[top]
000
FXUS65 KTFX 212151
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
251 PM MST SAT NOV 21 2009
.DISCUSSION...
THE UPPER LEVEL TROUGH THAT MOVED THROUGH HE REGION EARLIER TODAY
WILL EXIT IT THE REGION TONIGHT FOLLOWED BY A BRIEF PERIOD OF
DRYING UNDER WEAK UPPER LEVEL RIDGING. WIDELY SCATTERED SNOW
SHOWERS OVER THE MTNS WILL DIMINISH EARLY THIS EVENING WITH A FEW
ISOLATED SNOW SHOWERS POSSIBLE THROUGH EARLY THIS EVENING AS WELL
ALONG THE CANADIAN BORDER IN ASSOCIATION WITH A WEAK DISTURBANCE
MOVING SOUTHEAST FROM ALBERTA. CLOUDS AND MOISTURE WILL INCREASE
AGAIN ON SUNDAY AS A VIGOROUS PACIFIC STORM SYSTEM MOVES ONSHORE
AND QUICKLY MOVES TO THE NORTHERN ROCKIES BY SUNDAY EVENING AND
ACROSS THE STATE SUNDAY NIGHT. THIS SYSTEM WILL BRING ANOTHER
PERIOD OF SNOW TO THE MOUNTAINS SUNDAY AFTERNOON AND EVENING WITH
SNOW SHOWERS POSSIBLE ELSEWHERE. MOIST AND UNSTABLE WEST TO
NORTHWEST FLOW WILL MAINTAIN AT LEAST A CHANCE OS SNOW SHOWERS
OVER THE CENTRAL AND SW MT MTNS THROUGH SUNDAY NIGHT.
ACCUMULATIONS OF AN INCH OR LESS ARE EXPECTED ACROSS THE VALLEYS
OF SW MT WITH 1 TO 3 INCHES POSSIBLE IN THE MTNS. THE MOST
PERSISTENT SNOW WILL OCCUR OVER THE GALLATIN AND MADISON MTN
RANGES WHERE HIGHER AMOUNTS OF 3 TO 5 INCHES APPEAR LIKELY FOR
ELEVATIONS ABOVE 6000 FT THROUGH SUNDAY NIGHT. UPPER LEVEL RIDGING
BUILDS IN BEHIND THIS SYSTEM ON MONDAY FOR DRIER CONDITIONS.
TEMPERATURES WILL REMAIN SEASONABLY COOL THROUGH MONDAY WITH
CLEARING SKIES TONIGHT ALLOWING TEMPS TO DROP INTO THE SINGLE
DIGITS OR LOWER IN SOME OF THE SW MT VALLEYS. HOENISCH
MONDAY NIGHT THROUGH SATURDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT INTO THE MIDDLE OF NEXT WEEK. BOTH MODELS BRING A
WEAK SHORTWAVE TROUGH OVER AN UPPER LEVEL HIGH PRESSURE RIDGE PARKED
ALONG THE PACIFIC COAST THROUGH THE AREA MONDAY NIGHT INTO
TUESDAY...WHICH WILL BRING A CHANCE OF PRECIPITATION TO THE AREA.
THIS SHORTWAVE WILL ALSO BRING STRONG AND GUSTY WESTERLY DOWNSLOPE
WINDS TO THE AREA...WHICH WILL LIMIT PRECIPITATION OVER THE PLAINS
AND WARM TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE SEASONAL
AVERAGES. BOTH MODELS THEN AMPLIFY AND SHIFT THE UPPER RIDGE INTO
MONTANA TUESDAY NIGHT INTO THURSDAY. THIS RIDGE WILL KEEP THE AREA
WARM (TEMPERATURES 10 TO 15 DEGREES ABOVE NORMAL) AND MOSTLY DRY.
GUSTY WESTERLY SURFACE WINDS WILL INCREASE AGAIN WEDNESDAY NIGHT
INTO THURSDAY (THANKSGIVING DAY) AS THE NEXT SYSTEM APPROACHES THE
AREA. THE MODELS BEGIN TO DIFFER ON THURSDAY. UNLIKE THE MODEL RUNS
FROM LAST NIGHT...THE ECMWF BRINGS THE NEXT PACIFIC SYSTEM THROUGH
THE STATE QUICKER THAN THE GFS. WITH THIS UNCERTAINTY...HAVE KEPT
NEAR CLIMATOLOGICAL CHANCES OF PRECIPITATION OVER THE TFX CWA FRIDAY
THROUGH SATURDAY...WITH TEMPERATURES COOLING TO NEAR SEASONAL
NORMALS BY SATURDAY. AN UPPER LEVEL RIDGE THEN BEGINS TO MOVE INTO
THE WESTERN UNITED STATES SATURDAY NIGHT...WHICH SHOULD CAUSE THE
CHANCE FOR PRECIPITATION TO DECREASE. UPPER LEVEL SUPPORT FOR THE
INCREASING WINDS THROUGH THIS PERIOD IS TEMPORARY. THEREFORE...AM
NOT ANTICIPATING HIGH WIND HIGHLIGHTS AT THIS TIME AND WILL NOT
MENTION IN THE HAZARDOUS WEATHER OUTLOOK. HOWEVER...THE POTENTIAL
FOR BRIEF PERIODS OF STRONG WINDS STILL REMAINS...AND THE SITUATION
WILL CONTINUE TO BE MONITORED. COULSTON
&&
.AVIATION...
UPDATED 1740Z.
AN UPPER LEVEL LOW PRESSURE TROUGH WILL CONTINUE TO MAKE ITS WAY
ACROSS CENTRAL MT THIS AFTN/EVE. MOST OF ASSOCIATED MOISTURE HAS
ALREADY PUSHED TOWARD KBIL BUT LOCATIONS WEST OF A KBIL-TO-KHLN LINE
WILL SEE A FEW RESIDUAL SNOWSHOWERS THROUGH MID-AFTN. CEILINGS
SHOULD REMAIN VFR ACROSS THE REGION...THOUGH HIGHER TERRAIN WILL BE
OBSCURED WITH MVFR/IFR CONDITIONS NEAR ANY PRECIPITATION AREAS.
