANHANDLE MOUNTAINS.
WINTER STORM WARNING FROM 4 AM TO 10 PM PST SUNDAY FOR COEUR
D`ALENE AREA...IDAHO PALOUSE.
WA...WINTER WEATHER ADVISORY FROM 4 AM TO 4 PM PST SUNDAY FOR
NORTHEAST MOUNTAINS...SPOKANE AREA...WASHINGTON PALOUSE.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM PST SUNDAY FOR
NORTHEAST BLUE MOUNTAINS.
WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM PST
SUNDAY FOR EAST SLOPES NORTHERN CASCADES.
WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO NOON PST
SUNDAY FOR OKANOGAN HIGHLANDS.
WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO NOON PST
SUNDAY FOR OKANOGAN VALLEY...UPPER COLUMBIA BASIN...
WATERVILLE PLATEAU.
&&
$$
000
FXUS66 KOTX 212256
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
256 PM PST SAT NOV 21 2009
.SYNOPSIS...
A STRONGER AND COLDER STORM SYSTEM WILL BRING THE POTENTIAL FOR
MODERATE TO HEAVY SNOWFALL OVER MUCH OF THE REGION TONIGHT AND
SUNDAY. A SERIES OF STORM SYSTEMS WILL CONTINUE TO PASS THROUGH
THE INLAND NORTHWEST EVERY 24 TO 36 HOURS THROUGH AT LEAST THE
MIDDLE OF NEXT WEEK.
&&
.DISCUSSION...
...LIGHT TO MODERATE SNOWFALL EXPECTED TONIGHT THROUGH SUNDAY
ACROSS THE INLAND NW...
TONIGHT THROUGH SUNDAY...AFTERNOON WATER VAPOR SHOWING A STRONG
PACIFIC STORM CHARGING TOWARD THE WASHINGTON COAST WITH A CLASSIC
BAROCLINIC LEAF SIGNATURE INDICATIVE OF THE ORGANIZED DEEPENING
SURFACE CYCLONE AND ASSOCIATED CONVEYOR BELTS. MODELS HAVE COME INTO
BETTER AGREEMENT REGARDING THE INCOMING STORM SYSTEM WHICH NOW
TRACK THE SURFACE LOW OVER THE KITTITAS VALLEY...ALONG THE I-90
CORRIDOR...BEFORE TRACKING TO THE NORTHEAST ACROSS THE NORTHERN
IDAHO PANHANDLE INTO SOUTHEASTERN BRITISH COLUMBIA. THE LOW WILL
BOTTOM OUT THIS EVENING WHILE CROSSING ONTO THE WASHINGTON COAST
JUST BELOW 990MB...THEN GRADUALLY FILL AND WEAKEN OVERNIGHT INTO
TOMORROW. THE HEAVIEST PRECIPITATION OVERNIGHT WILL FOCUS ALONG
THE CASCADES...WATERVILLE PLATEAU...OKANOGAN REGION...AS THE LOW
NEARS THE COAST TONIGHT AND INCREASING EASTERLY FLOW ENHANCES LIFT
UNDER A BLANKET OF DEEP ISENTROPIC ASCENT. AS THE LOW JUMPS THE
CASCADES AFT 12Z SUNDAY...THE PRECIPITATION SHIELD WILL BEGIN TO
SHIFT TOWARD FAR EASTERN WASHINGTON AND IDAHO. RADAR IMAGERY WILL
LIKELY ILLUSTRATE A WELL DEFINED DEFORMATION BAND ALONG THE
NORTHERN PERIPHERY OF THE LOW WHICH IS WHERE THE 6 HOUR LIQUID
AMTS WILL NEAR THREE-TENTHS OF AN INCH THEN AS THE LOW EJECTS TO
NORTHEAST MIDDAY TOMORROW...CONTINUED STRONG UPSLOPE INTO THE ID
PANHANDLE WILL RESULT IN THE SECOND CHANCE FOR MODERATE
PRECIPITATION RATES...MAINLY FOCUSING INTO THE PANHANDLE
MTNS...IDAHO PALOUSE...AND COEUR D ALENE AREA. SNOWFALL TOTALS
WILL GENERALLY RUN 2-5 INCHES IN THE VALLEYS WITH 6-10" IN THE
MOUNTAINS. WITH THE HIGHEST TOTALS ACROSS THE CENTRAL ID PANHANDLE
AS THE SECOND WAVE OF PRECIPITATION FORMS IN THE WAKE OF THE LOW.
THIS IS WHERE WINTER WEATHER WARNINGS WERE POSTED AND VALLEYS CAN
EXPECT 3-6" WITH 8-10" IN THE MOUNTAINS.
CURRENT OBSERVATIONS FROM THE EAST SLOPES...OKANOGAN HIGHLANDS...AND
WENATCHEE AREA SUGGEST TEMPERATURES HAVE WARMED INTO THE MID TO
UPPER 40`S BELOW 2000` WITH DEWPOINTS IN THE UPPER 20`S TO LOWER
30`S. CALCULATED WETBULB COOLING SUGGEST TEMPERATURES WILL REMAIN
IN THE MID TO UPPER 30`S WITH THE ONSET OF PRECIPITATION SO ALL
WINTER HIGHLIGHTS IN THE AFOREMENTIONED ZONES WERE FOCUSED MAINLY
ABOVE 2000`.
WINDS WILL BE BREEZY THROUGH THE PERIOD WITH THE HIGHEST GUSTS
EXPECTED SUNDAY AFTERNOON UNDER THE COLD ADVECTION REGIME. MODELS
CONTINUE TO HINT 850MB WINDS OF 35-50KTS DOWN THE EAST SLOPES AND
THIS WILL NEED TO BE MONITORED CLOSELY. THESE BREEZY WINDS WILL
ALSO CAUSE AREAS OF BLOWING SNOW AT TIMES BUT WITH THE SNOW BEING
OF A WETTER NATURE...EXPECT THIS WILL BE LOCALIZED. /SB
SUNDAY NIGHT THROUGH TUESDAY NIGHT...MODEL GUIDANCE IS IN GOOD
AGREEMENT THAT THE PERIOD WILL BEGIN ON A QUIETING NOTE AS
SUNDAYS UPPER LEVEL TROF SHIFTS INTO CENTRAL MONTANA. THE TROF
WILL BE SLOWLY REPLACED BY A WELL-DEFINED UPPER LEVEL RIDGE
RESULTING IN RAPID STABILIZATION OVER THE ENTIRE REGION. THUS THE
POST-FRONTAL SHOWERS OVER THE IDAHO PANHANDLE DUE TO MOIST UPSLOPE
SW FLOW WILL DECREASE RAPIDLY. MODEL CROSS SECTIONS SHOW THE
POTENTIAL INSTABILITY DECREASING FROM AROUND 550 MBS AT 00Z TO
LESS THAN 700 MBS BY 12Z. MEANWHILE RELATIVE HUMIDITY VALUES
DECREASE RAPIDLY ABOVE 700 MBS AS WELL. THIS SUGGESTS THAT MOST OF
THE POST-FRONTAL SHOWER ACTIVITY OVER THE CENTRAL PANHANDLE WILL
DECREASE AFTER 06Z WITH ONLY A FEW PERSISTENT SHOWERS .
GENERALLY DRY WEATHER WILL THEN PERSIST THROUGH MOST OF MONDAY UNTIL
ANOTHER FRONT PUSHES INTO WESTERN WASHINGTON LATE IN THE DAY.
MOISTURE ASSOCIATED WITH THIS DISTURBANCE WAS CURRENTLY LOCATED
JUST WEST OF 150W AND WAS ADEQUATELY HANDLED BY BOTH THE GFS AND
ECMWF AS OF 22Z. BOTH MODEL SOLUTIONS BRING THE PRE-FRONTAL UPPER
LEVEL RIDGE INTO NORTH IDAHO BY 00Z TUE WITH A SWIFT MOVING
SHORTWAVE TROF PASSING THROUGH THE SOUTHERN THIRD OF BC OVERNIGHT.
THIS SYSTEM SHOULD BE MUCH LESS DYNAMIC AND IMPRESSIVE THAN THE
ONE EXPECTED TONIGHT AND SUNDAY. IN FACT...THE MODELS HAVE BEEN
TRENDING TOWARD KEEPING THE PRECIPITATION FAIRLY LIGHT WITH MOST
OF IT HOLDING OVER THE NORTHERN THIRD OF THE CWA. GIVEN THE TRACK
OF THE UPPER LEVEL TROF...THE PRIMARY FLOW IN THE 850-700 MB LAYER
WILL REMAIN OUT OF THE WEST SO WITHOUT THE BENEFIT OF A STRONG
WARM FRONT OR ISENTROPIC ASCENT WE WOULD ALSO EXPECT TO SEE A FAIR
AMOUNT OF DOWNSLOPE FLOW OVER THE CASCADES. WHILE BOTH THE GFS AND
ECMWF DO HINT AT A WEAK WARM AIR ADVECTION PATTERN IN THE 850-700
MB LAYER ITS NOT NECESSARILY ENOUGH TO OVERCOME THE DOWNSLOPE
IMPACTS OF THE CASCADES. WHILE THIS SYSTEM WONT HAVE THE BENEFIT
OF STRONG DYNAMICAL FORCING IT WILL FEATURE A HIGH AMOUNT OF
MOISTURE...AS EVIDENCED BY PRECIPITABLE WATER VALUES AROUND
150-180 PERCENT OF NORMAL. THERE WILL ALSO BE PERSISTENT WEAK
ISENTROPIC ASCENT. WHATS INTERESTING IN THIS SCENARIO IS THE FRONT
LOSES MUCH OF ITS EASTWARD MOMENTUM AS YET ANOTHER SYSTEM PUSHES
INTO THE COAST BY LATE TUESDAY. THIS NEXT SYSTEM AMPLIFIES YET
ANOTHER SHORTWAVE RIDGE OVER THE AREA...WHICH ALLOWS THE MONDAY
FRONT TO SIT AND GRADUALLY WEAKEN OVER THE REGION AND SHIFT SLOWLY
SOUTH THROUGH TUESDAY . GIVEN THIS SCENARIO WE WOULD EXPECT TO SEE
A LIGHT AND RATHER PROLONGED STRATIFORM PRECIPITATION EVENT MUCH
OF WHICH WILL FALL AS SNOW. GIVEN THE WEAK FORCING WE PREFER THE
DRIER GFS AND ECMWF SOLUTIONS OVER THE RATHER WET NAM. AT THIS
POINT IT APPEARS WINTER HIGHLIGHTS WILL NOT BE NECESSARY. MOST OF
THE PRECIPITATION IS EXPECTED TO FALL NORTH OF I90. FX
WEDNESDAY TO SATURDAY...THE MEDIUM-RANGE STARTS WITH A RIDGE OVER
THE WEST...A WARM FRONT NR THE BC BORDER AND A COLD FRONT NR 130W.
THIS LEAVES PASSING MID/HIGHER CLOUDS AND A CHANCE OF RAIN AND SNOW
ACROSS THE CASCADES AND WA/BC BORDER MTNS INTO WED NT...WITH SOME
EARLY FOG/STRATUS THREAT. THEREAFTER MODELS DIVERGE OVER COLD FRONT
PASSAGE. THE FCST LEANS TO THE GFS...WITH BETTER CONSISTENCY AND
GEM/DGEX AGREEMENT. THE ECMWF TRENDED TO GFS. ALL THIS TRANSLATES
TO THE COLD FRONT PUSHING TO THE CASCADES THU AM AND EAST THU NT
INTO FRI AM...INCREASING PRECIP CHANCES. A THREAT FOR OROGRAPHIC
RAIN/SNOW SHOWERS CONTINUES FRIDAY BEFORE THE NEXT SYSTEM APPROACHES
LATER SATURDAY. SLIGHTLY ABOVE NORMAL TEMPERATURES WEDNESDAY TREND
CLOSER TO NORMAL BY SATURDAY. /JCOTE
&&
.AVIATION...
A WEAK RIDGE ALOFT WILL PROMOTE VFR CONDITIONS AT ALL TAF SITES
THROUGH 03Z TONIGHT...WITH LINGERING SNOW SHOWERS LOCALLY
OBSCURING MOUNTAINS IN THE IDAHO PANHANDLE AND CASCADE CREST.
THE NEXT PACIFIC STORM SYSTEM WILL SPREAD IFR CEILINGS TO THE
WESTERN REACHES OF THE REGION AFTER 04Z...SPREADING INTO THE
EASTERN TERMINALS AFT 10Z. THE INCOMING STORM SYSTEM WILL
ALSO TIGHTEN PRESSURE GRADIENTS LEADING TO INCREASING WINDS
FROM KPUW-KGEG WITH GUSTS OF 25-35KTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 31 37 25 38 30 40 / 80 90 10 20 40 20
COEUR D`ALENE 30 38 27 39 30 40 / 50 90 20 20 50 20
PULLMAN 31 37 27 40 29 44 / 70 90 10 10 30 20
LEWISTON 35 42 31 47 32 49 / 40 90 20 10 20 20
COLVILLE 32 40 27 39 29 40 / 80 100 10 50 60 10
SANDPOINT 30 37 27 34 27 36 / 30 90 20 50 60 40
KELLOGG 29 33 28 33 29 37 / 30 100 70 20 50 30
MOSES LAKE 31 44 24 43 26 45 / 100 50 0 30 30 0
WENATCHEE 32 43 29 43 32 45 / 100 50 0 30 40 0
OMAK 31 43 22 41 29 45 / 100 80 0 70 80 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM PST SUNDAY FOR
NORTHERN PANHANDLE.
WINTER STORM WARNING FROM 4 AM SUNDAY TO 1 AM PST MONDAY FOR
CENTRAL PANHANDLE MOUNTAINS.
WINTER STORM WARNING FROM 4 AM TO 10 PM PST SUNDAY FOR COEUR
D`ALENE AREA...IDAHO PALOUSE.
WA...WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO NOON PST
SUNDAY FOR OKANOGAN HIGHLANDS.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM PST SUNDAY FOR
NORTHEAST BLUE MOUNTAINS.
WINTER WEATHER ADVISORY FROM 4 AM TO 4 PM PST SUNDAY FOR
NORTHEAST MOUNTAINS...SPOKANE AREA...WASHINGTON PALOUSE.
WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO NOON PST
SUNDAY FOR UPPER COLUMBIA BASIN.
WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM PST
SUNDAY FOR OKANOGAN VALLEY...WATERVILLE PLATEAU...WENATCHEE
AREA.
WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM PST
SUNDAY FOR EAST SLOPES NORTHERN CASCADES.
&&
$$
000
FXUS66 KPQR 212226
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
220 PM PST SAT NOV 21 2009
.SYNOPSIS...A STRONG PACIFIC FRONTAL SYSTEM IS APPROACHING THE COAST
THIS AFTERNOON WITH A WARM FRONT MOVING INLAND THIS AFTERNOON AND
EVENING...AND THE ASSOCIATED COLD FRONT QUICKLY FOLLOWING TONIGHT AS
A SURFACE LOW PRESSURE SYSTEM MOVES INLAND NEAR THE WA OREGON BORDER.
A WEAK RIDGE OF HIGH PRESSURE WILL FOLLOW SUN AFTERNOON AND
NIGHT...BEFORE THE NEXT FRONTAL SYSTEM ARRIVES MON.
&&
.SHORT TERM...MODELS ARE STILL SHOWING DIFFERENCES IN TRACK OF THE
SURFACE LOW COMING IN TONIGHT. THE GENERAL CONSENSUS IS TO BRING IT
IN JUST NORTH OF THE WASHINGTON/OREGON BORDER. MODELS ARE IN BETTER
AGREEMENT ON THE UPPER FEATURES...WITH A STRONG SHORTWAVE MOVING
ACROSS THE FORECAST AREA TONIGHT...DIGGING TO THE ESE. TIMING OF THE
COLD FRONT IN ALL MODELS INDICATES FRONTAL PASSAGE ON THE COAST
AROUND MIDNIGHT TONIGHT. HAVE UPGRADED THE HIGH WIND WATCH FOR THE
ENTIRE COAST TO A HIGH WIND WARNING. WINDS INLAND LOOK GUSTY WITH AND
BEHIND THE FRONT AS THERE ARE STRONG PRESSURE RISES BEHIND THE
FRONT...WILL ISSUE AN ADVISORY FOR THE WILLAMETTE VALLEY..I-5
CORRIDOR AND THE LOWER COLUMBIA FOR TONIGHT AND EARLY SUNDAY MORNING
WITH THE AFTERNOON PACKAGE.
DOPPLER RADAR INDICATES THAT SHOWERS HAVE SIGNIFICANTLY DIMINISHED
OVER THE AREA WITH ONLY AN ISOLATED SHOWER OR TWO OVER THE SOUTH
WASHINGTON CASCADES AND HAVE ALREADY CANCELLED THE SNOW ADVISORY FOR
THE CASCADES. WILL CONTINUE THE WINTER STORM WARNING FOR THE
CASCADES AS MOISTURE...STRENGTH OF THE FRONT AND THE POST FRONTAL
FLOW ALL FAVOR SIGNIFICANT SNOWFALL FOR LATER TONIGHT AND SUN.