WINDS WILL BE GUSTY OVER THE PLAINS AND ROCKY MTN FRONT THIS AFTN
WITH WIDESPREAD GUSTS OF 25 TO 35 KTS...AND SOME LOCATIONS FROM
GLACIER NP TO KHVR SEEING GUSTS OF 40 TO 50 KTS. AS THE TROUGH
MOVES FURTHER EAST THIS EVE...WINDS SHOULD DECREASE TOWARD SUNSET
AND SKIES WILL BE MOSTLY CLEAR OVERNIGHT AT ALL TERMINALS.
WARANAUSKAS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 24 38 29 42 / 0 20 20 0
CTB 22 36 28 40 / 0 20 20 0
HLN 22 38 28 39 / 0 40 30 10
BZN 9 36 17 35 / 0 60 40 10
WEY 3 27 11 26 / 30 90 80 20
DLN 13 31 16 30 / 0 60 40 0
HVR 19 41 25 45 / 20 20 10 10
LWT 19 37 22 38 / 0 40 40 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HOENISCH
LONG TERM...COULSTON
AVIATION...WARANAUSKAS
WEATHER.GOV/GREATFALLS
[top]
000
FXUS65 KMSO 212146
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
246 PM MST SAT NOV 21 2009
.DISCUSSION...SHOWER ACTIVITY IS EXPECTED TO WANE THIS EVENING AS
A SHORTWAVE RIDGE BUILDS AHEAD OF AN APPROACHING UPPER LEVEL
TROUGH. THIS WILL ALLOW SKIES TO CLEAR ENOUGH TO SEE A QUICK DROP
IN TEMPERATURES AFTER SUNSET AND THE POTENTIAL FOR SOME VALLEY FOG
FORMATION...MAINLY IN NORTH CENTRAL IDAHO VALLEYS.
THE UPPER LEVEL TROUGH IS EXPECTED TO BEGIN TO MOVE THROUGH THE
NORTHERN ROCKIES DURING THE DAY SUNDAY. THIS FEATURE WILL BE
ACCOMPANIED WITH A STRONG UPPER LEVEL JET AND SURFACE COLD
FRONT...WHICH WILL COMBINE WITH ABUNDANT MOISTURE TO PRODUCE
WIDESPREAD PRECIPITATION OVER MOST ALL OF WESTERN MONTANA AND
NORTH CENTRAL IDAHO. TEMPERATURES ARE EXPECTED TO REMAIN COOL
ENOUGH THAT ALL BUT THE LOWEST VALLEYS (BELOW 2500 FEET) SHOULD
SEE PRECIPITATION FALL AS SNOW. THE MOST FAVORABLE DYNAMICS WITH THIS
SYSTEM WILL BE FOCUSED OVER NORTH CENTRAL IDAHO HOWEVER...AND THUS
THE BEST SNOW PRODUCTION IS EXPECTED OVER THE CLEARWATER AND
BITTERROOT MOUNTAINS. IN ADDITION TO EXPECTED ACCUMULATING
SNOW IN THESE AREAS...GUSTY SOUTHWEST TO WEST WINDS WILL CREATE LOWERED
VISIBILITY AND HAZARDOUS DRIVING CONDITIONS OVER PORTIONS OF
NORTHCENTRAL IDAHO AND WESTERN MONTANA. A WINTER WEATHER ADVISORY
HAS BEEN ISSUED...PLEASE SEE WWW.WEATHER.GOV/MISSOULA FOR FURTHER
DETAILS. THE UPPER LEVEL TROUGH WILL MOVE EASTWARD OVERNIGHT
SUNDAY...BRINGING A NORTHWESTERLY FLOW OVER THE REGION. WHILE THE
HEAVIEST PRECIPITATION SHOULD COME TO AN END...THERE IS THE
POSSIBILITY OF BANDED PRECIPITATION DEVELOPING IN TO MONDAY.
TUESDAY THROUGH SUNDAY...A SHORTWAVE TROUGH WILL PASS TO THE NORTH
ALONG THE MONTANA CANADIAN BORDER ON TUESDAY BRINGING A CHANCE FOR
PRECIPITATION IN NORTHWEST MONTANA BEFORE A HIGH PRESSURE RIDGE
BEGINS TO OVERTAKE THE REGION. THIS HIGH PRESSURE HAS BEEN SHOWING
SIMILAR TIMING AND SLIGHTLY DIFFERENT AMPLITUDES BETWEEN THE ECMWF
AND THE GFS. THE AMPLIFYING RIDGE WILL POSE A THREAT OF WIDESPREAD
VALLEY FOG STARTING WEDNESDAY MORNING. MODEL PLAN VIEWS AND CROSS
SECTIONS SHOW ENERGY PASSING THROUGH THE RIDGE WEDNESDAY MORNING...
WHICH COULD INHIBIT VALLEY INVERSION DEVELOPMENT...HOWEVER...MODEL
SOUNDING FOR THE SAME TIME FRAME DO SHOW INVERSIONS
INITIATING...SO WILL KEEP THE MENTION OF FOG IN THE FORECAST. HIGH
PRESSURE LOOKS TO LINGER INTO THURSDAY WITH DRIER...SUBSIDING AIR
AND STRONG INVERSIONS FORECAST BY MODEL SOUNDINGS. THIS IS
SOMEWHAT DIFFERENT FROM YESTERDAY...BUT THESE FEATURES WOULD
PROMOTE FOG ON THURSDAY. WILL CONTINUE TO MONITOR FOG POTENTIAL
ESPECIALLY FOR THE GLACIER PARK INTERNATIONAL AIRPORT AND THE
MISSOULA AIRPORT AS HOLIDAY AIRLINE TRAVEL MAY BECOME ADVERSELY EFFECTED.