A WEAK UPPER RIDGE WILL BUILD OVER THE FORECAST AREA SUNDAY NIGHT AND
MONDAY FOLLOWING THE FRONT. BEST CHANCES FOR PRECIPITATION MONDAY AND
TUESDAY WILL SHIFT N INTO WA WITH WARM FRONT OVERRUNNING. THE UPPER
RIDGE HOLDS COLD FRONT AT BAY UNTIL AFTER TUE NIGHT. LIKENS
.LONG TERM...WEAK HIGH PRES RIDGE OVER THE FORECAST AREA CONTINUES TO
PUSH ENERGY NORTH OF FORECAST AREA MID WEEK. IT MANAGES TO DELAY THE
ARRIVAL OF A SECOND SYSTEM THROUGH THUR. MODEL SOLUTIONS DIVERGE
TOWARD THE END OF THE WEEK AND HAVE LITTLE CONFIDENCE IN THEM. AT
THIS TIME WILL GO WITH CLIMATOLOGY UNTIL THERE IS SOME CONSISTENCY
BETWEEN THE MODELS..
&&
.AVIATION...PREDOMINATELY VFR WITH SCATTERED SHOWERS...WHICH MAY
BRING VERY BRIEF MVFR CIGS. CONDITIONS REMAIN VFR THIS
AFTERNOON...THOUGH WILL SEE INCREASING MVFR ALONG THE COAST AS WARM
FRONT SWINGS ACROSS THE REGION. COLD FRONT TONIGHT WILL BRING
INCREASING MVFR AFTER 04Z...AND INCREASING SOUTHERLY WINDS SOME OF
WHICH MAY BE QUITE STRONG IN SOME AREAS. LOCATION OF STRONG WINDS
WILL DEPEND ON WHERE THE LOW COMES INLAND.
KPDX AND APPROACHES...VFR CONDITIONS THROUGH 05Z...THEN INCREASING
MVFR CIGS AS COLD FRONT APPROACHES. WATCH FOR POTENTIAL OF LOW LEVEL
WIND SHEAR BETWEEN 06Z AND 18Z TONIGHT AND TOMORROW MORNING AS WILL
SEE INCREASING SOUTH WINDS ALOFT...BLOWING OVER THE LOW LEVEL
EASTERLY FLOW COMING FROM GORGE. SOUTH TO SOUTHWEST WINDS MAY BE
QUITE STRONG AROUND 12Z AS STRONG GRADIENT DEVELOPS OVER NORTH
VALLEY AS LOW MOVES INLAND. WIND GUSTS NEAR 50 TO 55 MPH ARE
POSSIBLE. WOLFE
&&
.MARINE...GALE FORCE SOUTH WINDS WILL STRENGTHEN TO STORM FORCE AS
POTENT LOW MOVES OVER THE COASTAL WATERS. STORM WARNING FOR THE
COASTAL WATERS FOR TONIGHT. WINDS TURN MORE W TO NW ON SUNDAY AND
BEGIN EASING. SEAS TONIGHT LIKELY TO PEAK IN THE 20 TO 25 FT
RANGE...BUT WILL DROP QUICKLY TO THE MID TEENS ON SUN.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...GALE WARNING FOR COASTAL WATERS FROM CAPE SHOALWATER TO
FLORENCE FOR THIS AFTERNOON.
STORM WARNING FOR COASTAL WATERS FROM CAPE SHOALWATER TO
FLORENCE FOR TONIGHT.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR CONDITIONS
THROUGH SUN.
WINTER STORM WARNING FOR THE S WA AND N AND CENTRAL OREGON
CASCADES TONIGHT AND SUNDAY.
HIGH WIND WARNING FOR THE SOUTHERN WASHINGTON/NORTHERN AND
CENTRAL OREGON COAST TONIGHT.
WIND ADVISORY FOR THE WILLAMETTE VALLEY..THE LOWER
COLUMBIA..AND THE I-5 CORRIDOR FOR THIS EVENING THROUGH
SUNDAY MORNING.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KSEW 211915 AAA
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
1113 AM PST SAT NOV 21 2009
.SYNOPSIS...A WEAK UPPER LEVEL RIDGE WILL MOVE OVER WESTERN
WASHINGTON THROUGH MIDDAY TODAY...FOLLOWED QUICKLY BY A VIGOROUS
FRONTAL SYSTEM THIS AFTERNOON AND EVENING BRINGING RAIN AND WINDY
CONDITIONS TO THE AREA INTO SUNDAY. HEAVY SNOW WILL FALL IN THE
MOUNTAINS WITH THE SNOW LEVEL REMAINING AT OR BELOW 3000 FEET. A
WEAKER FRONT WILL MOVE THROUGH THE AREA MONDAY AND MONDAY
NIGHT...AND ANOTHER WEAK FRONT WILL ARRIVE LATER IN THE WEEK.
&&
.SHORT TERM...NORTHWEST FLOW ALOFT OVER WESTERN WASHINGTON AND
LINGERING SCATTERED SHOWERS ACROSS THE AREA THIS MORNING. THE
FREEZING LEVEL HAS FALLEN TO AROUND 3000 FT. THE WEAK OFFSHORE RIDGE
WILL CONTINUE TO MOVE QUICKLY ACROSS WESTERN WASHINGTON THIS
MORNING...FOLLOWED BY THE SOUTH END OF AN OCCLUDED FRONT SWINGING
INTO BRITISH COLUMBIA BRINGING SIGNIFICANT PRECIPITATION TO THE THE
COAST AND OLYMPICS THIS AFTERNOON. A FRONTAL WAVE AND STRONG JET
WILL 45N/145W WILL DEEPEN AND MOVE THROUGH THE FORECAST AREA
TONIGHT.
HEAVY SNOW FOR THE MOUNTAINS REMAINS ON TRACK WITH IMPRESSIVE
PRECIPITATION AMOUNTS OVER THE OLYMPICS IN THE 3 TO 4 INCH RANGE AND
THE CASCADES IN THE 1 TO 3 INCH NEIGHBORHOOD THROUGH SUNDAY MORNING.
SNOW LEVELS RISE TO AROUND 3000 FT AS THIS FEATURE MOVES THROUGH...
WITH ROUGHLY TO 30 TO 40 INCHES OF SNOW EXPECTED FOR THE OLYMPICS
AND 10 TO 30 INCHES FOR THE CASCADES. EVEN THE RELATIVELY DRIER
HURRICANE RIDGE AREA SHOULD RECEIVE WINTER STORM WARNING
AMOUNTS...IE 12 INCHES IN 12 HOURS OR 18 INCHES IN 24 HOURS.
THE TRACK OF THE SURFACE LOW REMAINS ONE OF THE FORECAST CHALANGES
FOR THE DAY. THE MOST LIKELY SCENARIO REMAINS THAT IT WILL REACH THE
CENTRAL WASHINGTON COAST AROUND MIDNIGHT TONIGHT...MOVE NORTHEAST
ACROSS THE OLYMPIC PENINSULA AND INTO THE NORTH PART OF THE PUGET
SOUND REGION TO AROUND MT BAKER AT 4 AM AND THEN HEAD INTO BRITISH
COLUMBIA. IT WILL PRODUCE BREEZY TO WINDY CONDITIONS ACROSS THE
AREA. STONGEST WINDS WILL LIKELY BE WITH THE SOUTHERLIES AHEAD OF
THE LOW TONIGHT ESPECIALLY ALONG THE COAST AND NORTHWEST
INTERIOR...AND AGAIN WITH THE WESTERLIES SUNDAY MORNING THROUGH THE
EAST STRAIT INTO WHIDBEY ISLAND. FOR NOW HAVE ISSUED A HIGH WIND
WATCH FOR THE CENTRAL WASHINGTON COAST THROUGH THE CHEHALIS GAP AND
INTO THE SOUTHWEST INTERIOR FOR THE STRONG WESTERLIES WITH THE LOW
SUNDAY MORNING. IN ADDITION HAVE ISSUED A WIND ADVISORY FOR THE
NORTH INTERIOR...ADMIRALTY INLET...SAN JUANS AND EAST STRAIT FOR THE
SOUTHERLIES THIS AFTERNOON AND TONGITH FOLLOWED BY THE WESTERLIES
WITH AND BEHIND THE LOW. WILL BE WATCHING EVOLUTION AND TRACK OF THE
LOW AS IT APPROACHES THE COAST THIS AFTERNOON. WINDS SHOULD BEGIN TO
COME DOWN BY LATE SUNDAY MORNING ALL AREAS.
POST-FRONTAL SHOWERS WILL TAPER OFF SUNDAY AFTERNOON EVENING AS AN
UPPER RIDGE WILL MOVE OVERHEAD SUNDAY EVENING. THE RIDGE KICKS EAST
QUICKLY MONDAY AHEAD OF ANOTHER FRONTAL SYSTEM. THIS SYSTEM COULD
STILL BRING DECENT PRECIPITATION AMOUNTS TO THE COAST AND OLYMPIC
PENINSULA MONDAY AFTERNOON...BUT WEAKENS AS IT MOVES INLAND MONDAY
NIGHT. COMPARED TO LAST SEVERAL SYSTEMS THIS WILL BE AN UNEVENTFUL
SYSTEM...MARKING THE BEGINNING OF A PERIOD OF QUIETER WEATHER. COOK
.LONG TERM...FROM PREVIOUS DISCUSSION...A WEAK UPPER RIDGE WILL
FOLLOW THE FRONT THAT MOVES THROUGH MONDAY AND MONDAY NIGHT. THERE
IS JUST A CHANCE OF RAIN IN THE FORECAST FOR TUESDAY AND
WEDNESDAY...WITH A FAIRLY GOOD CHANCE FOR SOME DRY WEATHER OVER
THOSE TWO DAYS. A WEAK FRONT WILL SLOWLY MOVE ACROSS WESTERN
WASHINGTON WEDNESDAY NIGHT AND THURSDAY. ANOTHER FRONTAL WAVE WILL
PROBABLY KEEP THE AREA WET THURSDAY NIGHT AND FRIDAY...THOUGH
DISAGREEMENT BETWEEN MODELS DROPS OFF CONSIDERABLY BY LATE IN THE
WEEK. MCDONNAL
&&
.HYDROLOGY...TODAYS SYSTEM WILL BRING IMPRESSIVE AMOUNTS OF
PRECIPITATION TO THE CASCADES AND OLYMPICS...BUT RELATIVELY LOW SNOW
LEVELS WILL MITIGATE THE IMPACT ON RIVERS EXCEPT THE TWO RIVERS THAT
ARE ALREADY CLOSE TO OR ABOVE FLOOD STAGE -- THE SKOKOMISH AND THE
LOWER REACH OF THE CHEHALIS IN GRAYS HARBOR COUNTY. THE SNOW LEVEL
WILL ONLY RISING TO AROUND 3000 FT...MAKING THIS MOSTLY A MOUNTAIN
SNOW EVENT AND NOT A RAIN EVENT.
THE SKOKOMISH RIVER HAS FALLEN TO NEAR OR JUST BELOW FLOOD STAGE AT
THIS TIME...NEW FORECAST GUIDANCE SHOWS THE RIVER RISING AGAIN TO
JUST BELOW 17 FEET BY EARLY SUNDAY MORNING. IN ADDITION...THERE WILL
BE A PLANNED RELEASE OF 3000 CFS FROM CUSHMAN DAM #2 INTO THE NORTH
FORK SKOKOMISH RIVER THIS AFTERNOON. ACCORDINGLY WILL EXTEND THE
WARNING FOR THE SKOKOMISH INTO MONDAY.
A FLOOD WATCH REMAINS IN EFFECT FOR THE LOWER REACH OF THE CHEHALIS
RIVER IN GRAYS HARBOR COUNTY...WHICH HAS BEEN WITHIN A FOOT OF FLOOD
STAGE FOR THE PAST TWO DAYS. IT REMAINS CONCEIVABLE THAT THE
PRECIPITATION FROM THE INCOMING SYSTEM COULD HELP FINALLY NUDGE THE
LOWER CHEHALIS ABOVE FLOOD STAGE. IF FLOODING DOES OCCUR IT WILL BE
MINOR.
THE NEXT SYSTEM ON MONDAY LOOKS TO BE PROGRESSIVE ENOUGH AND WEAK
ENOUGH TO BE OF LITTLE CONCERN WITH RESPECT TO FLOODING. THE AIR
MASS OVER THE NORTHWEST FOR THE REMAINDER OF THE WEEK WILL BE WARMER
WITH HIGHER SNOW LEVELS...HOWEVER THE SYSTEMS THAT ARE EXPECTED TO
AFFECT THE AREA WILL BE FAIRLY WEAK AND ARE NOT EXPECTED TO CAUSE
ANY ADDITIONAL FLOODING CONCERNS.
NO FLOODING IS EXPECTED AT ANY TIME ON THE GREEN RIVER. COOK
&&
.AVIATION...A WARM FRONT WILL SPREAD RAIN INTO WRN WA THIS AFTERNOON
THROUGH TONIGHT. SW FLOW ALOFT WILL INCREASE THROUGH THE DAY AND
BECOME STRONG SLY FLOW BY THIS EVENING. THE ATMOSPHERE WILL REMAIN
MOIST AND STABLE.
A STRONG SURFACE LOW WILL DEVELOP OFFSHORE TODAY AND
TONIGHT...REACHING THE S OR CENTRAL WA COAST BY 12Z SUN MORNING AS A
POTENTIAL 985 MB LOW. THIS WILL BRING STRONG SLY FLOW ALOFT AND AT
THE SURFACE...SHIFTING WLY AFTER 12Z AS THE LOW TRACKS INLAND NEAR
KHQM...PROBABLY TRACKING JUST SOUTH OF KOLM. HOWEVER...THE TRACK IS
UNCERTAIN AT THIS TIME WITH SOME MODELS SHOWING A MORE NORTHERN
SOLUTION.
KSEA...SLY WINDS 8-15 KT TODAY...BECOMING MORE ELY TONIGHT. THERE
WILL BE A POTENTIAL FOR LLWS BETWEEN 03Z AND 12Z SUN DUE TO ELY
WINDS AT THE SFC AND STRONG SLY WINDS NEAR 2K FT. CONFIDENCE IS
STILL LOW BUT MAY WILL MONITOR AND IF NEEDED UPDATE THE TAF PRIOR TO
THE 00Z ISSUANCE. LATEST 12Z MODEL SOLUTIONS CONTINUE TO VARY
CONSIDERABLE REGARDING THE TRACK AND DEPTH OF A SURFACE LOW NOW
EXPECTED TO AFFECT THE AREA. WINDS WILL INCREASE DRAMATICALLY FROM
THE SW SOMETIME BETWEEN 12Z AND 15Z. CONCERNING CIGS...ANTICIPATE
CIGS TO GRADUALLY LOWER DURING THE DAY...ALTHOUGH THERE WILL BE
OCCASIONAL CIGS NEAR 2500 FT THIS MORNING. BY LATE THIS
EVENING...CIGS SHOULD BE NEAR 2K FT...WITH RAIN AND FOG REDUCING
VSBYS INTO THE 3-5SM RANGE. DTM
&&
.MARINE...WINDS WILL PICK UP ALONG THE COAST BY MIDDAY AND ACROSS
THE INLAND WATERS DURING THE AFTERNOON AS A WARM FRONT REACHES
WESTERN WASHINGTON. LATEST MODELS SHOW GALES TO DEVELOP WITH THIS
INITIAL FRONT FROM AROUND THE E ENTRANCE/ADMIRALTY INLET NWD AND
ALSO THE COASTAL WATERS. WIND ADVISORY FOR THE SOUND STILL LOOKS
GOOD.
A POTENTIALLY STRONG 985 MB SURFACE LOW WILL ENTER THE COASTAL
WATERS AFTER 09Z TONIGHT AND TRACK INTO THE CENTRAL/S WA COAST
AROUND 12Z. WINDS BEHIND THE FRONT WILL RISE DRASTICALLY SO I UPPED
THE WINDS TO HIGH END GALE AND EXTENDED THE WARNING THROUGH SUN
MORNING. DEPENDING ON THE EXACT TRACK...STORM FORCE WINDS COULD BE
POSSIBLE ACROSS THE CENTRAL/S WA COASTAL WATERS. WILL EVALUATE THIS
POSSIBILITY BEFORE THE AFTERNOON COASTAL FORECAST ISSUANCE. DTM
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WARNINGS AND/OR FLOOD WATCHES REMAIN IN EFFECT FOR
A PORTION OF THE CWA.
A WINTER STORM WARNING IS IN EFFECT FOR THE OLYMPICS AND
CASCADES FROM THIS AFTERNOON THROUGH SUNDAY MORNING.
WIND ADVISORY IN EFFECT FOR THE NORTH INTERIOR...EAST
STRAIT...AND ADMIRALTY INLET THROUGH SUNDAY MORNING.
HIGH WIND WATCH IN EFFECT FOR THE CENTRAL COAST...LOWER
CHEHALIS...AND SOUTHWEST INTERIOR FROM LATE TONIGHT THROUGH
SUNDAY MORNING...
PZ...A GALE WARNING IS IN EFFECT FOR THE COASTAL WATERS...AND
FROM ADMIRALTY INLET NORTHWARD THROUGH EARLY SUN MORNING.