&&
.AVIATION...STRONG WEST-SOUTHWEST SURFACE WINDS WILL CONTINUE THROUGH
EARLY SATURDAY EVENING AND CLOUDS WILL BE ON THE INCREASE AS THE
NEXT PACIFIC WEATHER SYSTEM PUSHES INTO THE NORTHERN ROCKIES. SNOW
SHOWERS WILL START TO SPREAD ACROSS THE IDAHO PANHANDLE AND
NORTHWEST MONTANA SUNDAY MORNING...MOSTLY AFTER 22/1200Z. THE
REMAINDER OF WESTERN MONTANA AND NORTH CENTRAL IDAHO WILL SEE
SHOWERS SPREAD AREAWIDE LATER MIDDAY SUNDAY. SIGNIFICANTLY
LOWERED CEILINGS AND REDUCTIONS IN VISIBILITY WILL BE POSSIBLE
WITH HEAVIER SNOW SHOWERS AT THE TERMINALS. SURFACE WINDS WILL
REMAIN BREEZY... BUT TO A LESSER DEGREE THAN WINDS OBSERVED ON
SATURDAY. OBSCURATIONS OF MOUNTAINS AND PASSES CAN BE EXPECTED.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY FROM 8 AM TO 11 PM MST SUNDAY FOR
LOWER CLARK FORK REGION.
WINTER WEATHER ADVISORY FROM 8 AM TO 11 PM MST SUNDAY FOR
BITTERROOT/SAPPHIRE MOUNTAINS.
ID...WINTER WEATHER ADVISORY FROM 7 AM TO 10 PM PST SUNDAY FOR
OROFINO/GRANGEVILLE REGION.
WINTER WEATHER ADVISORY FROM 7 AM TO 10 PM PST SUNDAY FOR
NORTHERN CLEARWATER MOUNTAINS-SOUTHERN CLEARWATER MOUNTAINS.
&&
$$
SHORT TERM...PALLISTER
LONG TERM....KITSMILLER
AVIATION...NOLTE
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000
FXUS65 KBYZ 212145
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
245 PM MST SAT NOV 21 2009
.SHORT TERM...VALID FOR SUN AND MON...
AIRMASS FAIRLY DRY IN A POST FRONTAL ENVIRONMENT WITH GUSTY
NORTHWEST WINDS PERSISTING OVER THE EASTERN ZONES. UPPER LEVEL
TROUGH OVER THE AREA WILL BEGIN YIELDING TO A SHORTWAVE RIDGE
TONIGHT INDUCED BY A MUCH STRONGER SYSTEM PUSHING INTO THE PACIFIC
NORTHWEST. AREAS OF PRECIP LINGERING SOUTH WEST OF KBIL AND THINK
THAT AS THIS ACTIVITY SHIFTS EASTWARD IT WILL PERSIST SINCE IT
WILL BE SHIFTING AWAY FROM DOWNSLOPE INFLUENCES. THIS ACTIVITY
SHOULD CLEAR AFTER MIDNIGHT AND WILL HAVE A CHANCE FOR
TEMPERATURES TO FALL SHARPLY WITH CLEARING SKIES AND LOW DEWPOINTS.
HOWEVER...BY MORNING PRESSURE FALLS BEGIN QUICKLY ALONG THE
NORTHERN ROCKY FRONT AS THE NEXT WAVE MOVES EASTWARD ACROSS
WASHINGTON. A BRIEF PERIOD OF GAP FLOW WINDS WILL DEVELOP LATE
TONIGHT AND EARLY SUNDAY WITH STRONG SURFACE HIGH PRESSURE OVER
SOUTHEAST IDAHO WAITING FOR THE LEESIDE TROUGH TO FORM. THIS
SYSTEM IS EXPECTED TO FILL AS IT MOVES EASTWARD BUT IS STILL
PRETTY STRONG SO EXPECT AN INCREASE IN MOUNTAIN PRECIPITATION AND
HAVE ACCUMULATIONS MENTIONED BUT THINK THAT LOW LEVEL AIRMASS
OVER THE PLAINS WILL BE FAIRLY DRY AND PRECIP WILL HAVE A HARD
TIME REACHING THE GROUND. COLDER HEIGHTS ALOFT WILL KEEP
TEMPERATURES COOLER THAN TODAY BUT CLOSE TO 40 DEGREES IS
SEASONABLE FOR THIS TIME OF YEAR. GRADIENTS FOR WINDS WEAKEN A BIT
ON SUNDAY BUT AIRMASS WILL BE UNSTABLE AND MOMENTUM ALOFT WILL
HAVE AN EASY TIME MIXING DOWN. UPPER LOW FILLS AS IT GOES FROM
NORTHWEST MONTANA TO SOUTHEAST MONTANA SUNDAY NIGHT AND WHILE
AIRMASS IS STILL PRETTY DRY...CANNOT RULE SOME ISOLATED SHOWERS
BEING SQUEEZED OUT OF THE AIRMASS...ESPECIALLY OVER SOUTHEAST
MONTANA CLOSER TO THE COLDEST AIR ALOFT. HEIGHTS BEGIN TO BUILD
FROM WEST TO EAST ON MONDAY PUSHING ISOLATED SHOWERS INTO THE
DAKOTAS AND BRINGING CLEARING TO THE WESTERN ZONES. PRESSURE
GRADIENTS FOR GAP FLOW WINDS BEGIN TO TAKE SHAPE ON MONDAY NIGHT
AND HAVE BEGIN TO RAMP UP SPEEDS. OTHERWISE LOOKS DRY WITH CLEAR
SKIES AND LOW DEWPOINTS AGAIN SUPPORTING A COOL NIGHT. BORSUM
.LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT...
JUST SOME MINOR CHANGES MADE TO THE EXTENDED FORECAST THIS
AFTERNOON. UPPER LEVEL RIDGE WILL BE OVER THE FORECAST TUESDAY
MORNING AND HAVE DRIED OUT MOST PERIODS FOR THIS PERIOD. UPPER
LEVEL TROUGH SLIDES INTO NORTH DAKOTA TUESDAY AFTERNOON AND
TUESDAY NIGHT WITH SOME WEAK ENERGY MOVING INTO THE FORECAST AREA
AT THIS TIME. MODELS DO HINT AT A LITTLE PRECIP FOR THIS WEAK
SYSTEM SO HAVE SPREAD THE LOW POPS A LITTLE FARTHER WEST. DID ADD
POPS FOR THE CENTRAL AND WESTERN ZONES AS WELL FOR TUESDAY NIGHT.