.A GALE WATCH IS IN EFFECT FOR THE CENTRAL AND
EAST STRAIT...AND ADMIRALTY INLET FROM EARLY
SUN MORNING THROUGH SUNDAY AFTERNOON.
.A SMALL CRAFT ADVISORY IS IN EFFECT FOR PUGET SOUND FROM
NOON THROUGH SUNDAY MORNING.
$$
WWW.WEATHER.GOV/SEATTLE
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.
000
FXUS66 KOTX 211810
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1010 AM PST SAT NOV 21 2009
.SYNOPSIS...
AFTER A SHORT RELATIVELY QUIET BREAK IN THE WEATHER TODAY...A
STRONGER AND COLDER STORM SYSTEM WILL BRING THE POTENTIAL FOR
MODERATE TO HEAVY SNOWFALL OVER MUCH OF THE REGION TONIGHT AND
SUNDAY. A SERIES OF STORM SYSTEMS WILL CONTINUE TO PASS THROUGH
THE INLAND NORTHWEST EVERY 24 TO 36 HOURS THROUGH AT LEAST THE
MIDDLE OF NEXT WEEK.
&&
.DISCUSSION...
QUICK UPDATE THIS MORNING TO DECREASE CLOUDS AND POPS ACROSS THE
BASIN AND NORTHERN VALLEYS. VISIBLE SATELLITE IMAGERY SHOWING
VERY LITTLE IN THE WAY OF CLOUDS AT THIS HOUR AND SHOWER ACTIVITY
IS MAINLY CONFINED TO THE HIGHER TERRAIN OF THE CASCADES AND IDAHO
PANHANDLE. WATER VAPOR IMAGERY SHOWING A FAST MOVING STORM SYSTEM
BEGINNING TO TAKE SHAPE OUT NEAR 135W 45N WHICH WILL BRING OUR
NEXT ROUND OF WINTRY WEATHER OVERNIGHT INTO SUNDAY.
&&
.AVIATION...
A WEAK RIDGE ALOFT WILL PROMOTE VFR CONDITIONS AT ALL TAF SITES
THROUGH 03Z TONIGHT...WITH LINGERING SNOW SHOWERS LOCALLY
OBSCURING MOUNTAINS IN THE IDAHO PANHANDLE AND CASCADE CREST.
THE NEXT PACIFIC STORM SYSTEM WILL SPREAD IFR CEILINGS TO THE
WESTERN REACHES OF THE REGION AFTER 04Z...SPREADING INTO THE
EASTERN TERMINALS AFT 10Z. THE INCOMING STORM SYSTEM WILL
ALSO TIGHTEN PRESSURE GRADIENTS LEADING TO INCREASING WINDS
FROM KPUW-KGEG WITH GUSTS OF 25-35KTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 39 32 37 27 39 31 / 10 70 90 10 40 10
COEUR D`ALENE 39 31 37 28 40 31 / 20 60 90 20 50 20
PULLMAN 40 32 36 28 42 32 / 20 60 90 20 40 20
LEWISTON 47 36 41 30 48 35 / 10 60 90 20 30 20
COLVILLE 39 33 40 28 38 30 / 10 100 90 10 60 20
SANDPOINT 33 32 37 28 36 30 / 40 90 90 20 60 30
KELLOGG 32 30 34 27 35 30 / 70 70 100 40 60 40
MOSES LAKE 45 32 43 26 43 30 / 10 80 50 0 40 10
WENATCHEE 43 32 43 29 41 33 / 10 90 50 10 50 10
OMAK 43 31 42 25 40 27 / 10 100 50 0 60 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID... WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
COEUR D`ALENE AREA.
WINTER STORM WATCH FROM 6 PM PST THIS EVENING THROUGH SUNDAY
MORNING FOR NORTHERN PANHANDLE.
WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY AFTERNOON
ABOVE 2500 FEET FOR CENTRAL PANHANDLE MOUNTAINS.
WA... WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
SPOKANE AREA.
WINTER STORM WATCH FROM 6 PM PST THIS EVENING THROUGH SUNDAY
MORNING FOR EAST SLOPES NORTHERN CASCADES.
WINTER STORM WATCH FROM 6 PM PST THIS EVENING THROUGH SUNDAY
MORNING ABOVE 2000 FEET FOR NORTHEAST MOUNTAINS...OKANOGAN
HIGHLANDS.
WINTER STORM WATCH FROM 6 PM PST THIS EVENING THROUGH SUNDAY
MORNING ABOVE 2000 FEET FOR OKANOGAN VALLEY...UPPER
COLUMBIA BASIN...WATERVILLE PLATEAU.
&&
$$
000
FXUS66 KPQR 211718
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
917 AM PST SAT NOV 21 2009
...UPDATED FOR HIGH WIND WATCH AND POSSIBLE WIND ADVISORY IN THE
WILLAMETTE VALLEY TONIGHT...
.SYNOPSIS...A WARM FRONT WILL APPROACH THE OREGON COAST THIS
AFTERNOON THEN PUSH INLAND THIS EVENING. A COLD FRONT WILL QUICKLY
FOLLOW TONIGHT AS A SURFACE LOW PRESSURE SYSTEM MOVES INLAND NEAR THE
WA OREGON BORDER. A WEAK RIDGE OF HIGH PRESSURE WILL FOLLOW SUN
AFTERNOON AND NIGHT...BEFORE THE NEXT FRONTAL SYSTEM ARRIVES MON.
&&
.SHORT TERM...LATEST MODEL RUNS CONTINUE TO EXHIBIT DIFFERENCES IN
TRACK OF THE SURFACE LOW COMING IN TONIGHT. UPPER FEATURES APPEAR
PRETTY WELL AGREED ON...WITH A STRONG SHORTWAVE MOVING ACROSS THE
FORECAST AREA TONIGHT...DIGGING TO THE ESE. GIVEN THE TRACT OF THE
UPPER VORT MAX AND THE NEGATIVE TILT OF THE UPPER TROUGH...CONTINUE
TO PREFER A MORE SOUTHERLY TRACK OF THE SURFACE LOW...AS SUCH PREFER
THE 00Z RUN OF THE ECMWF WHICH TAKES A SURFACE LOW E ROUGHLY ACROSS
KKLS AT 12Z SUN. TIMING OF THE COLD FRONT IN ALL MODELS INDICATES
FRONTAL PASSAGE ON THE COAST NOT UNTIL SOMETIME TONIGHT. GIVEN THE
CONTINUED UNCERTAINTIES IN THE MODELS...WILL EXTEND THE HIGH WIND
WATCH FOR THE N AND CENTRAL OREGON COAST TO INCLUDE THE SOUTHERN
WASHINGTON COAST...AND EXTEND IT TILL 6AM. WINDS INLAND LOOK GUSTY
WITH AND BEHIND THE FRONT AS THERE ARE STRONG PRESSURE RISES BEHIND
THE FRONT...EXPECT AN ADVISORY FOR SOME PORTION OF THE WILLAMETTE
VALLEY FOR LATE TONIGHT WILL BE NEEDED...WILL PROBABLY ISSUE WITH
AFTERNOON PACKAGE.
DOPPLER RADAR CONTINUES TO SHOW SHOWERS SPREADING OVER MOST OF THE
FORECAST AREA THIS MORNING AS WESTERLY FLOW ALOFT FOLLOWS THE UPPER
TROUGH. WITH UPPER RIDGING LATER TODAY...AND LOW LEVEL FLOW BACKING
MORE TO THE S...SHOULD SEE SHOWERS DROP OFF TODAY. OVERNIGHT SNOWFALL
AMOUNTS IN THE CASCADES SINCE LAST EVENING HAVE RANGED FROM ROUGHLY 4
TO 9 INCHES. FOR NOW WILL HANG ONTO THE SNOW ADVISORY FOR THE N
OREGON AND S WA CASCADES TODAY...ALTHOUGH WILL LIKELY SEE A
SIGNIFICANT DROPOFF IN SNOWFALL LATER THIS MORNING. WILL CONTINUE
THE WINTER STORM WARNING FOR THE CASCADES AS MOISTURE...STRENGTH OF
THE FRONT AND THE POST FRONTAL FLOW ALL FAVOR SIGNIFICANT SNOWFALL
LATER TONIGHT AND SUN.
CURRENT MODEL RUNS INDICATE BEST CHANCES FOR PRECIPITATION MONDAY
WILL SHIFT N INTO WA WITH WARM FRONT OVERRUNNING. THE UPPER RIDGE
HOLDS COLD FRONT AT BAY UNTIL MON NIGHT. LIKENS
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...WEAK HIGH PRES
BUILDS OVER THE FORECAST AREA MON NIGHT. MODELS SHOW A WEAK SYSTEM
APPROACH THE COAST EARLY TUE...BUT IT TRACKS FURTHER NORTH AND
LIGHTLY BRUSHES THE FAR NORTHWEST CORNER OF THE CWA. THIS RIDGE IS
MORE PERSISTENT THAN PREVIOUS MODEL RUNS SUGGESTED. IT MANAGES TO
DELAY THE ARRIVAL OF A SECOND SYSTEM THROUGH THUR. BY MID NEXT
WEEK...MODELS DISAGREE ON THE SOLUTION FOR THE WEEKEND. GFS MODEL
RUNS ARE INCONSISTENT...THE 06Z RUN HELD BACK ON PRECIP THROUGH THURS
NIGHT BUT THE CURRENT RUN SHOWS RAIN EXTENDING TO THE CASCADES THURS
NIGHT. SO FAR...MODELS SUGGEST A FAIRLY NICE WEEKEND AS ANOTHER UPPER
HIGH PRES TEMPORARILY SETS UP OVER THE PAC NW. LRAMIREZ
&&
.AVIATION...LITTLE CHANGE IN OVERALL CONDITIONS THIS MORNING.
PREDOMINATELY VFR WITH SCATTERED SHOWERS...WHICH MAY BRING VERY
BRIEF MVFR CIGS. CONDITIONS REMAIN VFR THROUGH TODAY...THOUGH WILL
SEE INCREASING MVFR ALONG THE COAST AFTER 20Z AS WARM FRONT SWINGS
ACROSS THE REGION. COLD FRONT TONIGHT WILL BRING INCREASING MVFR
AFTER 04Z...AND INCREASING SOUTHERLY WINDS.
KPDX AND APPROACHES...VFR CONDITIONS THROUGH 05Z...THEN INCREASING
MVFR CIGS AS COLD FRONT APPROACHES. WATCH FOR POTENTIAL OF LOW LEVEL
WIND SHEAR BETWEEN 00Z AND 06Z TONIGHT AS WILL SEE INCREASING SOUTH
WINDS ALOFT...BLOWING OVER THE LOW LEVEL EASTERLY FLOW COMING FROM
GORGE.ROCKEY/WOLFE
&&
.MARINE...NOT MUCH CHANGE. CONDITIONS WILL DETERIORATE LATER TODAY
AS WARM FRONT LIFTS ACROSS THE REGION. THIS WILL BRING GALE FORCE
SOUTH WINDS. HOWEVER...STRONG WINDS ARRIVE TONIGHT AS RATHER STRONG
LOW PRES PASSES ACROSS THE N OREGON COASTAL WATERS. STORM WARNING
FOR THE COASTAL WATERS FOR TONIGHT. WINDS TURN MORE W TO NW ON
SUNDAY AND BEGIN EASING. SEAS TONIGHT LIKELY TO PEAK IN THE 20 TO 25
FT RANGE...BUT WILL DROP QUICKLY ON SUN.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...GALE WARNING FOR COASTAL WATERS FROM CAPE SHOALWATER TO
FLORENCE FOR THIS AFTERNOON.
STORM WARNING FOR COASTAL WATERS FROM CAPE SHOALWATER TO
FLORENCE FOR TONIGHT.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR CONDITIONS
THROUGH SUN.
SNOW ADVISORY FOR THE SOUTH WASHINGTON AND NORTH OREGON
CASCADES THROUGH 4 PM.
WINTER STORM WARNING FOR THE S WA AND N AND CENTRAL OREGON
CASCADES TONIGHT AND SUNDAY.
HIGH WIND WATCH FOR THE SOUTHERN WASHINGTON/NORTHERN AND
CENTRAL OREGON COAST TONIGHT.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KPQR 211634
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
833 AM PST SAT NOV 21 2009
.SYNOPSIS...A WARM FRONT WILL APPROACH THE OREGON COAST THIS
AFTERNOON THEN PUSH INLAND THIS EVENING. A COLD FRONT WILL QUICKLY
FOLLOW TONIGHT AS A SURFACE LOW PRESSURE SYSTEM MOVES INLAND NEAR THE
WA OREGON BORDER. A WEAK RIDGE OF HIGH PRESSURE WILL FOLLOW SUN
AFTERNOON AND NIGHT...BEFORE THE NEXT FRONTAL SYSTEM ARRIVES MON.
&&
.SHORT TERM...LATEST MODEL RUNS CONTINUE TO EXHIBIT DIFFERENCES IN
TRACK OF THE SURFACE LOW COMING IN TONIGHT. UPPER FEATURES APPEAR
PRETTY WELL AGREED ON...WITH A STRONG SHORTWAVE MOVING ACROSS THE
FORECAST AREA TONIGHT...DIGGING TO THE ESE. GIVEN THE TRACT OF THE
UPPER VORT MAX AND THE NEGATIVE TILT OF THE UPPER TROUGH...CONTINUE
TO PREFER A MORE SOUTHERLY TRACK OF THE SURFACE LOW...AS SUCH PREFER
THE 00Z RUN OF THE ECMWF WHICH TAKES A SURFACE LOW E ROUGHLY ACROSS
KKLS AT 12Z SUN. TIMING OF THE COLD FRONT IN ALL MODELS INDICATES
FRONTAL PASSAGE ON THE COAST NOT UNTIL SOMETIME TONIGHT. GIVEN THE
CONTINUED UNCERTAINTIES IN THE MODELS...FOR NOW WILL LEAVE HEADLINE
AS A HIGH WIND WATCH FOR THE N AND CENTRAL OREGON COAST...BUT LIMIT
IT TO TONIGHT PERIOD. WINDS INLAND LOOK GUSTY WITH AND BEHIND THE
FRONT AS THERE ARE STRONG PRESSURE RISES BEHIND THE FRONT. AT THIS
TIME THOUGH...BEST GUESS IS FOR WINDS TO BE BELOW WARNING
CRITERIA...ALTHOUGH WILLAMETTE VALLEY MAY APPROACH ADVISORY LEVELS
LATE TONIGHT.
DOPPLER RADAR CONTINUES TO SHOW SHOWERS SPREADING OVER MOST OF THE
FORECAST AREA THIS MORNING AS WESTERLY FLOW ALOFT FOLLOWS THE UPPER
TROUGH. WITH UPPER RIDGING LATER TODAY...AND LOW LEVEL FLOW BACKING
MORE TO THE S...SHOULD SEE SHOWERS DROP OFF TODAY. OVERNIGHT SNOWFALL
AMOUNTS IN THE CASCADES SINCE LAST EVENING HAVE RANGED FROM ROUGHLY 4
TO 9 INCHES. FOR NOW WILL HANG ONTO THE SNOW ADVISORY FOR THE N
OREGON AND S WA CASCADES TODAY...ALTHOUGH WILL LIKELY SEE A
SIGNIFICANT DROPOFF IN SNOWFALL LATER THIS MORNING. WILL CONTINUE
THE WINTER STORM WARNING FOR THE CASCADES AS MOISTURE...STRENGTH OF
THE FRONT AND THE POST FRONTAL FLOW ALL FAVOR SIGNIFICANT SNOWFALL
LATER TONIGHT AND SUN.
CURRENT MODEL RUNS INDICATE BEST CHANCES FOR PRECIPITATION MONDAY
WILL SHIFT N INTO WA WITH WARM FRONT OVERRUNNING. THE UPPER RIDGE
HOLDS COLD FRONT AT BAY UNTIL MON NIGHT. LIKENS
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...WEAK HIGH PRES
BUILDS OVER THE FORECAST AREA MON NIGHT. MODELS SHOW A WEAK SYSTEM
APPROACH THE COAST EARLY TUE...BUT IT TRACKS FURTHER NORTH AND
LIGHTLY BRUSHES THE FAR NORTHWEST CORNER OF THE CWA. THIS RIDGE IS
MORE PERSISTENT THAN PREVIOUS MODEL RUNS SUGGESTED. IT MANAGES TO
DELAY THE ARRIVAL OF A SECOND SYSTEM THROUGH THUR. BY MID NEXT
WEEK...MODELS DISAGREE ON THE SOLUTION FOR THE WEEKEND. GFS MODEL
RUNS ARE INCONSISTENT...THE 06Z RUN HELD BACK ON PRECIP THROUGH THURS
NIGHT BUT THE CURRENT RUN SHOWS RAIN EXTENDING TO THE CASCADES THURS
NIGHT. SO FAR...MODELS SUGGEST A FAIRLY NICE WEEKEND AS ANOTHER UPPER
HIGH PRES TEMPORARILY SETS UP OVER THE PAC NW. LRAMIREZ
&&
.AVIATION...LITTLE CHANGE IN OVERALL CONDITIONS THIS MORNING.