THIS SYSTEM QUICKLY EXITS BY WEDNESDAY MORNING LEAVING DRY
CONDITIONS AND WARMER TEMPS THROUGH MUCH OF FRIDAY. MODELS BRING
IN THE NEXT SYSTEM ACROSS SOUTHERN CANADA ON FRIDAY NIGHT AND
SATURDAY WHERE THE ECMWF BRINGS THE SYSTEM RIGHT OVER THE
FORECAST AREAS. HAVE KEPT IN LOW POPS FOR MOST AREAS FOR NOW
UNTIL THE MODELS COME INTO BETTER AGREEMENT. SOLUM
&&
.AVIATION...
GUSTY WINDS UP TO 30 KNOTS WILL CONTINUE ACROSS THE AREA THROUGH
EARLY EVENING BEFORE TAPERING OFF. MVFR CONDITIONS AND MOUNTAIN
OBSCURATIONS WILL CONTINUE TO BE POSSIBLE THROUGH EARLY EVENING
BEFORE BECOMING DRY OVERNIGHT AS SOME ISOLATED RAIN AND SNOW
SHOWERS CONTINUE TO MOVE THROUGH. SOLUM
&&
.PRELIMINARY POINT TEMP/POPS...
SUN MON TUE WED THU FRI SAT
-----------------------------------------------------------
BIL 021/040 028/042 024/046 029/051 031/055 034/051 033/044
02/J 21/B 12/W 20/B 00/U 02/W 22/W
LVM 018/036 023/035 018/043 027/050 030/054 030/046 030/044
04/J 32/S 12/W 20/B 00/U 03/W 32/W
HDN 022/043 024/044 019/047 025/052 028/057 029/053 027/049
02/W 22/O 12/W 20/B 00/U 02/W 22/W
MLS 021/045 024/043 020/047 023/046 026/056 030/051 031/042
01/B 22/O 22/W 00/B 00/U 02/W 22/W
4BQ 020/042 021/042 019/045 022/046 025/056 028/051 028/044
21/N 23/O 12/W 20/B 00/U 02/W 22/W
BHK 020/045 021/040 019/043 023/040 025/054 026/051 028/043
11/B 22/O 22/W 00/B 00/U 02/W 22/W
SHR 019/043 022/039 014/046 022/050 024/056 027/051 024/046
22/W 22/O 12/W 20/B 00/U 02/W 32/W
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
[top]
000
FXUS65 KGGW 212140
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
240 PM MST SAT NOV 21 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH MONDAY...
CURRENT GOES WATER VAPOR IMAGERY REVEALS A LONGWAVE TROUGH NOW IN
PLACE OVER THE WESTERN UNITED STATES. THE LEADING SHORTWAVE TROUGH
HAS NOW LIFTED OVER SASKATCHEWAN AND HAS DRUG A COLD FRONT THROUGH
NORTHEAST MONTANA INTO THE DAKOTAS. A TIGHT SURFACE PRESSURE
GRADIENT HAS DEVELOPED OVER NORTHEAST MONTANA IN THE WAKE OF THESE
FEATURES AND COMBINED WITH COLD AIR ADVECTION TO PRODUCE A STRONG
WEST WIND. A SECONDARY FRONTAL SYSTEM AND ASSOCIATED VORTICITY
MAXIMA IS CURRENTLY DROPPING SOUTHEAST OVER SOUTHEAST ALBERTA AND
SOUTHWEST SASKATCHEWAN. THE VERTICAL ASCENT ASSOCIATED WITH THIS
SYSTEM IS COMBINING WITH DIURNAL HEATING AND CREATING A FEW SNOW
SHOWERS IN CANADA. AS THESE SHOWERS MOVE SOUTH THEY ENCOUNTER A
VERY DRY AIRMASS AND HENCE AT THIS POINT IT APPEAR TO BE PRIMARILY
VIRGA ALONG THE WESTERN PORTION OF THE HI-LINE.
THIS SECONDARY FRONTAL SYSTEM WILL CROSS THE THE LOCAL AREA THIS
EVENING. THE SHOWERS SHOULD WEAKEN AND BEGIN TO DISSIPATE AFTER
SUNSET...BUT THERE MAY BE ENOUGH UPPER FORCING TO MAINTAIN A FEW
WEAK SHOWERS INTO THIS EVENING. THEREFORE...ISOLATED FLURRIES WERE
ADDED TO THE NORTHWEST ZONES THIS EVENING ALTHOUGH ITS MAIN
AFFECT WILL BE INCREASED CLOUD COVER ACROSS THE NORTH AND IT WILL
ALSO MAINTAIN THE WIND THROUGH THE EVENING. ALBEIT MUCH WEAKER AS
LOW-LEVEL LAPSE RATES LESSEN AFTER SUNSET...SO THE CURRENT TIMING
OF THE LAKE WIND ADVISORY SHOULD SUFFICE. SHORTWAVE RIDGING BEGINS
AFTER MIDNIGHT...SO CLOUD COVER SHOULD QUICKLY DECREASE ALONG WITH
THE WIND. MINIMUM TEMPERATURES WILL BE SEASONALLY COOL ACROSS
MOST OF THE REGION.
CLOUD COVER WILL BEGIN TO INCREASE SUNDAY AFTERNOON AS ANOTHER
SHORTWAVE TROUGH DIVES INTO THE PACIFIC NORTHWEST. THIS TROUGH
WILL TRAVERSE ACROSS THE LOCAL AREA SUNDAY NIGHT AND EARLY MONDAY.
THE UPPER DYNAMICS WITH THIS SYSTEM ARE DECENT...BUT THE LOWER
PORTION OF THE ATMOSPHERE WILL REMAIN DRY...SO IT WILL BE
DIFFICULT TO GET MUCH MOISTURE TO THE SURFACE. THEREFORE...ONLY
SLIGHT CHANCE POPS ARE FORECAST WITH PRECIPITATION TYPE AS LIGHT
SNOW. TEMPERATURES WILL BE COOLER SUNDAY AND MONDAY...BUT STILL
ABOVE SEASONAL AVERAGES. AJZ
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
GFS AND EC MODELS GENERALLY AGREE THROUGH FRIDAY. FORECAST IS
FAIRLY DRY FOR THE LONG TERM WITH A SERIES OF PASSING SHORTWAVE
TROUGHS AND RIDGES. OUTSIDE CHANCE FOR A RAIN OR SNOW SHOWER
TUESDAY OR TUESDAY NIGHT AS A SOMEWHAT DRY CLIPPER-LIKE SYSTEM
DROPS INTO THE CENTRAL US. MOST SIGNIFICANT FEATURE IN THE LONG
TERM IS RIDGING WEDNESDAY INTO THURSDAY...WHICH SHOULD GIVE CLEAR
WEATHER AND ABOVE NORMAL TEMPERATURES FOR THANKSGIVING DAY.