PREDOMINATELY VFR WITH SCATTERED SHOWERS...WHICH MAY BRING VERY
BRIEF MVFR CIGS. CONDITIONS REMAIN VFR THROUGH TODAY...THOUGH WILL
SEE INCREASING MVFR ALONG THE COAST AFTER 20Z AS WARM FRONT SWINGS
ACROSS THE REGION. COLD FRONT TONIGHT WILL BRING INCREASING MVFR
AFTER 04Z...AND INCREASING SOUTHERLY WINDS.
KPDX AND APPROACHES...VFR CONDITIONS THROUGH 05Z...THEN INCREASING
MVFR CIGS AS COLD FRONT APPROACHES. WATCH FOR POTENTIAL OF LOW LEVEL
WIND SHEAR BETWEEN 00Z AND 06Z TONIGHT AS WILL SEE INCREASING SOUTH
WINDS ALOFT...BLOWING OVER THE LOW LEVEL EASTERLY FLOW COMING FROM
GORGE.ROCKEY/WOLFE
&&
.MARINE...NOT MUCH CHANGE. CONDITIONS WILL DETERIORATE LATER TODAY
AS WARM FRONT LIFTS ACROSS THE REGION. THIS WILL BRING GALE FORCE
SOUTH WINDS. HOWEVER...STRONG WINDS ARRIVE TONIGHT AS RATHER STRONG
LOW PRES PASSES ACROSS THE N OREGON COASTAL WATERS. STORM WARNING
FOR THE COASTAL WATERS FOR TONIGHT. WINDS TURN MORE W TO NW ON
SUNDAY AND BEGIN EASING. SEAS TONIGHT LIKELY TO PEAK IN THE 20 TO 25
FT RANGE...BUT WILL DROP QUICKLY ON SUN.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...GALE WARNING FOR COASTAL WATERS FROM CAPE SHOALWATER TO
FLORENCE FOR THIS AFTERNOON.
STORM WARNING FOR COASTAL WATERS FROM CAPE SHOALWATER TO
FLORENCE FOR TONIGHT.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR CONDITIONS
THROUGH SUN.
SNOW ADVISORY FOR THE SOUTH WASHINGTON AND NORTH OREGON
CASCADES THROUGH 4 PM.
WINTER STORM WARNING FOR THE S WA AND N AND CENTRAL OREGON
CASCADES TONIGHT AND SUNDAY.
HIGH WIND WATCH FOR THE NORTHERN AND CENTRAL OREGON COAST
TONIGHT.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KSEW 211233 AAA
AFDSEW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SEATTLE WA
433 AM PST SAT NOV 21 2009
UPDATED THE AVIATION AND MARINE SEGMENTS.
.SYNOPSIS...A WEAK RIDGE WILL MOVE THROUGH WESTERN WASHINGTON THIS
MORNING...FOLLOWED QUICKLY BY A VIGOROUS FRONTAL SYSTEM. THIS SYSTEM
WILL BRING RAIN AND WINDY CONDITIONS TONIGHT AND SUNDAY. HEAVY SNOW
WILL FALL IN THE MOUNTAINS WITH THE SNOW LEVEL REMAINING AT OR BELOW
3000 FEET. A WEAKER FRONT WILL MOVE THROUGH THE AREA MONDAY AND
MONDAY NIGHT...AND ANOTHER WEAK FRONT WILL ARRIVE LATE IN THE WEEK.
&&
.SHORT TERM...WE HAVE NORTHWEST FLOW ALOFT OVER WESTERN WASHINGTON
BETWEEN AN UPPER TROUGH THAT MOVED THROUGH THE AREA OVERNIGHT AND A
WEAK UPPER RIDGE OFFSHORE ALONG 130W. THERE ARE STILL SCATTERED
SHOWERS ACROSS THE FORECAST AREA THIS MORNING...AND A PUGET SOUND
CONVERGENCE ZONE EXTENDING ACROSS ISLAND AND SNOHOMISH COUNTIES. IT
IS STILL BREEZY IN SOME AREAS...BUT THE WIND SHOULD EASE OVER THE
NEXT FEW HOURS AS THE SURFACE HIGH PRESSURE THAT HAS BEEN BUILDING
INTO THE AREA SHIFTS EAST OF THE CASCADES AHEAD OF THE NEXT FRONT.
THE FREEZING LEVEL HAS FALLEN TO AROUND 3000 FT AND TEMPERATURES
ACROSS THE WESTERN WASHINGTON LOWLANDS WERE IN THE UPPER 30S TO MID
40S AT 3 AM.
THE WEAK RIDGE OFFSHORE WILL MOVE QUICKLY ACROSS WESTERN WASHINGTON
THIS MORNING...AND THE CONVERGENCE ZONE WILL LIKELY WEAKEN AND
DISSIPATE. THE SOUTH END OF AN OCCLUDED FRONT SWINGING INTO BRITISH
COLUMBIA WILL QUICKLY FOLLOW THE RIDGE...WITH SIGNIFICANT
PRECIPITATION REACHING THE COAST AND OLYMPICS THIS AFTERNOON. A
FRONTAL WAVE BEGINNING TO DEVELOP NEAR 45N/145W WILL DEEPEN AS IT
MOVES RAPIDLY EASTWARD WITH THE HELP OF A 140 KT JET. IT WILL MOVE
THROUGH THE FORECAST AREA TONIGHT.
HEAVY SNOW IN THE MOUNTAINS LOOKS LIKE A SURE BET. THE SNOW LEVEL
WILL RISE ONLY TO AROUND 3000 FT AS THIS FEATURE MOVES THROUGH...AND
PRECIPITATION AMOUNTS WILL BE IMPRESSIVE. LIQUID AMOUNTS OF 3 TO 4
INCHES IN THE OLYMPICS ARE POSSIBLE THROUGH SUNDAY MORNING --
TRANSLATING ROUGHLY TO 30 TO 40 INCHES OF SNOW. EVEN THE RELATIVELY
DRIER HURRICANE RIDGE AREA SHOULD RECEIVE WINTER STORM WARNING
AMOUNTS...IE 12 INCHES IN 12 HOURS OR 18 INCHES IN 24 HOURS. WATER
EQUIVALENTS IN THE CASCADES WILL LIKELY BE IN THE 1 TO 3 INCH
RANGE...FOR SNOWFALL TOTALS OF 10 INCHES TO 2.5 FT. THE WINTER STORM
WATCH WILL BE UPGRADED TO A WARNING WITH THE EARLY MORNING FORECAST
PACKAGE.
ONE MATTER THAT IS SOMEWHAT UNCERTAIN IS THE TRACK OF THE SURFACE
LOW. THE MOST LIKELY SCENARIO IS THAT IT WILL REACH THE CENTRAL
WASHINGTON COAST AROUND MIDNIGHT TONIGHT...TRACK NORTHEAST ACROSS
THE OLYMPIC PENINSULA AND THE NORTH PART OF THE PUGET SOUND REGION
TO AROUND MT BAKER AT 4 AM...THEN HEAD RAPIDLY INTO BRITISH
COLUMBIA. IT WILL PRODUCE BREEZY TO WINDY CONDITIONS...BUT THERE
APPEARS TO BE LITTLE THREAT OF A WIND STORM.
POST-FRONTAL SHOWERS WILL TAPER OFF SUNDAY AFTERNOON AND EVENING...
AND AN UPPER RIDGE WILL MOVE INLAND SUNDAY NIGHT. THE RIDGE WILL
QUICKLY HEAD EAST OF THE CASCADES MONDAY AND ANOTHER FRONTAL SYSTEM
JUST UPSTREAM OF THE RIDGE WILL ARRIVE. THIS SYSTEM COULD INITIALLY
BRING DECENT PRECIPITATION AMOUNTS TO THE COAST AND OLYMPIC
PENINSULA MONDAY AFTERNOON...BUT IT WILL WEAKEN AS IT MOVES INLAND
MONDAY NIGHT. BY RECENT STANDARDS THIS WILL BE AN UNEVENTFUL SYSTEM
AND IT WILL MARK THE BEGINNING OF A PERIOD OF QUIETER...THOUGH NOT
NECESSARILY DRY...WEATHER. MCDONNAL
.LONG TERM...A WEAK UPPER RIDGE WILL FOLLOW THE FRONT THAT MOVES
THROUGH MONDAY AND MONDAY NIGHT. THERE IS JUST A CHANCE OF RAIN IN
THE FORECAST FOR TUESDAY AND WEDNESDAY...WITH A FAIRLY GOOD CHANCE
FOR SOME DRY WEATHER OVER THOSE TWO DAYS. A WEAK FRONT WILL SLOWLY
MOVE ACROSS WESTERN WASHINGTON WEDNESDAY NIGHT AND THURSDAY. ANOTHER
FRONTAL WAVE WILL PROBABLY KEEP THE AREA WET THURSDAY NIGHT AND
FRIDAY...THOUGH DISAGREEMENT BETWEEN MODELS DROPS OFF CONSIDERABLY
BY LATE IN THE WEEK. MCDONNAL
&&
.HYDROLOGY...THE SYSTEM COMING IN TODAY THROUGH MIDDAY SUNDAY ...
WHILE IT WILL PRODUCE IMPRESSIVE AMOUNTS OF PRECIPITATION...WILL
HAVE MINIMAL EFFECT ON RIVERS EXCEPT POSSIBLY FOR THE TWO RIVERS
THAT ARE ALREADY CLOSE TO OR ABOVE FLOOD STAGE -- THE SKOKOMISH AND
THE LOWER REACH OF THE CHEHALIS IN GRAYS HARBOR COUNTY. WITH THE
SNOW LEVEL ONLY RISING TO AROUND 3000 FT...IT WILL BE A MOUNTAIN
SNOW PRODUCER NOT A FLOODING RAIN PRODUCER.
THE SKOKOMISH RIVER IS FORECAST TO FALL BELOW FLOOD STAGE ABOUT NOON
TODAY. THERE WILL BE A PLANNED RELEASE OF 3000 CFS FROM CUSHMAN DAM
#2 INTO THE NORTH FORK SKOKOMISH RIVER TODAY. THIS RELEASE WILL KEEP
THE SKOKOMISH RIVER RUNNING HIGH. THE FORECAST CALLS FOR THE RIVER
TO REMAIN JUST BELOW FLOOD STAGE TONIGHT AND SUNDAY.
A FLOOD WATCH REMAINS IN EFFECT FOR THE LOWER REACH OF THE CHEHALIS
RIVER IN GRAYS HARBOR COUNTY...WHICH HAS BEEN WITHIN A FOOT OF FLOOD
STAGE FOR THE PAST TWO DAYS. IT IS CONCEIVABLE THAT THE
PRECIPITATION FROM THE INCOMING SYSTEM COULD HELP FINALLY NUDGE THE
LOWER CHEHALIS ABOVE FLOOD STAGE. IF FLOODING DOES OCCUR IT WILL BE
MINOR.
THE NEXT SYSTEM ON MONDAY SHOULD MOVE THROUGH QUICKLY AND BE TOO
WEAK TO CAUSE ANY FLOODING...EVEN WITH RISING SNOW LEVELS. FOR THE
REMAINDER OF THE WEEK...THE AIR MASS OVER THE NORTHWEST WILL BE
WARMER WITH HIGHER SNOW LEVELS...HOWEVER THE SYSTEMS THAT ARE
EXPECTED TO AFFECT THE AREA WILL BE FAIRLY WEAK AND ARE NOT EXPECTED
TO CAUSE ANY ADDITIONAL FLOODING CONCERNS.
NO FLOODING IS EXPECTED AT ANY TIME ON THE GREEN RIVER. MCDONNAL
&&
.AVIATION...A WEAK...UPPER RIDGE OVER THE REGION WILL MOVE E
TONIGHT...ALLOWING A STRONG...UPPER TROF TO MOVE OVER THE AREA.
INCREASING WLY FLOW ALOFT...SUBSIDING AND BECOMING NW LATE TONIGHT.
AT THE SFC...A FRONTAL SYSTEM OVER THE ERN PAC WILL RAPIDLY APPROACH
WRN WA DURING THE DAY TODAY...RESULTING IN INCREASED SLY WINDS. THE
OCCLUDED FRONT WILL MOVE ACROSS THE AREA THIS EVENING. A SECONDARY
SFC LOW IS ANTICIPATED TO DEVELOP OFF THE FAR SW WA OR FAR NW OREGON
COAST THIS EVENING...AND TRACK NEWD ACROSS THE AREA LATER TONIGHT.
THUS EXPECT THE WINDS TO BACK BEHIND THE OCCLUDED FRONT THIS
EVENING...AND THIS SHOULD RAISE THE POTENTIAL FOR LLWS SINCE WINDS
ABOVE THE SFC WILL REMAIN SLY. WINDS WILL PICK UP DRAMATICALLY FROM
THE W OR SW LATE TONIGHT OR EARLY SUNDAY ONCE THE SFC LOW MOVES E OF
THE AREA.
MEANWHILE...A PUGET SOUND CONVERGENCE ZONE /PSCZ/ WAS ROUGHLY
LOCATED BETWEEN KPAE AND KAWO AT THIS TIME. THIS FEATURE SHOULD
DRIFT N AND DISSIPATE BY MIDMORNING AS ITS SUPPORT WANES.
KSEA...WINDS WILL REMAIN SLY TODAY...BECOMING MORE ELY TONIGHT.
THERE WILL BE A POTENTIAL FOR LLWS BETWEEN 0000 AND 1200 UTC SUNDAY
DUE TO ELY WINDS AT THE SFC AND STRONG SLY WINDS NEAR 2K FT. HAVE
HELD OFF ON MENTIONING THIS IN THE TAF TIL WE SEE ANOTHER MODEL RUN.
THE CURRENT MODEL SOLUTIONS WERE QUITE DIFFERENT THAN THE PREVIOUS
RUN DUE TO A MORE VIGOROUS SYSTEM NOW EXPECTED TO AFFECT THE AREA.
WINDS WILL INCREASE DRAMATICALLY FROM THE SW SOMETIME BETWEEN 1000
UTC AND 1200 UTC SUNDAY. CONCERNING CIGS...ANTICIPATE CIGS TO
GRADUALLY LOWER DURING THE DAY...ALTHOUGH THERE WILL BE OCCASIONAL
CIGS NEAR 2500 FT THIS MORNING. BY LATE THIS EVENING...CIGS SHOULD
BE NEAR 2K FT...WITH RAIN AND FOG REDUCING VSBYS INTO THE 3-5SM
RANGE.
&&
.MARINE...THERE WAS A SIGNIFICANT CHANGE IN THE FORECAST FROM THE
PREVIOUS ONE DUE TO A MORE VIGOROUS SYSTEM EXPECTED TO AFFECT THE
AREA TODAY. SLY WINDS ARE STILL ANTICIPATED TO INCREASE DURING THE
DAY...AHEAD OF A FAST-MOVING FRONTAL SYSTEM STILL WELL OFFSHORE...
FOR GALE OR SMALL CRAFT ADVISORY WIND SPEEDS. THE OCCLUDED FRONT
WILL SWEEP ACROSS THE AREA THIS EVENING. DUE TO SOMEWHAT LOW
CONFIDENCE HAVE WENT WITH A SMALL CRAFT ADVISORY FOR THE NORTHERN
INLAND WATERS AND EAST ENTRANCE TO THE STRAIT OF JUAN DE FUCA TODAY
INSTEAD OF UPGRADING THE PREVIOUS GALE WATCH TO A WARNING.
ANOTHER SURFACE WAVE OR LOW IS EXPECTED TO DEVELOP OFF THE FAR SW
WASHINGTON OR FAR NW OREGON COAST TONIGHT...AND THIS WILL CAUSE THE
WINDS TO BACK AND DROP OFF...ESPECIALLY ACROSS THE INLAND WATERS.
THE LOW WILL MOVE NE ACROSS INTERIOR WESTERN WASHINGTON OVERNIGHT.
WINDS WILL KICK BACK UP LATE TONIGHT OR EARLY SUNDAY IN RESPONSE TO
STRONG ONSHORE OR WESTERLY FLOW DEVELOPING. CONFIDENCE WAS FAIRLY
HIGH THAT GALE FORCE WINDS WILL DEVELOP OVER THE STRAIT OF JUAN DE
FUCA EARLY SUNDAY...THUS HAVE ISSUED A GALE WATCH FOR THE CENTRAL
AND EASTERN STRAIT. THERE IS A POSSIBILITY THAT WINDS MAY BRIEFLY
REACH STORM FORCE...NEAR 50 KNOTS...OVER THE CENTRAL STRAIT SUNDAY
MORNING WITH THE INITIAL PUSH.
ANTICIPATE THE ONSHORE FLOW TO WEAKEN AND BECOME SOUTHERLY SUNDAY
NIGHT. THE NEXT FRONTAL SYSTEM WILL AFFECT THE WATERS ON MON.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WARNINGS AND/OR FLOOD WATCHES REMAIN IN EFFECT FOR A
PORTION OF THE CWA.
A WINTER STORM WARNING IS IN EFFECT FOR THE OLYMPICS AND
CASCADES FROM THIS AFTERNOON THROUGH SUNDAY MORNING.