RIDGE BREAKS DOWN WITH A SHARPER TROUGH IN THE EC MODEL...WHICH
SUGGESTS A HIGHER CHANCE FOR SOME SNOW ON SATURDAY THAN SEEN IN
THE GFS. MARTIN
PREVIOUS LONG TERM DISCUSSION...SHORTWAVE TROUGH DROPS SOUTHEAST
OUT OF SASKATCHEWAN DURING THE DAY TUESDAY AND MAY BRING A SLIGHT
CHANCE OF RAIN OR SNOW. THIS FAST MOVING SYSTEM WILL HAVE LIMITED
MOISTURE WITH IT.
AN UPPER RIDGE BUILDS INTO THE AREA ON WEDNESDAY AND WILL BRING
WARM AND DRY WEATHER THROUGH THANKSGIVING DAY FOR SURE.
MODELS HAVE SOME DIFFERENCES ON TRACK OF A SHORTWAVE THAT MOVES
INLAND FROM THE PACIFIC ON FRIDAY. ECMWF TAKES THE SYSTEM SOUTH OF
THE AREA WHILE THE GFS BRINGS IT ACROSS MONTANA. EITHER WAY...A
COLD FRONT WILL AFFECT THE FORECAST AREA ON FRIDAY WITH COOLER
TEMPERATURES EXPECTED NEXT WEEKEND. WILL KEEP THE FORECAST DRY FOR
THE MOST PART FOR NOW. FORRESTER
&&
.AVIATION...
VFR CONDITIONS. STRONG WEST WINDS THIS AFTERNOON SHOULD ABATE
AFTER SUNSET...DECREASING TO AROUND 10 KTS. WINDS TURN
SOUTHEASTERLY ON SUNDAY UP TO AROUND 15 KTS. MOSTLY CLEAR TO
SCATTERED SKIES ON SUNDAY WITH CEILINGS LOWERING OUT WEST SUNDAY
EVENING. MARTIN
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR FORT PECK
LAKE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 211751
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1040 AM MST SAT NOV 21 2009
AVIATION SECTION UPDATED
.UPDATE...
UPPER LEVEL TROUGH IS PROGRESSING ACROSS THE REGION THIS MORNING
WHILE THE ASSOCIATED PACIFIC COLD FRONT HAS MOVED THROUGH ALL ZONES
AND WILL CONTINUE TO PROGRESS EAST INTO THE DAKOTAS BY THIS
AFTERNOON. A PERIOD OF SNOW OCCURRED WITH THE FRONTAL PASSAGE
ACROSS MUCH OF SW MT EARLY THIS MORNING...WITH ONLY IMPACT ACROSS
NORTHERN ZONES BEING A SHIFT TO MORE WESTERLY WINDS. WINDS ALOFT
REMAIN FAIRLY STRONG AND COLD ADVECTION THROUGH TODAY WILL PROMOTE
MIXING OF THOSE STRONGER WINDS DOWN TO THE SURFACE ACROSS NORTHERN
ZONES THROUGH THIS AFTERNOON. STRONGEST WINDS WILL BE ALONG THE
NORTHERN ROCKY MTN FRONT AND GLACIER COUNTY...HOWEVER THE PERIOD
OF PEAK WINDS ALOFT HAS PASSED. STILL EXPECT SUSTAINED WINDS
NEAR 30KTS AT TIMES SO WILL LET THE HIGH WIND WARNING CONTINUE FOR
THOSE AREAS THROUGH THIS AFTERNOON. UNSTABLE AND SOMEWHAT MOIST
WESTERLY FLOW WILL MAINTAIN SCATTERED MTN SNOW SHOWERS THIS
AFTERNOON WITH MORE PERSISTENT SHOWER ACTIVITY EXPECTED OVER THE
GALLATIN/MADISON RANGES OF SW MT WHERE AN INCH OR TWO OF NEW SNOW
MAY FALL THROUGH THIS AFTERNOON. ELSEWHERE...DOWNSLOPE WESTERLY
FLOW WILL LIMIT PRECIPITATION CHANCES WITH PARTLY CLOUDY SKIES
ACROSS WESTERN PORTIONS OF NORTH CENTRAL MT. ONE EXCEPTION MAY BE
AREAS ALONG THE CANADIAN BORDER LATER THIS AFTERNOON AS A DISTURBANCE
DROPPING SE FROM ALBERTA MAY PRODUCE A FEW LIGHT SNOW SHOWERS OR
FLURRIES. HAVE MADE SOME MINOR ADJUSTMENTS TO POPS TO ACCOUNT FOR
THIS AND ALIGN WITH LATEST OBSERVATIONAL TRENDS. OTHERWISE...CURRENT
FORECAST IS IN GOOD SHAPE. HOENISCH
&&
.AVIATION...
UPDATED 1740Z.
AN UPPER LEVEL LOW PRESSURE TROUGH WILL CONTINUE TO MAKE ITS WAY
ACROSS CENTRAL MT THIS AFTN/EVE. MOST OF ASSOCIATED MOISTURE HAS
ALREADY PUSHED TOWARD KBIL BUT LOCATIONS WEST OF A KBIL-TO-KHLN LINE
WILL SEE A FEW RESIDUAL SNOWSHOWERS THROUGH MID-AFTN. CEILINGS
SHOULD REMAIN VFR ACROSS THE REGION...THOUGH HIGHER TERRAIN WILL BE
OBSCURED WITH MVFR/IFR CONDITIONS NEAR ANY PRECIPITATION AREAS.