PZ...A GALE WARNING REMAINS IN EFFECT FOR THE COASTAL WATERS AND
WEST ENTRANCE TO THE STRAIT OF JUAN DE FUCA THROUGH THIS
EVENING.
A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE REMAINING
WATERS.
A SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR CONDITIONS
IS IN EFFECT TIL NOON MON.
$$
WWW.WEATHER.GOV/SEATTLE
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.
000
FXUS66 KSEW 211212
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 AM PDT SAT NOV 21 2009
.SYNOPSIS...A WEAK RIDGE WILL MOVE THROUGH WESTERN WASHINGTON THIS
MORNING...FOLLOWED QUICKLY BY A VIGOROUS FRONTAL SYSTEM. THIS SYSTEM
WILL BRING RAIN AND WINDY CONDITIONS TONIGHT AND SUNDAY. HEAVY SNOW
WILL FALL IN THE MOUNTAINS WITH THE SNOW LEVEL REMAINING AT OR BELOW
3000 FEET. A WEAKER FRONT WILL MOVE THROUGH THE AREA MONDAY AND
MONDAY NIGHT...AND ANOTHER WEAK FRONT WILL ARRIVE LATE IN THE WEEK.
&&
.SHORT TERM...WE HAVE NORTHWEST FLOW ALOFT OVER WESTERN WASHINGTON
BETWEEN AN UPPER TROUGH THAT MOVED THROUGH THE AREA OVERNIGHT AND A
WEAK UPPER RIDGE OFFSHORE ALONG 130W. THERE ARE STILL SCATTERED
SHOWERS ACROSS THE FORECAST AREA THIS MORNING...AND A PUGET SOUND
CONVERGENCE ZONE EXTENDING ACROSS ISLAND AND SNOHOMISH COUNTIES. IT
IS STILL BREEZY IN SOME AREAS...BUT THE WIND SHOULD EASE OVER THE
NEXT FEW HOURS AS THE SURFACE HIGH PRESSURE THAT HAS BEEN BUILDING
INTO THE AREA SHIFTS EAST OF THE CASCADES AHEAD OF THE NEXT FRONT.
THE FREEZING LEVEL HAS FALLEN TO AROUND 3000 FT AND TEMPERATURES
ACROSS THE WESTERN WASHINGTON LOWLANDS WERE IN THE UPPER 30S TO MID
40S AT 3 AM.
THE WEAK RIDGE OFFSHORE WILL MOVE QUICKLY ACROSS WESTERN WASHINGTON
THIS MORNING...AND THE CONVERGENCE ZONE WILL LIKELY WEAKEN AND
DISSIPATE. THE SOUTH END OF AN OCCLUDED FRONT SWINGING INTO BRITISH
COLUMBIA WILL QUICKLY FOLLOW THE RIDGE...WITH SIGNIFICANT
PRECIPITATION REACHING THE COAST AND OLYMPICS THIS AFTERNOON. A
FRONTAL WAVE BEGINNING TO DEVELOP NEAR 45N/145W WILL DEEPEN AS IT
MOVES RAPIDLY EASTWARD WITH THE HELP OF A 140 KT JET. IT WILL MOVE
THROUGH THE FORECAST AREA TONIGHT.
HEAVY SNOW IN THE MOUNTAINS LOOKS LIKE A SURE BET. THE SNOW LEVEL
WILL RISE ONLY TO AROUND 3000 FT AS THIS FEATURE MOVES THROUGH...AND
PRECIPITATION AMOUNTS WILL BE IMPRESSIVE. LIQUID AMOUNTS OF 3 TO 4
INCHES IN THE OLYMPICS ARE POSSIBLE THROUGH SUNDAY MORNING --
TRANSLATING ROUGHLY TO 30 TO 40 INCHES OF SNOW. EVEN THE RELATIVELY
DRIER HURRICANE RIDGE AREA SHOULD RECEIVE WINTER STORM WARNING
AMOUNTS...IE 12 INCHES IN 12 HOURS OR 18 INCHES IN 24 HOURS. WATER
EQUIVALENTS IN THE CASCADES WILL LIKELY BE IN THE 1 TO 3 INCH
RANGE...FOR SNOWFALL TOTALS OF 10 INCHES TO 2.5 FT. THE WINTER STORM
WATCH WILL BE UPGRADED TO A WARNING WITH THE EARLY MORNING FORECAST
PACKAGE.
ONE MATTER THAT IS SOMEWHAT UNCERTAIN IS THE TRACK OF THE SURFACE
LOW. THE MOST LIKELY SCENARIO IS THAT IT WILL REACH THE CENTRAL
WASHINGTON COAST AROUND MIDNIGHT TONIGHT...TRACK NORTHEAST ACROSS
THE OLYMPIC PENINSULA AND THE NORTH PART OF THE PUGET SOUND REGION
TO AROUND MT BAKER AT 4 AM...THEN HEAD RAPIDLY INTO BRITISH
COLUMBIA. IT WILL PRODUCE BREEZY TO WINDY CONDITIONS...BUT THERE
APPEARS TO BE LITTLE THREAT OF A WIND STORM.
POST-FRONTAL SHOWERS WILL TAPER OFF SUNDAY AFTERNOON AND EVENING...
AND AN UPPER RIDGE WILL MOVE INLAND SUNDAY NIGHT. THE RIDGE WILL
QUICKLY HEAD EAST OF THE CASCADES MONDAY AND ANOTHER FRONTAL SYSTEM
JUST UPSTREAM OF THE RIDGE WILL ARRIVE. THIS SYSTEM COULD INITIALLY
BRING DECENT PRECIPITATION AMOUNTS TO THE COAST AND OLYMPIC
PENINSULA MONDAY AFTERNOON...BUT IT WILL WEAKEN AS IT MOVES INLAND
MONDAY NIGHT. BY RECENT STANDARDS THIS WILL BE AN UNEVENTFUL SYSTEM
AND IT WILL MARK THE BEGINNING OF A PERIOD OF QUIETER...THOUGH NOT
NECESSARILY DRY...WEATHER. MCDONNAL
.LONG TERM...A WEAK UPPER RIDGE WILL FOLLOW THE FRONT THAT MOVES
THROUGH MONDAY AND MONDAY NIGHT. THERE IS JUST A CHANCE OF RAIN IN
THE FORECAST FOR TUESDAY AND WEDNESDAY...WITH A FAIRLY GOOD CHANCE
FOR SOME DRY WEATHER OVER THOSE TWO DAYS. A WEAK FRONT WILL SLOWLY
MOVE ACROSS WESTERN WASHINGTON WEDNESDAY NIGHT AND THURSDAY. ANOTHER
FRONTAL WAVE WILL PROBABLY KEEP THE AREA WET THURSDAY NIGHT AND
FRIDAY...THOUGH DISAGREEMENT BETWEEN MODELS DROPS OFF CONSIDERABLY
BY LATE IN THE WEEK. MCDONNAL
&&
.HYDROLOGY...THE SYSTEM COMING IN TODAY THROUGH MIDDAY SUNDAY ...
WHILE IT WILL PRODUCE IMPRESSIVE AMOUNTS OF PRECIPITATION...WILL
HAVE MINIMAL EFFECT ON RIVERS EXCEPT POSSIBLY FOR THE TWO RIVERS
THAT ARE ALREADY CLOSE TO OR ABOVE FLOOD STAGE -- THE SKOKOMISH AND
THE LOWER REACH OF THE CHEHALIS IN GRAYS HARBOR COUNTY. WITH THE
SNOW LEVEL ONLY RISING TO AROUND 3000 FT...IT WILL BE A MOUNTAIN
SNOW PRODUCER NOT A FLOODING RAIN PRODUCER.
THE SKOKOMISH RIVER IS FORECAST TO FALL BELOW FLOOD STAGE ABOUT NOON
TODAY. THERE WILL BE A PLANNED RELEASE OF 3000 CFS FROM CUSHMAN DAM
#2 INTO THE NORTH FORK SKOKOMISH RIVER TODAY. THIS RELEASE WILL KEEP
THE SKOKOMISH RIVER RUNNING HIGH. THE FORECAST CALLS FOR THE RIVER
TO REMAIN JUST BELOW FLOOD STAGE TONIGHT AND SUNDAY.
A FLOOD WATCH REMAINS IN EFFECT FOR THE LOWER REACH OF THE CHEHALIS
RIVER IN GRAYS HARBOR COUNTY...WHICH HAS BEEN WITHIN A FOOT OF FLOOD
STAGE FOR THE PAST TWO DAYS. IT IS CONCEIVABLE THAT THE
PRECIPITATION FROM THE INCOMING SYSTEM COULD HELP FINALLY NUDGE THE
LOWER CHEHALIS ABOVE FLOOD STAGE. IF FLOODING DOES OCCUR IT WILL BE
MINOR.
THE NEXT SYSTEM ON MONDAY SHOULD MOVE THROUGH QUICKLY AND BE TOO
WEAK TO CAUSE ANY FLOODING...EVEN WITH RISING SNOW LEVELS. FOR THE
REMAINDER OF THE WEEK...THE AIR MASS OVER THE NORTHWEST WILL BE
WARMER WITH HIGHER SNOW LEVELS...HOWEVER THE SYSTEMS THAT ARE
EXPECTED TO AFFECT THE AREA WILL BE FAIRLY WEAK AND ARE NOT EXPECTED
TO CAUSE ANY ADDITIONAL FLOODING CONCERNS.
NO FLOODING IS EXPECTED AT ANY TIME ON THE GREEN RIVER. MCDONNAL
&&
.AVIATION...DELAYED.
&&
.MARINE...A STRONG FRONTAL SYSTEM WILL APPROACH THE AREA TODAY...
RESULTING IN INCREASED SOUTHERLY FLOW. THE OCCLUDED FRONT WILL THEN
MOVE ACROSS THE AREA THIS EVENING. STRONG ONSHORE OR WESTERLY FLOW
WILL DEVELOP ON SUNDAY IN THE WAKE OF THIS FRONT. EXPECT THE NEXT
FRONTAL SYSTEM TO AFFECT THE WATERS ON MON.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WARNINGS AND/OR FLOOD WATCHES REMAIN IN EFFECT FOR A
PORTION OF THE CWA.
A WINTER STORM WARNING IS IN EFFECT FOR THE OLYMPICS AND
CASCADES FROM THIS AFTERNOON THROUGH SUNDAY MORNING.
PZ...A GALE WARNING REMAINS IN EFFECT FOR THE COASTAL WATERS AND
WEST ENTRANCE TO THE STRAIT OF JUAN DE FUCA THROUGH THIS
EVENING.
A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE REMAINING
WATERS.
A SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR CONDITIONS
IS IN EFFECT TIL NOON MON.
$$
WWW.WEATHER.GOV/SEATTLE
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.
000
FXUS66 KOTX 211132
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
330 AM PST SAT NOV 21 2009
.SYNOPSIS...
AFTER A SHORT RELATIVELY QUIET BREAK IN THE WEATHER TODAY...A
STRONGER AND COLDER STORM SYSTEM WILL BRING THE POTENTIAL FOR
MODERATE TO HEAVY SNOWFALL OVER MUCH OF THE REGION TONIGHT AND
SUNDAY. A SERIES OF STORM SYSTEMS WILL CONTINUE TO PASS THROUGH
THE INLAND NORTHWEST EVERY 24 TO 36 HOURS THROUGH AT LEAST THE
MIDDLE OF NEXT WEEK.
&&
.DISCUSSION...
TODAY...WHILE THIS MORNING`S SATELLITE LOOP LOOKS MESSY...IN GENERAL
THE FORECAST AREA IS CURRENTLY UNDER AN INTER TROUGH COLD POOL
ALOFT WHICH WILL EXIT THE REGION AND ALLOW A DIRTY AND WEAK SHORT
WAVE RIDGE TO SET UP OVER THE REGION FOR THIS AFTERNOON. IN THE
WAKE OF LAST EVENINGS COLD FRONT PASSAGE BREEZY WINDS WILL
CONTINUE THROUGH THE MORNING AS A COOLER AIR MASS FILLS THE BASIN.
THERE WILL LIKELY BE SOME RESIDUAL SNOW SHOWERS MAINLY
CONCENTRATED OVER THE IDAHO PANHANDLE MOUNTAINS AND NEAR THE
CASCADE CREST...WITH PLENTY OF CLOUDS AND A SMALL CHANCE OF A
STRAY VALLEY RAIN OR SNOW SHOWER POSSIBLE OVER THE RISING TERRAIN
OF THE EASTERN BASIN TODAY AS A MOIST WESTERLY FLOW ALOFT
CONTINUES. HIGH TEMPERATURES TODAY WILL HAVE TROUBLE BREAKING OUT
OF THE UPPER THIRTIES AT MOST LOCATIONS OTHER THAN THE LOWEST
VALLEYS.
TONIGHT THROUGH SUNDAY...A VERY TRICKY FORECAST FOR THE NEXT 24 TO
36 HOURS. THE NEXT STORM SYSTEM...VISIBLE ON PACIFIC SATELLITE AS
A DEVELOPING BAROCLINIC LEAF STRUCTURE APPROACHING 140W THIS
MORNING...WILL MOVE ASHORE SOMETIME THIS EVENING AND CROSS THE
FORECAST AREA OVERNIGHT AND INTO SUNDAY MORNING. THERE ARE SOME
SIGNIFICANT MODEL DIFFERENCES WITH THE TRACK OF THE DEVELOPING SURFACE
LOW AND THE STRENGTH OF THE PARENT TROUGH. ALL THE MODELS DEVELOP
A STRONG SURFACE LOW JUST OFF THE COAST THIS AFTERNOON AND EJECT
IT INLAND TONIGHT. THE GFS AND CANADIAN MODELS TRACK THE LOW
THROUGH THE CENTRAL CASCADES AND SWING IT NORTH INTO BRITISH
COLUMBIA...WHILE THE ECMWF AND NAM GUIDANCE TRACK THE LOW THROUGH
THE SOUTHERN COLUMBIA BASIN. THIS LOW TRACK IS CRITICAL FOR SNOW
AMOUNT POTENTIAL. ALTHOUGH ALL MODELS INDICATE SIGNIFICANT
ACCUMULATING SNOW IS LIKELY OVERNIGHT SATURDAY AND SUNDAY
MORNING...A MORE SOUTHERLY TRACK WILL BRING HEAVIER SNOW AMOUNTS
TO THE VALLEYS AND BASIN. THUS CONFIDENCE IS HIGH THAT MOST OF THE
FORECAST AREA NORTH OF INTERSTATE 90 WILL EXPERIENCE AT LEAST A
COUPLE INCHES OF SNOW TONIGHT AND SUNDAY MORNING...WITH MODERATE
TO HEAVY ACCUMULATIONS IN THE MOUNTAINS. CONFIDENCE IS LOW AT
THIS TIME WHICH MODEL WILL VERIFY BEST...AND THUS UNCERTAINTY
REMAINS ABOUT THE POTENTIAL FOR HIGHLIGHTS WITH THIS SYSTEM. THUS
A SLEW OF WATCHES HAVE BEEN ISSUED...AND HOPEFULLY FURTHER MODEL
RUNS TODAY WILL SETTLE ON A CONFIDENT SOLUTION. AT THIS TIME WE
HAVE OPTED FOR A TRACK THAT IS SLIGHTLY SOUTH OF THE GFS/CANADIAN
MODELS AND DELAYED THE TIMING CLOSER TO THE EC/NAM GIVEN THE
SATELLITE EXTRAPOLATION AND AGGRESSIVE DIGGING OF THE PARENT
TROUGH. THIS ARGUES FOR AN ONSET OF LIGHT TO MODERATE SNOW IN THE
WESTERN ZONES THIS EVENING...INTENSIFYING OVERNIGHT THEN CUTTING
OUT/TAPERING OFF WITH THE COLD FRONT PASSAGE SUNDAY MORNING. ONSET
OVER THE EAST AND NORTHERN ZONES WILL HOLD OFF UNTIL LATE
OVERNIGHT SATURDAY OR EARLY SUNDAY MORNING...REACH MAXIMUM
INTENSITY SUNDAY MORNING AND TAPER OFF SUNDAY AFTERNOON WITH THE
USUAL LINGERING DENSE SNOW SHOWERS OVER THE IDAHO PANHANDLE. /FUGAZZI
SUNDAY NIGHT THROUGH FRIDAY...THE WEEKEND STORM SYSTEM CONTINUES
ITS EXIT TO THE EAST SUNDAY NIGHT ALLOWING FOR THE HIGHER POPS
ASSOCIATED WITH IT TO SHOW A SIMILAR EXIT OUT TO THE EAST SUNDAY
NIGHT AS WEAK RIDGING MOVES THROUGH BEHIND IT. THIS RIDGING IS NOT
WELL AMPLIFIED AND APPEARS PRONE TO OVERTOPPING BY TWO STORM
SYSTEMS. THE FIRST STORM SYSTEM DRAGS A WELL MAINTAINED MOISTURE
TAPS THROUGH EASTERN WASHINGTON AND NORTHERN IDAHO MONDAY NIGHT
INTO TUESDAY WHICH DEFLATES THE WEAK RIDGING FURTHER. THIS ALLOW
THE SECOND STORM SYSTEM TO EXERT SOME INFLUENCE AS EARLY AS LATE
IN THE DAY TUESDAY...HOWEVER THE RIDGE APPEARS TO SLOWLY AMPLIFY
AS A FEW SHORTWAVES START TO DIG ON THE WEST SIDE/NORTHS SIDE OF
THE JET OF THE LARGE BAROCLINIC BAND/MOISTURE TAP ASSOCIATED WITH
THIS SECOND SYSTEM. THE RESULT IS A POSSIBLY SHUNTING OF ANY
PRECIP BAN FRONTAL FEATURE BACK UP TO THE NORTH AND WEST FROM
TUESDAY NIGHT TO AS LATE AS THANKSGIVING. EVENTUALLY A DIGGING
SHORTWAVE GETS ENOUGH SIGNIFICANT CYCLOGENESIS GOING ON THE
BAROCLINIC BAND OFFSHORE TO GET IT WRAPPED UP INTO A COMPACT LOW
THAT DUMBBELLS AROUND WITH ANOTHER LOW TO ITS NORTH AS IT MOVES
INLAND SOMETIME BETWEEN THE PERIOD BETWEEN THANKSGIVING AND
FRIDAY. /PELATTI
&&
.AVIATION...
BREEZY CONDITIONS IN THE WAKE OF A COLD FRONT PASSAGE LAST NIGHT
WILL KEEP GENERALLY VFR VISIBILITIES AT ALL TAF SITES THIS
MORNING...WITH SOME OCCASIONAL MVFR AND IFR STRATUS CEILINGS AT
KGEG/KSFF AND KCOE UNTIL 16Z. A WEAK RIDGE ALOFT WILL PROMOTE VFR
CONDITIONS AT ALL TAF SITES THROUGH 03Z TONIGHT...WITH LINGERING
SNOW SHOWERS LOCALLY OBSCURING MOUNTAINS IN THE IDAHO PANHANDLE. THE
NEXT PACIFIC STORM SYSTEM WILL SPREAD MVFR AND LOCAL IFR CIELINGS TO
THE WESTERN REACHES OF THE REGION AFTER 03Z TONIGHT...MAINLY
IMPACTING THE KEAT AND KMWH TAF SITES. CONDITIONS AT EASTERN TAF
SITES WILL BEGIN TO DETERIORATE BY THE END OF THE TAF PERIOD AT 12Z
SUNDAY.
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 39 32 37 27 39 31 / 20 70 90 10 40 10
COEUR D`ALENE 39 31 37 28 40 31 / 20 60 90 20 50 20
PULLMAN 40 32 36 28 42 32 / 20 60 90 20 40 20
LEWISTON 47 36 41 30 48 35 / 10 60 90 20 30 20
COLVILLE 39 33 40 28 38 30 / 30 100 90 10 60 20
SANDPOINT 33 32 37 28 36 30 / 40 90 90 20 60 30
KELLOGG 32 30 34 27 35 30 / 70 70 100 40 60 40
MOSES LAKE 45 32 43 26 43 30 / 10 80 50 0 40 10
WENATCHEE 43 32 43 29 41 33 / 30 90 50 10 50 10
OMAK 43 31 42 25 40 27 / 40 100 50 0 60 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID... WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
COEUR D`ALENE AREA.
WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY MORNING FOR
NORTHERN PANHANDLE.
WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY AFTERNOON
ABOVE 2500 FEET FOR CENTRAL PANHANDLE MOUNTAINS.
WA... WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
SPOKANE AREA.
WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY MORNING FOR
EAST SLOPES NORTHERN CASCADES.
WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY MORNING
ABOVE 2000 FEET FOR NORTHEAST MOUNTAINS...OKANOGAN
HIGHLANDS.
WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY MORNING
ABOVE 2000 FEET FOR OKANOGAN VALLEY...UPPER COLUMBIA
BASIN...WATERVILLE PLATEAU.
&&
$$
000
FXUS66 KOTX 211040
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
240 AM PST SAT NOV 21 2009
.SYNOPSIS...
AFTER A SHORT RELATIVELY QUIET BREAK IN THE WEATHER TODAY...A
STRONGER AND COLDER STORM SYSTEM WILL BRING THE POTENTIAL FOR
MODERATE TO HEAVY SNOWFALL OVER MUCH OF THE REGION TONIGHT AND
SUNDAY. A SERIES OF STORM SYSTEMS WILL CONTINUE TO PASS THROUGH
THE INLAND NORTHWEST EVERY 24 TO 36 HOURS THROUGH AT LEAST THE
MIDDLE OF NEXT WEEK.
&&
.DISCUSSION...
TODAY...WHILE THIS MORNING`S SATELLITE LOOP LOOKS MESSY...IN GENERAL
THE FORECAST AREA IS CURRENTLY UNDER AN INTER TROUGH COLD POOL
ALOFT WHICH WILL EXIT THE REGION AND ALLOW A DIRTY AND WEAK SHORT
WAVE RIDGE TO SET UP OVER THE REGION FOR THIS AFTERNOON. IN THE
WAKE OF LAST EVENINGS COLD FRONT PASSAGE BREEZY WINDS WILL
CONTINUE THROUGH THE MORNING AS A COOLER AIR MASS FILLS THE BASIN.
THERE WILL LIKELY BE SOME RESIDUAL SNOW SHOWERS MAINLY
CONCENTRATED OVER THE IDAHO PANHANDLE MOUNTAINS AND NEAR THE
CASCADE CREST...WITH PLENTY OF CLOUDS AND A SMALL CHANCE OF A
STRAY VALLEY RAIN OR SNOW SHOWER POSSIBLE OVER THE RISING TERRAIN
OF THE EASTERN BASIN TODAY AS A MOIST WESTERLY FLOW ALOFT
CONTINUES. HIGH TEMPERATURES TODAY WILL HAVE TROUBLE BREAKING OUT
OF THE UPPER THIRTIES AT MOST LOCATIONS OTHER THAN THE LOWEST
VALLEYS.
TONIGHT THROUGH SUNDAY...A VERY TRICKY FORECAST FOR THE NEXT 24 TO
36 HOURS. THE NEXT STORM SYSTEM...VISIBLE ON PACIFIC SATELLITE AS
A DEVELOPING BAROCLINIC LEAF STRUCTURE APPROACHING 140W THIS
MORNING...WILL MOVE ASHORE SOMETIME THIS EVENING AND CROSS THE
FORECAST AREA OVERNIGHT AND INTO SUNDAY MORNING. THERE ARE SOME
SIGNIFICANT MODEL DIFFERENCES WITH THE TRACK OF THE DEVELOPING SURFACE
LOW AND THE STRENGTH OF THE PARENT TROUGH. ALL THE MODELS DEVELOP
A STRONG SURFACE LOW JUST OFF THE COAST THIS AFTERNOON AND EJECT
IT INLAND TONIGHT. THE GFS AND CANADIAN MODELS TRACK THE LOW
THROUGH THE CENTRAL CASCADES AND SWING IT NORTH INTO BRITISH
COLUMBIA...WHILE THE ECMWF AND NAM GUIDANCE TRACK THE LOW THROUGH
THE SOUTHERN COLUMBIA BASIN. THIS LOW TRACK IS CRITICAL FOR SNOW
AMOUNT POTENTIAL. ALTHOUGH ALL MODELS INDICATE SIGNIFICANT
ACCUMULATING SNOW IS LIKELY OVERNIGHT SATURDAY AND SUNDAY
MORNING...A MORE SOUTHERLY TRACK WILL BRING HEAVIER SNOW AMOUNTS
TO THE VALLEYS AND BASIN. THUS CONFIDENCE IS HIGH THAT MOST OF THE
FORECAST AREA NORTH OF INTERSTATE 90 WILL EXPERIENCE AT LEAST A
COUPLE INCHES OF SNOW TONIGHT AND SUNDAY MORNING...WITH MODERATE
TO HEAVY ACCUMULATIONS IN THE MOUNTAINS. CONFIDENCE IS LOW AT
THIS TIME WHICH MODEL WILL VERIFY BEST...AND THUS UNCERTAINTY
REMAINS ABOUT THE POTENTIAL FOR HIGHLIGHTS WITH THIS SYSTEM. THUS
A SLEW OF WATCHES HAVE BEEN ISSUED...AND HOPEFULLY FURTHER MODEL
RUNS TODAY WILL SETTLE ON A CONFIDENT SOLUTION. AT THIS TIME WE
HAVE OPTED FOR A TRACK THAT IS SLIGHTLY SOUTH OF THE GFS/CANADIAN
MODELS AND DELAYED THE TIMING CLOSER TO THE EC/NAM GIVEN THE
SATELLITE EXTRAPOLATION AND AGGRESSIVE DIGGING OF THE PARENT
TROUGH. THIS ARGUES FOR AN ONSET OF LIGHT TO MODERATE SNOW IN THE
WESTERN ZONES THIS EVENING...INTENSIFYING OVERNIGHT THEN CUTTING
OUT/TAPERING OFF WITH THE COLD FRONT PASSAGE SUNDAY MORNING. ONSET
OVER THE EAST AND NORTHERN ZONES WILL HOLD OFF UNTIL LATE
OVERNIGHT SATURDAY OR EARLY SUNDAY MORNING...REACH MAXIMUM
INTENSITY SUNDAY MORNING AND TAPER OFF SUNDAY AFTERNOON WITH THE
USUAL LINGERING DENSE SNOW SHOWERS OVER THE IDAHO PANHANDLE. /FUGAZZI
SUNDAY NIGHT THROUGH FRIDAY...THE WEEKEND STORM SYSTEM CONTINUES
ITS EXIT TO THE EAST SUNDAY NIGHT ALLOWING FOR THE HIGHER POPS
ASSOCIATED WITH IT TO SHOW A SIMILAR EXIT OUT TO THE EAST SUNDAY
NIGHT AS WEAK RIDGING MOVES THROUGH BEHIND IT. THIS RIDGING IS NOT
WELL AMPLIFIED AND APPEARS PRONE TO OVERTOPPING BY TWO STORM
SYSTEMS. THE FIRST STORM SYSTEM DRAGS A WELL MAINTAINED MOISTURE
TAPS THROUGH EASTERN WASHINGTON AND NORTHERN IDAHO MONDAY NIGHT
INTO TUESDAY WHICH DEFLATES THE WEAK RIDGING FURTHER. THIS ALLOW
THE SECOND STORM SYSTEM TO EXERT SOME INFLUENCE AS EARLY AS LATE
IN THE DAY TUESDAY...HOWEVER THE RIDGE APPEARS TO SLOWLY AMPLIFY
AS A FEW SHORTWAVES START TO DIG ON THE WEST SIDE/NORTHS SIDE OF
THE JET OF THE LARGE BAROCLINIC BAND/MOISTURE TAP ASSOCIATED WITH
THIS SECOND SYSTEM. THE RESULT IS A POSSIBLY SHUNTING OF ANY
PRECIP BAN FRONTAL FEATURE BACK UP TO THE NORTH AND WEST FROM
TUESDAY NIGHT TO AS LATE AS THANKSGIVING. EVENTUALLY A DIGGING
SHORTWAVE GETS ENOUGH SIGNIFICANT CYCLOGENESIS GOING ON THE
BAROCLINIC BAND OFFSHORE TO GET IT WRAPPED UP INTO A COMPACT LOW
THAT DUMBBELLS AROUND WITH ANOTHER LOW TO ITS NORTH AS IT MOVES
INLAND SOMETIME BETWEEN THE PERIOD BETWEEN THANKSGIVING AND
FRIDAY. /PELATTI
&&
.AVIATION...
AREAS OF MVFR AND IFR CIGS WILL OCCUR THROUGH 18Z DUE TO ABUNDANT
LOW LEVEL MOISTURE ACROSS EASTERN WA/N IDAHO. IN THE LEE OF THE
CASCADES VFR CONDITIONS WILL PERSIST AT KEAT/KMWH AS DOWNSLOPE
FLOW HAS DRIED OUT THE LOWER LEVELS. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 39 32 37 27 39 31 / 20 70 90 10 40 10
COEUR D`ALENE 39 31 37 28 40 31 / 20 60 90 20 50 20
PULLMAN 40 32 36 28 42 32 / 20 60 90 20 40 20
LEWISTON 47 36 41 30 48 35 / 10 60 90 20 30 20
COLVILLE 39 33 40 28 38 30 / 30 100 90 10 60 20
SANDPOINT 33 32 37 28 36 30 / 40 90 90 20 60 30
KELLOGG 32 30 34 27 35 30 / 70 70 100 40 60 40
MOSES LAKE 45 32 43 26 43 30 / 10 80 50 0 40 10
WENATCHEE 43 32 43 29 41 33 / 30 90 50 10 50 10
OMAK 43 31 42 25 40 27 / 40 100 50 0 60 10
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID... WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
COEUR D`ALENE AREA.
WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY MORNING FOR
NORTHERN PANHANDLE.
WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY AFTERNOON
ABOVE 2500 FEET FOR CENTRAL PANHANDLE MOUNTAINS.
WA... WINTER STORM WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR
SPOKANE AREA.
WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY MORNING FOR
EAST SLOPES NORTHERN CASCADES.
WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY MORNING
ABOVE 2000 FEET FOR NORTHEAST MOUNTAINS...OKANOGAN
HIGHLANDS.
WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY MORNING
ABOVE 2000 FEET FOR OKANOGAN VALLEY...UPPER COLUMBIA
BASIN...WATERVILLE PLATEAU.
&&
$$
000
FXUS66 KPQR 211019
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
220 AM PST SAT NOV 21 2009
.SYNOPSIS...A WARM FRONT WILL APPROACH THE OREGON COAST THIS
AFTERNOON THEN PUSH INLAND THIS EVENING. A COLD FRONT WILL QUICKLY
FOLLOW TONIGHT AS A SURFACE LOW PRESSURE SYSTEM MOVES INLAND NEAR
THE WA OREGON BORDER. A WEAK RIDGE OF HIGH PRESSURE WILL FOLLOW SUN
AFTERNOON AND NIGHT...BEFORE THE NEXT FRONTAL SYSTEM ARRIVES MON.
&&
.SHORT TERM...LATEST MODEL RUNS CONTINUE TO EXHIBIT DIFFERENCES IN
TRACK OF THE SURFACE LOW COMING IN TONIGHT. UPPER FEATURES APPEAR
PRETTY WELL AGREED ON...WITH A STRONG SHORTWAVE MOVING ACROSS THE
FORECAST AREA TONIGHT...DIGGING TO THE ESE. GIVEN THE TRACT OF THE
UPPER VORT MAX AND THE NEGATIVE TILT OF THE UPPER TROUGH...CONTINUE
TO PREFER A MORE SOUTHERLY TRACK OF THE SURFACE LOW...AS SUCH PREFER
THE 00Z RUN OF THE ECMWF WHICH TAKES A SURFACE LOW E ROUGHLY ACROSS
KKLS AT 12Z SUN. TIMING OF THE COLD FRONT IN ALL MODELS INDICATES
FRONTAL PASSAGE ON THE COAST NOT UNTIL SOMETIME TONIGHT. GIVEN THE
CONTINUED UNCERTAINIES IN THE MODELS...FOR NOW WILL LEAVE HEADLINE
AS A HIGH WIND WATCH FOR THE N AND CENTRAL OREGON COAST...BUT LIMIT
IT TO TONIGHT PERIOD. WINDS INLAND LOOK GUSTY WITH AND BEHIND THE
FRONT AS THERE ARE STRONG PRESSURE RISES BEHIND THE FRONT. AT THIS
TIME THOUGH...BEST GUESS IS FOR WINDS TO BE BELOW WARNING
CRITERIA...ALTHOUGH WILLAMETTE VALLEY MAY APPROACH ADVISORY LEVELS
LATE TONIGHT.
SHOWERS CONTINUE OVER MOST OF THE FORECAST AREA EARLY THIS MORNING
AS A WESTERLY FLOW ALOFT FOLLOWS THE UPPER TROUGH. WITH UPPER
RIDGING LATER TODAY...AND LOW LEVEL FLOW BACKING MORE TO THE
S...SHOULD SEE SHOWERS DROP OFF TODAY. OVERNIGHT SNOWFALL AMOUNTS IN
THE CASCADES SINCE LAST EVENING HAVE RANGED FROM ROUGHLY 4 TO 9
INCHES. FOR NOW WILL HANG ONTO THE SNOW ADVISORY FOR THE N OREGON
AND S WA CASCADES TODAY...ALTHOUGH WILL LIKELY SEE A SIGNIFICANT
DROPOFF IN SNOWFALL LATER THIS MORNING. WILL UPGRADE THE WATCH
TONIGHT TO A WARNING FOR THE CASCADES AS MOISTURE...STRENGTH OF THE
FRONT AND THE POST FRONTAL FLOW ALL FAVOR SIGNIFICANT SNOWFALL LATER
TONIGHT AND SUN.
WILL BACK OFF ON POPS FOR SUN NIGHT AND MON AS CURRENT MODEL RUNS
INDICATE BEST CHANCES FOR PRECIPITATION WILL SHIFT N INTO WA WITH
BEST WARM FRONT OVERRUNNING...AND THE UPPER RIDGE HOLDS COLD FRONT
AT BAY UNTIL MON NIGHT.