WINDS WILL BE GUSTY OVER THE PLAINS AND ROCKY MTN FRONT THIS AFTN
WITH WIDESPREAD GUSTS OF 25 TO 35 KTS...AND SOME LOCATIONS FROM
GLACIER NP TO KHVR SEEING GUSTS OF 40 TO 50 KTS. AS THE TROUGH
MOVES FURTHER EAST THIS EVE...WINDS SHOULD DECREASE TOWARD SUNSET
AND SKIES WILL BE MOSTLY CLEAR OVERNIGHT AT ALL TERMINALS.
WARANAUSKAS
&&
.PREV DISCUSSION...
/ISSUED 510 AM MST SAT NOV 21 2009/
TODAY THROUGH MONDAY...PROGRESSIVE PATTERN WILL CONTINUE. ONE
UPPER TROUGH WILL MOVE THROUGH THE AREA TODAY INTO THIS EVENING. A
WEAK UPPER RIDGE WILL THEN MOVE OVER THE AREA BY LATE TONIGHT
BEFORE ANOTHER UPPER TROUGH MOVES THROUGH THE AREA SUNDAY NIGHT.
THEN THE NEXT UPPER RIDGE WILL APPROACH THE AREA LATE MONDAY. WITH
THE UPPER TROUGHS EXPECT SNOW OVER THE MOUNTAINS WITH A FAIR
CHANCE OF SOME SNOW IN THE SOUTHWEST VALLEYS. FOR EACH UPPER
TROUGH DO NOT SEE MORE THAN SIX INCHES OF SNOW IN THE MOUNTAINS
WHILE THE VALLEYS COULD RECEIVE UP TO AN INCH. ALTHOUGH DO NOT
PLAN ON ISSUING ANY WINTER WEATHER HIGHLIGHTS AT THIS POINT WILL
CONTINUE TO MENTION THE SNOW IN THE HAZARDOUS WEATHER OUTLOOK.
SPEAKING OF HIGHLIGHTS HAVE ISSUED A HIGH WIND WARNING FOR THE
NORTHERN ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS FOR TODAY. IT
APPEARS ATMOSPHERIC MIXING WILL BE ABLE TO TAP INTO 50 KNOT WINDS
JUST ABOVE THE SURFACE AT LEAST THIS MORNING. WITH THESE WEATHER
SYSTEMS DOWNSLOPE FLOW SHOULD KEEP THE PLAINS GENERALLY DRY. THE
SECOND UPPER TROUGH IS FORECAST TO HAVE MORE MOISTURE THAN THE
FIRST UPPER TROUGH SO WILL CONTINUE WITH THE MENTION OF A SLIGHT
CHANCE OF SNOW FOR LATE SUNDAY AND SUNDAY NIGHT. WITH THE UPPER
RIDGE APPROACHING ON MONDAY JUST EXPECT SOME LINGERING SNOW
SHOWERS OVER THE MOUNTAINS FROM SUNDAY NIGHTS SYSTEM. BLANK
MONDAY NIGHT THROUGH SATURDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT INTO THE MIDDLE OF NEXT WEEK. BOTH MODELS BRING A
WEAK SHORTWAVE TROUGH OVER AN UPPER LEVEL HIGH PRESSURE RIDGE PARKED
ALONG THE PACIFIC COAST THROUGH THE AREA MONDAY NIGHT INTO
TUESDAY...WHICH WILL BRING A CHANCE OF PRECIPITATION TO THE AREA.
THIS SHORTWAVE WILL ALSO BRING STRONG AND GUSTY WESTERLY DOWNSLOPE
WINDS TO THE AREA...WHICH WILL LIMIT PRECIPITATION OVER THE PLAINS
AND WARM TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE SEASONAL
AVERAGES. BOTH MODELS THEN AMPLIFY AND SHIFT THE UPPER RIDGE INTO
MONTANA TUESDAY NIGHT INTO THURSDAY. THIS RIDGE WILL KEEP THE AREA
WARM (TEMPERATURES 10 TO 15 DEGREES ABOVE NORMAL) AND MOSTLY DRY.
GUSTY WESTERLY SURFACE WINDS WILL INCREASE AGAIN WEDNESDAY NIGHT
INTO THURSDAY (THANKSGIVING DAY) AS THE NEXT SYSTEM APPROACHES THE
AREA. THE MODELS BEGIN TO DIFFER ON THURSDAY. UNLIKE THE MODEL RUNS
FROM LAST NIGHT...THE ECMWF BRINGS THE NEXT PACIFIC SYSTEM THROUGH
THE STATE QUICKER THAN THE GFS. WITH THIS UNCERTAINTY...HAVE KEPT
NEAR CLIMATOLOGICAL CHANCES OF PRECIPITATION OVER THE TFX CWA FRIDAY
THROUGH SATURDAY...WITH TEMPERATURES COOLING TO NEAR SEASONAL
NORMALS BY SATURDAY. AN UPPER LEVEL RIDGE THEN BEGINS TO MOVE INTO
THE WESTERN UNITED STATES SATURDAY NIGHT...WHICH SHOULD CAUSE THE
CHANCE FOR PRECIPITATION TO DECREASE. UPPER LEVEL SUPPORT FOR THE
INCREASING WINDS THROUGH THIS PERIOD IS TEMPORARY. THEREFORE...AM
NOT ANTICIPATING HIGH WIND HIGHLIGHTS AT THIS TIME AND WILL NOT
MENTION IN THE HAZARDOUS WEATHER OUTLOOK. HOWEVER...THE POTENTIAL
FOR BRIEF PERIODS OF STRONG WINDS STILL REMAINS...AND THE SITUATION
WILL CONTINUE TO BE MONITORED. COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 44 25 41 27 / 10 0 20 20
CTB 42 23 39 26 / 0 0 20 20
HLN 43 23 41 26 / 20 0 30 30
BZN 37 13 37 16 / 50 0 30 40
WEY 31 8 30 12 / 90 30 80 60
DLN 34 14 34 13 / 40 0 40 40
HVR 48 19 45 25 / 20 10 10 10
LWT 43 18 38 21 / 10 0 10 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 5 PM MST THIS AFTERNOON FOR MTZ009-010.