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
WEAK HIGH PRES BUILDS OVER THE FORECAST AREA MON NIGHT. MODELS SHOW
A WEAK SYSTEM APPROACH THE COAST EARLY TUE...BUT IT TRACKS FURTHER
NORTH AND LIGHTLY BRUSHES THE FAR NORTHWEST CORNER OF THE CWA. THIS
RIDGE IS MORE PERSISTENT THAN PREVIOUS MODEL RUNS SUGGESTED. IT
MANAGES TO DELAY THE ARRIVAL OF A SECOND SYSTEM THROUGH THUR. BY MID
NEXT WEEK...MODELS DISAGREE ON THE SOLUTION FOR THE WEEKEND. GFS
MODEL RUNS ARE INCONSISTENT...THE 06Z RUN HELD BACK ON PRECIP
THROUGH THURS NIGHT BUT THE CURRENT RUN SHOWS RAIN EXTENDING TO THE
CASCADES THURS NIGHT. SO FAR...MODELS SUGGEST A FAIRLY NICE WEEKEND
AS ANOTHER UPPER HIGH PRES TEMPORARILY SETS UP OVER THE PAC NW.
LRAMIREZ
&&
.AVIATION...LITTLE CHANGE IN OVERALL CONDITIONS THIS MORNING.
PREDOMINATELY VFR WITH SCATTERED SHOWERS...WHICH MAY BRING VERY
BRIEF MVFR CIGS. CONDITIONS REMAIN VFR THROUGH TODAY...THOUGH WILL
SEE INCREASING MVFR ALONG THE COAST AFTER 20Z AS WARM FRONT SWINGS
ACROSS THE REGION. COLD FRONT TONIGHT WILL BRING INCREASING MVFR
AFTER 04Z...AND INCREASING SOUTHERLY WINDS.
KPDX AND APPROACHES...VFR CONDITIONS THROUGH 05Z...THEN INCREASING
MVFR CIGS AS COLD FRONT APPROACHES. WATCH FOR POTENTIAL OF LOW LEVEL
WIND SHEAR BETWEEN 00Z AND 06Z TONIGHT AS WILL SEE INCREASING SOUTH
WINDS ALOFT...BLOWING OVER THE LOW LEVEL EASTERLY FLOW COMING FROM
GORGE. ROCKEY.
&&
.MARINE...NOT MUCH CHANGE. CONDITIONS WILL DETERIORATE LATER TODAY
AS WARM FRONT LIFTS ACROSS THE REGION. THIS WILL BRING GALE FORCE
SOUTH WINDS. HOWEVER...STRONG WINDS ARRIVE TONIGHT AS RATHER STRONG
LOW PRES PASSES ACROSS THE N OREGON COASTAL WATERS. WILL HOIST STORM
WARNING FOR THE COASTAL WATERS FOR TONIGHT. WINDS TURN MORE W TO NW
ON SUNDAY AND BEGIN EASING. SEAS TONIGHT LIKELY TO PEAK IN THE 20 TO
25 FT RANGE...BUT WILL DROP QUICKLY ON SUN.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...GALE WARNING FOR COASTAL WATERS FROM CAPE SHOALWATER TO
FLORENCE FOR THIS AFTERNOON.
STORM WARNING FOR COASTAL WATERS FROM CAPE SHOALWATER TO
FLORENCE FOR TONIGHT.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBAR BAR CONDITIONS
THROUGH SUN.
SNOW ADVISORY FOR THE SOUTH WASHINGTON AND NORTH OREGON
CASCADES THROUGH 4 PM.
WINTER STORM WARNING FOR THE S WA AND N AND CENTRAL OREGON
CASCADES TONIGHT AND SUNDAY.
HIGH WIND WATCH FOR THE NORTHERN AND CENTRAL OREGON COAST
TONIGHT.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KOTX 210643
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1043 PM PST FRI NOV 20 2009
.SYNOPSIS...
AFTER A SHORT BREAK IN THE WEATHER ON SATURDAY...A STRONGER AND
COLDER STORM SYSTEM WILL BRING THE POTENTIAL FOR MODERATE TO HEAVY
SNOWFALL MAINLY IN THE HIGH VALLEYS AND MOUNTAINS. A SERIES OF STORM
SYSTEMS WILL CONTINUE TO PASS THROUGH THE INLAND NORTHWEST EVERY
24 TO 36 HOURS WELL INTO NEXT WEEK.
&&
.DISCUSSION...
A STRONG PACIFIC SYSTEM IS EXPECTED TO IMPACT THE INLAND NORTHWEST
SATURDAY NIGHT INTO SUNDAY MORNING AND WINTER STORM WATCHES HAVE
BEEN POSTED FOR PARTS OF THE AREA. THERE CONTINUES TO BE
DISAGREEMENT FROM MODEL TO MODEL REGARDING THE TRACK AND STRENGTH
OF A SFC LOW AS IT PASSES ACROSS WASHINGTON. THE 00Z GFS MODEL IS
THE STRONGEST AND TRACKS THE LOW ALONG THE WA/BC BORDER...WHILE
THE NAM IS SLOWER AND TRACKS THE LOW FROM PORTLAND TOWARDS
PULLMAN. THE NEW 00Z CANADIAN SUPPORTS THE GFS...WHILE THE 00Z
ECMWF HAS NOT YET COME IN BUT PREVIOUS ECMWF SUPPORTED THE NAM.
DOING A MODEL INITIALIZATION OF THIS SYSTEM...THE GFS INITIALIZED
A LITTLE BIT DEEPER COMPARED TO THE 12 HR FCST FROM THE 12Z ECMWF
WHICH WAS SUPPORTED BY SHIP OBSERVATIONS. WATER VAPOR ALSO SHOWS
SOME DARKENING WITH THIS SYSTEM WITH THE LEFT EXIT PORTION OF A
JET STREAK AIDING IN INTENSIFICATION. BASED ON SATELLITE TRENDS
AND THAT THE CANADIAN BACKS UP THE GFS AND WITH THE GFS APPEARING
TO HAVE A GOOD INITIALIZATION...LEANED TOWARDS THE GFS. THE GFS
SHOWS DEEP MOISTURE AND LIFT AS A 992-995MB SFC LOW TRACKS
THROUGH THE AREA WITH QPF AMOUNTS OVER AN INCH ALONG THE CASCADE
CREST AND OVER A HALF INCH OVER THE NORTHERN HALF OF EASTERN WA/N
IDAHO. THIS LOOKS TO FALL MOSTLY IN A 12 HOUR PERIOD WITH THE BULK
OF THE PRECIPITATION FALLING SATURDAY NIGHT IN THE CASCADES AND
OVERNIGHT SATURDAY INTO SUNDAY MORNING OVER EASTERN WA/N IDAHO.
TRICKY PART IS SNOW LEVELS WITH 1000-850MB THICKNESSES 1305-1310
DM...AND 850MB TEMPS OF -2 TO -3 SNOW LEVELS LOOK TO BE NEAR 2000
FEET. THUS THE WINTER STORM WATCHES HAVE BEEN ISSUED ABOVE THIS
ELEVATION. SNOW LEVELS COULD END UP A LITTLE HIGHER AT TIMES OVER
THE SPOKANE/COEUR D`ALENE AREA AS WELL AS THE PALOUSE WITH
SOUTHERLY LOW LEVEL WINDS DEVELOPING AS THE LOW TRACKS NORTH OF
THE AREA. THUS WITH LOWER CONFIDENCE IN THESE AREAS HELD OFF ON
ANY POTENTIAL WATCHES.
FOR TONIGHT DRIER AIR WILL CONTINUE TO MOVE INTO EASTERN
WASHINGTON BEHIND THE EARLIER COLD FRONT PASSAGE...WHILE UPSLOPE
POST FRONTAL SNOW SHOWERS FALL IN THE MOUNTAINS OF N IDAHO.
ACCUMULATIONS IN THE MOUNTAINS HOWEVER WILL ONLY RANGE FROM 1 TO 3
INCHES. JW
&&
.AVIATION...
AREAS OF MVFR AND IFR CIGS WILL OCCUR THROUGH 18Z DUE TO ABUNDANT
LOW LEVEL MOISTURE ACROSS EASTERN WA/N IDAHO. IN THE LEE OF THE
CASCADES VFR CONDITIONS WILL PERSIST AT KEAT/KMWH AS DOWNSLOPE
FLOW HAS DRIED OUT THE LOWER LEVELS. JW
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 33 39 32 37 27 39 / 20 20 90 80 10 40
COEUR D`ALENE 33 39 31 37 28 40 / 40 20 80 70 20 50
PULLMAN 32 39 32 36 28 42 / 50 20 70 80 20 40
LEWISTON 36 47 36 41 30 48 / 40 10 40 90 20 30
COLVILLE 32 40 33 40 28 38 / 10 30 80 70 10 60
SANDPOINT 32 36 32 37 28 36 / 90 40 80 80 20 60
KELLOGG 32 33 30 34 27 35 / 90 70 90 90 40 60
MOSES LAKE 31 45 32 43 26 43 / 0 10 80 60 0 40
WENATCHEE 32 43 32 43 29 41 / 0 30 90 50 10 50
OMAK 28 43 31 42 25 40 / 10 60 90 60 0 60
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON ABOVE 2500 FEET FOR CENTRAL PANHANDLE MOUNTAINS.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY MORNING
FOR NORTHERN PANHANDLE.
WA...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY MORNING
FOR EAST SLOPES NORTHERN CASCADES.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY MORNING
ABOVE 2000 FEET FOR NORTHEAST MOUNTAINS...OKANOGAN
HIGHLANDS.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY MORNING
ABOVE 2000 FEET FOR OKANOGAN VALLEY...WATERVILLE PLATEAU.
&&
$$
000
FXUS66 KSEW 210515
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
915 PM PST FRI NOV 20 2009
.SYNOPSIS...A TROUGH WILL MOVE THROUGH WESTERN WASHINGTON THIS
EVENING. A DEVELOPING SURFACE LOW IN THE EAST CENTRAL PACIFIC WILL
MOVE ACROSS SOUTHERN PORTIONS OF WASHINGTON SUNDAY NIGHT. A FRONTAL
SYSTEM WILL MOVE THROUGH THE AREA MONDAY OR MONDAY NIGHT. YET
ANOTHER FRONT WILL MOVE ACROSS THE AREA MIDWEEK.
&&
.SHORT TERM...A RATHER STRONG ZONAL FLOW CONTINUES ACROSS THE
PACIFIC THIS EVENING. BUT THE PATTERN ACROSS NORTH AMERICA IS
INCREASINGLY SPLIT. SO WHILE INCOMING SYSTEMS OVER THE NEXT SEVERAL
DAYS WILL NOT LIKELY BE AS STRONG OR AS WET AS SYSTEMS THAT IMPACTED
THE AREA DURING THE LAST WEEK...THE TIMING AND PLACEMENT OF SYSTEMS
WILL BE INCREASINGLY DIFFICULT FOR NUMERICAL MODELS TO HANDLE AS
TIME MOVES FORWARD.
THIS EVENING A COLD UPPER TROUGH IS MOVING ACROSS THE AREA WITH 500
MB TEMPERATURES AROUND -33C AND 850 MB TEMPERATURES AROUND -3C. THE
AIR MASS IS RATHER UNSTABLE...BUT WITH ABUNDANT MOISTURE ALOFT THE
CAPE IS ONLY AROUND 300J/KG AND THE CAPE PROFILE IS SKINNY. AS THE
CENTER OF THE UPPER TROUGH MOVED ACROSS THE AREA AROUND 5 PM...QUITE
A FEW THUNDERSTORMS DEVELOPED ACROSS THE NORTHERN INLAND WATERS.
THESE HAVE SINCE DIED OUT AS THEY MOVED INTO THE CANADIAN COASTAL
RANGE. EARLIER...PRES GRADIENTS WERE STRONGLY SOUTHERLY AND NEAR
GALE FORCE SLY WINDS DEVELOPED ACROSS THE INLAND WATERS. NOW THAT
STRONG INFLOW HAS DEVELOPED IN THE STRAIT OF JUAN DE FUCA...THE SW
WINDS OVER THE INLAND VALLEYS WILL GRADUALLY DIE DOWN. AN AREA OF
CONVERGENCE IS CENTERED OVER SKAGIT COUNTY THIS EVENING. AS THE
UPPER TROUGH MOVES EAST AND FLOW BECOMES MORE WESTERLY AND RELAXES
SOMEWHAT...EXPECT A PUGET SOUND CONVERGENCE ZONE TO SET UP AROUND
THE EVERETT AREA AND CONTINUE NORTH OF THE SEATTLE AREA OVERNIGHT
BEFORE DISSIPATING. SNOW LEVELS IN THE MOUNTAINS SHOULD AVERAGE
AROUND 2000 FT AND HIGH END ADVISORY AMOUNTS OF SNOW ARE POSSIBLE IN
THE NORTH CASCADES NORTH OF STEVENS PASS IN SNOHOMISH AND SKAGIT
COUNTIES.
A DEVELOPING FRONTAL SYSTEM IS SEEN AHEAD OF A LEADING EDGE OF A 140
KT JET STREAK NEAR 44N/159W. THE 00Z NAM AND GFS SOLUTIONS ARE IN
AGREEMENT WITH THEIR 18Z RUNS IN DEVELOPING THIS WAVE TO ABOUT 990
MB AND SLAMMING IT INTO THE PAC NW SOMEWHERE BETWEEN THE MOUNT OF
THE COLUMBIA RIVER...NAM12...AND THE CHEHALIS GAP BEFORE TAKING IT
NE INTO THE CENTRAL TO NORTH CASCADES SAT NIGHT. MODERATELY STRONG
WINDS WITH MARINE GALES WILL ACCOMPANY THIS LOW...BUT WIND SPEEDS
AND DIRECTIONS WILL BE QUITE DEPENDENT ON THE UNCERTAIN TRACK OF
THIS FAST MOVING LOW. IF THERE WERE ANY COOL AIR AROUND OR HIGHER
PRES N AND EAST OF THE AREA...WE WOULD NEED TO WATCH OUT FOR LOWLAND
SNOW IN ADVANCE OF AND TO THE NORTH OF THE TRACK OF THE LOW WITH WET
BULB COOLING IN THE DEFORMATION ZONE TO THE NORTH. HOWEVER...ALL
MODELS SHOW TEMPERATURES BETWEEN 2000 FT AND THE SURFACE TO BE 2-4
DEG C TOO WARM...WHICH IS CONSISTENT WITH THE MARINE AIR MASS IN
PLACE AND THE SOMEWHAT SPLIT NATURE OF THIS NEXT INCOMING SYSTEM.
1.0 TO 1.5 INCHES OF PRECIPITATION ARE SEEN TO THE NORTH OF THE
TRACK OF THE LOW SAT NIGHT. WITH SNOW LEVELS AROUND 2000 FT AND
PRECIPITATION AMOUNTS OF THIS DEGREE...WILL ISSUE A WINTER STORM
WATCH FOR ALL OF THE MOUNTAINS SAT NIGHT THROUGH MIDDAY SUN.
CONDITIONS BRIEFLY DRY LATER SUN AFTERNOON INTO SUN NIGHT BETWEEN
SUN MORNINGS DEPARTING LOW AND THE NEXT FRONTAL SYSTEM THAT MOVES IN
MON OR MON NIGHT.
WILL UPDATE THE ZONES TO REFINE THE SHORT TERM AND TO ADD THE WINTER
STORM WATCH FOR THE MOUNTAINS SAT NIGHT THROUGH MIDDAY SUN. ALBRECHT
.LONG TERM...PREVIOUS LONG TERM DISCUSSION FOLLOWS...A WARM FRONT
MOVES THRU WRN WA MONDAY...AT 700MB THE TEMP WARMS FROM -14C LATE
SUN TO ARND -5C MON AFTERNOON. THE SURFACE PRES PATTERN IS RATHER
LACKLUSTER WITH THIS FRONT ON MONDAY...THE NAM SHOWS A FAIRLY DECENT
SE GRADIENT MONDAY MORNING BUT THEN BY MONDAY EVENING THE FRONT IS
DISSIPATING AND PRES IS RISING WITH LIGHT GRADIENTS AS 500MB HEIGHTS
RISE INTO THE LOWER 560S. THERE IS A GOOD CHANCE OF SOME DRY WEATHER
TUE AS THAT RIDGE BUILDS IN...THEN A FNTL BAND MOVES THRU WED OR
THU...OR BOTH. THE LATEST GFS SUGGESTS THE REMNANTS OF A WEAKENING
FNTL BAND FOR WED AND THEN A STRONGER SYS THU. THERE IS PRETTY GOOD
AGREEMENT THAT THE FIRST HALF OF THE WEEK WILL SEE A FAIRLY HIGH
FREEZING LEVEL BUT NOT MUCH PRECIP...AND THEN A LOWERING SNOW LEVEL
LATE IN THE WEEK WITH THE BEST GUESS FOR A DECENT COLD FROPA THU
NIGHT...SO FRIDAY COULD BE POSTFRONTAL AND COOL SHOWERY BUT I
HAVEN`T GONE FOR THAT MUCH DETAIL FOR A DAY SEVEN FCST THO I DID
SHOW THE SNOW LEVEL BACK BELOW THE PASSES BY FRIDAY FOR BETTER
SKIING LIKELY TOWARD THE END OF NEXT WEEK. 19
&&
.HYDROLOGY...PRECIPITATION HAS BECOME SHOWERY. WHILE 0.5-1.0 INCHES
OF PRECIPITATION ARE LIKELY IN THE NORTH CASCADES TONIGHT AND EARLY
SATURDAY...SNOW LEVELS WILL BE AROUND 2000 FT AND AFFECTS ON THE
RIVERS SHOULD BE MINIMAL.
THE SKOKOMISH RIVER IS FORECAST TO FALL BELOW FLOOD STAGE ABOUT NOON
SATURDAY. THERE WILL BE A PLANNED RELEASE OF 3000 CFS FROM CUSHMAN
DAM #2 INTO THE NORTH FORK SKOKOMISH RIVER ON SATURDAY. THIS RELEASE
WILL KEEP THE SKOKOMISH RIVER RUNNING HIGH. THE FORECAST CALLS FOR
THE RIVER TO REMAIN JUST BELOW FLOOD STAGE SATURDAY NIGHT AND SUNDAY.
THE SATSOP RIVER AT SATSOP HAS JUST FALLEN BELOW FLOOD STAGE AROUND
730 PM THIS EVENING. WILL LIKELY TAKE THE FLOOD WARNING FOR THE
SATSOP DOWN BY 10 PM.
THE LOWEST REACH OF THE CHEHALIS WILL BOUNCE AROUND AT A FOOT OR
LESS BELOW FLOOD STAGE THROUGH SATURDAY. MORE RAIN SATURDAY NIGHT
COULD KEEP THE THE LOWER CHEHALIS NEAR FLOOD STAGE. WILL MAINTAIN
THE FLOOD WATCH FOR THE CHEHALIS THROUGH SUNDAY FOR NOW. IF FLOODING
DOES OCCUR IT SHOULD BE MINOR.
ANOTHER SYSTEM WILL ARRIVE SATURDAY NIGHT INTO SUNDAY MORNING WITH
SIGNIFICANT PRECIPITATION IN THE MOUNTAINS. SNOW LEVELS WILL REMAIN
LOW THROUGH SUNDAY...AROUND 2000 FT...SO RENEWED FLOODING IS NOT
EXPECTED.
THE NEXT SYSTEM ON MONDAY SHOULD MOVE THROUGH QUICKLY AND BE TOO
WEAK TO CAUSE ANY FLOODING...EVEN WITH RISING SNOW LEVELS. FOR THE
REMAINDER OF THE WEEK...THE AIR MASS OVER THE NORTHWEST WILL BE
WARMER WITH HIGHER SNOW LEVELS...HOWEVER THE SYSTEMS THAT ARE
EXPECTED TO AFFECT THE AREA WILL BE FAIRLY WEAK AND ARE NOT EXPECTED
TO CAUSE ANY ADDITIONAL FLOODING CONCERNS.
NO FLOODING IS EXPECTED AT ANY TIME ON THE GREEN RIVER.
ALBRECHT/BURKE
&&
.AVIATION...AN UPPER TROF OVER WRN WA WILL CONTINUE MOVING E. BY
EARLY SATURDAY...THIS SYSTEM WILL BE OVER THE GREAT BASIN. A
WEAK...UPPER RIDGE WILL FOLLOW ON THE HEELS OF THE UPPER TROF.
CONTINUED WLY FLOW ALOFT. THE AIR MASS WILL REMAIN MOIST. SLIGHTLY
UNSTABLE ATMOSPHERE OVER THE AREA WILL BECOME STABLE OVERNIGHT.
AT THE SFC...STRONG ONSHORE FLOW WILL WEAKEN OVERNIGHT. ANOTHER
FRONTAL SYSTEM WILL APPROACH THE REGION DURING THE DAY SATURDAY FOR
INCREASED SLY FLOW. CIGS WILL GENERALLY BE IN THE 4-8K FT RANGE...
ALTHOUGH EXPECT AREAS OF CIGS NEAR 2K FT. THERE MAY BE SOME PATCHY
FOG...REDUCING VSBYS DOWN TO 3SM...LATER TONIGHT OR EARLY SATURDAY
MORNING OVER THE SW INTERIOR IF THERE IS SUFFICIENT CLEARING.
CONCERNING THE PUGET SOUND CONVERGENCE ZONE /PSCZ/...IT APPEARED
THAT THE PSCZ WAS DEVELOPING OVER ITS FAVORED POSITION...JUST N OF
THE KING/SNOHOMISH COUNTY BORDER WHERE IT WILL REMAIN STATIONARY.
WOULD NOT RULE OUT AN ISOLATED LIGHTNING STRIKE WITHIN THE PSCZ TIL
MIDNIGHT. THE PSCZ WILL DISSIPATE LATE TONIGHT AS THE FLOW BECOMES
UNFAVORABLE FOR MAINTAINING IT.
KSEA...CIGS WILL GENERALLY BE IN THE 5-8K FT RANGE OVERNIGHT BUT
EXPECT OCCASIONAL CIGS NEAR 2500 FT. SLY WINDS WILL DIMINISH
OVERNIGHT.
&&
.MARINE...STRONG WESTERLY FLOW WILL WEAKEN AND BECOME SOUTHERLY
OVERNIGHT. A FRONTAL SYSTEM WILL APPROACH THE AREA DURING THE DAY
SATURDAY... RESULTING IN INCREASED SOUTHERLY FLOW. THE COLD OR
OCCLUDED FRONT IS EXPECTED TO MOVE ACROSS THE AREA SATURDAY NIGHT.
ONSHORE FLOW WILL CONTINUE ON SUNDAY BETWEEN SYSTEMS. THE NEXT
FRONTAL SYSTEM WILL AFFECT THE WATERS ON MON.
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WARNINGS AND/OR FLOOD WATCHES ARE IN EFFECT FOR
A PORTION OF THE CWA.
.A WINTER WEATHER ADVISORY IS IN EFFECT FOR THE CASCADES
TONIGHT.
.A WINTER STORM WATCH IS IN EFFECT FOR SATURDAY NIGHT THROUGH
MIDDAY SUNDAY IN THE OLYMPICS AND NORTH AND CENTRAL CASCADES
AND PASSES.
PZ...A GALE WARNING REMAINS IN EFFECT FOR THE CENTRAL AND
EASTERN STRAIT OF JUAN DE FUCA TIL MIDNIGHT.
.GALE WARNINGS ARE IN EFFECT FOR THE COASTAL WATERS AND
WEST ENTRANCE TO THE STRAIT OF JUAN DE FUCA SATURDAY
THROUGH SATURDAY EVENING.
.A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE PUGET SOUND
AND HOOD CANAL TIL 4 AM SATURDAY.
.A GALE WATCH IS IN EFFECT FOR THE NORTHERN INLAND WATERS
FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING.
.A SMALL CRAFT ADVISORY FOR ROUGH GRAYS HARBOR BAR
CONDITIONS IS IN EFFECT TIL 10 AM SUNDAY.
$$
WWW.WEATHER.GOV/SEATTLE
FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML.
000
FXUS66 KPQR 210410
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
809 PM PST FRI NOV 20 2009
.SYNOPSIS...RESIDUAL SHOWERS WILL CONTINUE THE REMAINDER OF THE NIGHT
AFTER THE PASSAGE OF A COLD FRONT. ANOTHER FRONT APPROACHES LATER
SATURDAY...WITH STRONG WINDS POSSIBLE ON THE COAST AND
SIGNIFICANT SNOW EXPECTED IN THE CASCADES. THE NEXT STORM ARRIVES
LATER MONDAY.
&&
.SHORT TERM...STILL CONSIDERABLE SHOWERS THIS EVENING...ESPECIALLY
ALONG THE CASCADES AND WILL KEEP THE ADVISORY FOR SNOW. A WARM FRONT
APPROACHES SATURDAY WITH INCREASING WINDS ALONG THE COAST CONSISTENT
WITH HIGH WIND WATCH.
THE TRAILING COLD FRONT GETS SLOWED BY A WAVE WITH ANOTHER LOW
DEVELOPING. THE LOWS PUSHES TO THE COAST SATURDAY NIGHT. ALL THE
MODELS HAVE VARIED SOLUTIONS...MANY OF WHICH WOULD RESULT IN
SIGNIFICANT WINDS IN THE INTERIOR AT FIRST LOOK. BUT...THE UPPER
TROUGH BECOMES NEGATIVELY TILTED...SOMEWHAT MORE IN THE NAM THAN THE
GFS...WITH MOMENTUM TRANSFERRING SOUTH. NOT GOOD FOR A STRONG
SOUTHERLY PUSH OF WINDS. ALSO THE SURFACE LOW IS FILLING AS IT MOVES
INLAND AND THE LOW IS NOT MOVING NORTH OR NORTH NORTHEASTWARD
ALLOWING THE STRONG UP VALLEY PUSH OF WINDS.
SO WILL WAIT TO SEE IF WE GET A BETTER AND MORE CONSISTENT LOOK ON
LATER RUNS ON DEALING WITH THE WINDS. WITH THAT SECOND WAVE SLOWING
THINGS DOWN...WILL EXPAND THE WINTER STORM WATCH TO COVER ALL DAY
SUNDAY IN THE CASCADES RATHER THAN JUST THE MORNING. SS
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...WEAK HIGH PRES
BUILDS OVER THE FORECAST AREA MON NIGHT.
MODELS SHOW A WEAK SYSTEM APPROACH THE COAST EARLY TUE...BUT IT
TRACKS FURTHER NORTH AND LIGHTLY BRUSHES THE FAR NORTHWEST CORNER OF
THE CWA. THIS RIDGE IS MORE PERSISTENT THAN PREVIOUS MODEL RUNS
SUGGESTED. IT MANAGES TO DELAY THE ARRIVAL OF A SECOND SYSTEM
THROUGH THUR. BY MID NEXT WEEK...MODELS DISAGREE ON THE SOLUTION FOR
THE WEEKEND. GFS MODEL RUNS ARE INCONSISTENT...THE 06Z RUN HELD BACK
ON PRECIP THROUGH THURS NIGHT BUT THE CURRENT RUN SHOWS RAIN
EXTENDING TO THE CASCADES THURS NIGHT. SO FAR...MODELS SUGGEST A
FAIRLY NICE WEEKEND AS ANOTHER UPPER HIGH PRES TEMPORARILY SETS UP
OVER THE PAC NW. LRAMIREZ
&&
.AVIATION...COOL SHOWERS CONTINUE TO STREAM IN OFF THE PACIFIC THIS
EVENING IN UNSTABLE WESTERLY FLOW. VFR CONDITIONS ARE EXPECTED
ACROSS ALL AREAS TONIGHT WITH A 40% CHANCE OF MVFR CONDITIONS IN AND
NEAR SHOWERS. A WARM FRONT WILL BRING RAIN AND MVFR CONDITIONS TO
THE COAST AND COAST RANGE BY MIDDAY SATURDAY.
KPDX AND APPROACHES...CONDITIONS ARE EXPECTED TO REMAIN PRIMARILY
VFR TONIGHT WITH A 40% CHANCE OF MVFR CONDITIONS IN AND NEAR
SHOWERS. VFR CONDITIONS ARE EXPECTED SATURDAY.
&&
.MARINE...SMALL CRAFT WINDS WILL CONTINUE THROUGH SATURDAY MORNING
BEFORE THE NEXT STRONGER FRONT BOOSTS GUSTS TO LOW END GALE CRITERIA
SATURDAY AFTERNOON WITH THE POSSIBILITY OF ANOTHER WAVE GENERATING
STRONG GALES AND POSSIBLY STORM FORCE WINDS BY LATE SATURDAY NIGHT
INTO SUNDAY MORNING. SEAS CURRENTLY HOVERING AROUND 12 FT AND SHOULD
BUILD TO 16 TO 18 BY SATURDAY NIGHT.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
WA/OR...SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR
THROUGH SAT EVENING.
SMALL CRAFT ADVISORY FOR WINDS CAPE SHOALWATER TO
FLORENCE THROUGH SAT MORNING.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS CAPE SHOALWATER TO
FLORENCE THROUGH SAT MORNING.
GALE WARNING CAPE SHOALWATER TO CASCADE HEAD SAT MORNING
THROUGH LATE SATURDAY NIGHT.
GALE WARNING CASCADE HEAD TO FLORENCE SAT MORNING THROUGH
SATURDAY EVENING.
STORM WATCH CASCADE HEAD TO FLORENCE SAT EVENING THROUGH
SUNDAY MORNING.
SNOW ADVISORY FOR THE SOUTH WASHINGTON AND NORTH OREGON
CASCADES THROUGH SAT MORNING.
WINTER WEATHER WATCH FOR SNOW FOR THE SOUTH WASHINGTON AND
NORTH OREGON CASCADES AND THE CASCADES IN LANE COUNTY FOR
SATURDAY AFTERNOON THROUGH SUNDAY.
HIGH WIND WATCH FOR THE NORTHERN AND CENTRAL OREGON COAST
FOR SAT AFTERNOON AND NIGHT.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
000
FXUS66 KOTX 210330
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
730 PM PST FRI NOV 20 2009
.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH THE REGION THIS EVENING AND BRING
LIGHT VALLEY RAIN AND MOUNTAIN SNOW TO THE REGION. AFTER A SHORT
BREAK IN THE WEATHER ON SATURDAY...A STRONGER AND COLDER STORM
SYSTEM WILL BRING THE POTENTIAL FOR MODERATE MOUNTAIN AND VALLEY
SNOW ACCUMULATIONS SATURDAY NIGHT AND INTO SUNDAY. A SERIES OF
STORM SYSTEMS WILL CONTINUE TO PASS THROUGH THE INLAND NORTHWEST
EVERY 24 TO 36 HOURS WELL INTO NEXT WEEK.
&&
.DISCUSSION...
MINOR UPDATE TO THE FORECAST FOR THE REST OF TONIGHT CONCERNING
PRECIPITATION CHANCES. COLD FRONT AS OF 7 PM WAS LOCATED NEAR THE
WASHINGTON/IDAHO BORDER WHERE A BAND OF STEADY RAIN AND MOUNTAIN
SNOW EXISTS. BEHIND THE FRONT DOWNSLOPE WESTERLY FLOW OFF THE
CASCADES HAS ENDED THE PRECIPITATION AT OMAK AND MOSES LAKE WITH
THE BACK EDGE OF THE PRECIPITATION OVER WESTERN SPOKANE AND
WHITMAN COUNTIES. AS THE FRONT CONTINUES TO MOVE EAST TONIGHT
AREAS WHERE RAIN HAS NOT YET DEVELOPED OVER SE WA/N IDAHO WILL
SOON SEE PRECIP DEVELOP TO AS THE FRONT CONTINUES TO MOVE EAST.
THUS...POPS OF 80-100 PCT REMAIN IN THE FCST FOR THE REST OF
TONIGHT IN THESE AREAS. CURRENT FORECAST LOOKS GOOD...BUT WILL
LIKELY UPDATE LATER TO LOWER POPS OVER FAR EASTERN WASHINGTON AS
THE FRONT EXITS THE AREA. JW
&&
.AVIATION...
FROM PREVIOUS DISCUSSION...A COLD FRONT WILL MOVE ACROSS THE FORECAST
THIS EVENING AND BE EAST OF THE AREA LATER TONIGHT. CONDITIONS
WILL BE MAINLY VFR WITH LOCALIZED AND BRIEF MVFR CEILINGS DURING
THE HEAVIEST PRECIPITATION. CONDITIONS WILL DRY OUT FROM THE WEST
BEHIND THE COLD FRONT AND EXPECT ENOUGH WIND TO KEEP THE LOWER
ATMOSPHERE MIXED ENOUGH FOR ONLY ISOLATED STRATUS DEVELOPMENT
SATURDAY MORNING. AFTER 16Z SATURDAY...SOUTHWEST WINDS WILL
INCREASE WITH GUSTS 20 TO 25 KTS. PRECIPITATION WILL AFFECT THE
WESTERN TAF SITES AFTER 18Z. /EK
&&
.PRELIMINARY POINT TEMPS/POPS...
SPOKANE 33 39 32 37 27 39 / 80 20 90 80 10 40
COEUR D`ALENE 33 39 31 37 28 40 / 100 20 80 70 20 50
PULLMAN 32 39 32 36 28 42 / 90 20 70 80 20 40
LEWISTON 36 47 36 41 30 48 / 70 10 40 90 20 30
COLVILLE 32 40 33 40 28 38 / 80 30 80 50 10 60
SANDPOINT 32 36 32 37 28 36 / 90 40 80 60 20 60
KELLOGG 32 33 30 34 27 35 / 90 70 90 90 40 60
MOSES LAKE 31 45 32 43 26 43 / 10 10 80 60 0 40
WENATCHEE 32 43 32 43 29 41 / 0 30 90 50 10 50
OMAK 28 43 31 42 25 40 / 10 60 90 60 0 60
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&
$$
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