&&
$$
SHORT TERM...BLANK
LONG TERM...COULSTON
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 211646
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
946 AM MST SAT NOV 21 2009
.UPDATE...
UPPER LEVEL TROUGH IS PROGRESSING ACROSS THE REGION THIS MORNING
WHILE THE ASSOCIATED PACIFIC COLD FRONT HAS MOVED THROUGH ALL ZONES
AND WILL CONTINUE TO PROGRESS EAST INTO THE DAKOTAS BY THIS
AFTERNOON. A PERIOD OF SNOW OCCURRED WITH THE FRONTAL PASSAGE
ACROSS MUCH OF SW MT EARLY THIS MORNING...WITH ONLY IMPACT ACROSS
NORTHERN ZONES BEING A SHIFT TO MORE WESTERLY WINDS. WINDS ALOFT
REMAIN FAIRLY STRONG AND COLD ADVECTION THROUGH TODAY WILL PROMOTE
MIXING OF THOSE STRONGER WINDS DOWN TO THE SURFACE ACROSS NORTHERN
ZONES THROUGH THIS AFTERNOON. STRONGEST WINDS WILL BE ALONG THE
NORTHERN ROCKY MTN FRONT AND GLACIER COUNTY...HOWEVER THE PERIOD
OF PEAK WINDS ALOFT HAS PASSED. STILL EXPECT SUSTAINED WINDS
NEAR 30KTS AT TIMES SO WILL LET THE HIGH WIND WARNING CONTINUE FOR
THOSE AREAS THROUGH THIS AFTERNOON. UNSTABLE AND SOMEWHAT MOIST
WESTERLY FLOW WILL MAINTAIN SCATTERED MTN SNOW SHOWERS THIS
AFTERNOON WITH MORE PERSISTENT SHOWER ACTIVITY EXPECTED OVER THE
GALLATIN/MADISON RANGES OF SW MT WHERE AN INCH OR TWO OF NEW SNOW
MAY FALL THROUGH THIS AFTERNOON. ELSEWHERE...DOWNSLOPE WESTERLY
FLOW WILL LIMIT PRECIPITATION CHANCES WITH PARTLY CLOUDY SKIES
ACROSS WESTERN PORTIONS OF NORTH CENTRAL MT. ONE EXCEPTION MAY BE
AREAS ALONG THE CANADIAN BORDER LATER THIS AFTERNOON AS A DISTURBANCE
DROPING SE FROM ALBERTA MAY PRODUCE A FEW LIGHT SNOW SHOWERS OR
FLURRIES. HAVE MADE SOME MINOR ADJUSTMENTS TO POPS TO ACCOUNT FOR
THIS AND ALIGN WITH LATEST OBSERVATIONAL TRENDS. OTHERWISE...CURRENT
FORECAST IS IN GOOD SHAPE. HOENISCH
&&
.AVIATION...
UPDATED 1210Z.
AN UPPER LEVEL LOW PRESSURE TROUGH OVER THE PACIFIC NORTHWEST WILL
CONTINUE TO OBSCURE THE MOUNTAIN AREAS OF WESTERN...SOUTHWEST...AND
CENTRAL MONTANA IN CLOUDS AND SNOW SHOWERS THIS MORNING. THE KHLN
TERMINAL MAY ALSO LOWER TO MVFR CONDITIONS IN RAIN/SNOW SHOWERS AT
TIMES THIS MORNING...WHILE LOCAL UPSLOPE CONDITIONS AT KBZN WILL
LOWER CONDITIONS TO IFR LEVELS AT TIMES DUE TO HEAVIER SNOW SHOWERS.
PRECIPITATION WILL DECREASE DURING THE AFTERNOON AS THE UPPER TROUGH
MOVES INTO THE AREA. GUSTY WESTERLY WINDS WILL ALSO INCREASE
SIGNIFICANTLY THIS MORNING AS AN ASSOCIATED COLD FRONT MOVES EAST
ACROSS THE AREA. WINDS WILL BE ESPECIALLY STRONG ALONG THE EAST
SLOPES OF THE ROCKIES...WHERE GUSTS COULD REACH 50 KT AT TIMES.
HOWEVER...THE DOWNSLOPE EFFECT OF THE WINDS OVER THE PLAINS OF NORTH
CENTRAL AND CENTRAL MONTANA WILL LIMIT PRECIPITATION TO AN ISOLATED
SHOWER OR TWO AT BEST THERE. AN UPPER LEVEL RIDGE OF HIGH PRESSURE
WILL THEN MOVE INTO THE AREA AFTER 00Z SUNDAY FOR CLEARING SKIES AND
DECREASING WINDS OVERNIGHT. COULSTON
&&
.PREV DISCUSSION...
/ISSUED 510 AM MST SAT NOV 21 2009/
TODAY THROUGH MONDAY...PROGRESSIVE PATTERN WILL CONTINUE. ONE
UPPER TROUGH WILL MOVE THROUGH THE AREA TODAY INTO THIS EVENING. A
WEAK UPPER RIDGE WILL THEN MOVE OVER THE AREA BY LATE TONIGHT
BEFORE ANOTHER UPPER TROUGH MOVES THROUGH THE AREA SUNDAY NIGHT.
THEN THE NEXT UPPER RIDGE WILL APPROACH THE AREA LATE MONDAY. WITH
THE UPPER TROUGHS EXPECT SNOW OVER THE MOUNTAINS WITH A FAIR
CHANCE OF SOME SNOW IN THE SOUTHWEST VALLEYS. FOR EACH UPPER
TROUGH DO NOT SEE MORE THAN SIX INCHES OF SNOW IN THE MOUNTAINS
WHILE THE VALLEYS COULD RECEIVE UP TO AN INCH. ALTHOUGH DO NOT
PLAN ON ISSUING ANY WINTER WEATHER HIGHLIGHTS AT THIS POINT WILL
CONTINUE TO MENTION THE SNOW IN THE HAZARDOUS WEATHER OUTLOOK.
SPEAKING OF HIGHLIGHTS HAVE ISSUED A HIGH WIND WARNING FOR THE
NORTHERN ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS FOR TODAY. IT
APPEARS ATMOSPHERIC MIXING WILL BE ABLE TO TAP INTO 50 KNOT WINDS
JUST ABOVE THE SURFACE AT LEAST THIS MORNING. WITH THESE WEATHER
SYSTEMS DOWNSLOPE FLOW SHOULD KEEP THE PLAINS GENERALLY DRY. THE
SECOND UPPER TROUGH IS FORECAST TO HAVE MORE MOISTURE THAN THE
FIRST UPPER TROUGH SO WILL CONTINUE WITH THE MENTION OF A SLIGHT
CHANCE OF SNOW FOR LATE SUNDAY AND SUNDAY NIGHT. WITH THE UPPER
RIDGE APPROACHING ON MONDAY JUST EXPECT SOME LINGERING SNOW
SHOWERS OVER THE MOUNTAINS FROM SUNDAY NIGHTS SYSTEM. BLANK
MONDAY NIGHT THROUGH SATURDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT INTO THE MIDDLE OF NEXT WEEK. BOTH MODELS BRING A
WEAK SHORTWAVE TROUGH OVER AN UPPER LEVEL HIGH PRESSURE RIDGE PARKED
ALONG THE PACIFIC COAST THROUGH THE AREA MONDAY NIGHT INTO
TUESDAY...WHICH WILL BRING A CHANCE OF PRECIPITATION TO THE AREA.
THIS SHORTWAVE WILL ALSO BRING STRONG AND GUSTY WESTERLY DOWNSLOPE
WINDS TO THE AREA...WHICH WILL LIMIT PRECIPITATION OVER THE PLAINS
AND WARM TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE SEASONAL
AVERAGES. BOTH MODELS THEN AMPLIFY AND SHIFT THE UPPER RIDGE INTO
MONTANA TUESDAY NIGHT INTO THURSDAY. THIS RIDGE WILL KEEP THE AREA
WARM (TEMPERATURES 10 TO 15 DEGREES ABOVE NORMAL) AND MOSTLY DRY.
GUSTY WESTERLY SURFACE WINDS WILL INCREASE AGAIN WEDNESDAY NIGHT
INTO THURSDAY (THANKSGIVING DAY) AS THE NEXT SYSTEM APPROACHES THE
AREA. THE MODELS BEGIN TO DIFFER ON THURSDAY. UNLIKE THE MODEL RUNS
FROM LAST NIGHT...THE ECMWF BRINGS THE NEXT PACIFIC SYSTEM THROUGH
THE STATE QUICKER THAN THE GFS. WITH THIS UNCERTAINTY...HAVE KEPT
NEAR CLIMATOLOGICAL CHANCES OF PRECIPITATION OVER THE TFX CWA FRIDAY
THROUGH SATURDAY...WITH TEMPERATURES COOLING TO NEAR SEASONAL
NORMALS BY SATURDAY. AN UPPER LEVEL RIDGE THEN BEGINS TO MOVE INTO
THE WESTERN UNITED STATES SATURDAY NIGHT...WHICH SHOULD CAUSE THE
CHANCE FOR PRECIPITATION TO DECREASE. UPPER LEVEL SUPPORT FOR THE
INCREASING WINDS THROUGH THIS PERIOD IS TEMPORARY. THEREFORE...AM
NOT ANTICIPATING HIGH WIND HIGHLIGHTS AT THIS TIME AND WILL NOT
MENTION IN THE HAZARDOUS WEATHER OUTLOOK. HOWEVER...THE POTENTIAL
FOR BRIEF PERIODS OF STRONG WINDS STILL REMAINS...AND THE SITUATION
WILL CONTINUE TO BE MONITORED. COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 44 25 41 27 / 10 0 20 20
CTB 42 23 39 26 / 0 0 20 20
HLN 43 23 41 26 / 20 0 30 30
BZN 37 13 37 16 / 50 0 30 40
WEY 31 8 30 12 / 90 30 80 60
DLN 34 14 34 13 / 40 0 40 40
HVR 48 19 45 25 / 20 10 10 10
LWT 43 18 38 21 / 10 0 10 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 5 PM MST THIS AFTERNOON FOR MTZ009-010.
&&
$$
SHORT TERM...BLANK
LONG TERM...COULSTON
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KGGW 211627 AAA
AFDGGW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
927 AM MST SAT NOV 21 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...
A VIGOROUS PACIFIC TROUGH AND COLD FRONT ARE IN THE PROCESS OF
CROSSING NORTHEAST MONTANA THIS MORNING. A STRONG WEST WIND IS
DEVELOPING IN THE WAKE OF THE FRONT WITH THE WESTERN ZONES
BEGINNING TO EXPERIENCE WIND SPEEDS IN EXCESS OF 20 MPH...WITH
GUSTS ABOVE 30 MPH. THE WIND SHOULD INCREASE ACROSS THE ENTIRE
AREA TODAY WITH COLD AIR ADVECTION AND STRONG SUBSIDENCE BEHIND
THE TROUGH. THE CURRENT LAKE WIND ADVISORY AND ITS TIME DURATION
REMAIN REASONABLE. OVERNIGHT RELATIVE HUMIDITY RECOVERY AHEAD OF
THE FRONT WAS VERY POOR IN THE LITTLE ROCKIES AND MISSOURI BREAKS
REGION. HOWEVER...DEWPOINTS ARE INCREASING...AND TEMPERATURES ARE
FALLING SLIGHTLY HENCE RELATIVE HUMIDITY IS RECOVERING THIS
MORNING. A BRIEF PERIOD OF LOW RELATIVE HUMIDITY IS STILL EXPECTED
THIS AFTERNOON...BUT THE MORNING RECOVERY SHOULD PRECLUDE ANY FIRE
WEATHER HIGHLIGHTS. THE OVERALL FORECAST IS IN GOOD SHAPE AND THE
PRIMARY UPDATE INVOLVED BLENDING OVERNIGHT RELATIVE HUMIDITY
PERCENTAGES TO FORECAST VALUES IN ORDER TO DIAGNOSE WHETHER A
FIRE WEATHER HIGHLIGHT WAS NECESSARY OR NOT. AJZ
PREVIOUS SHORT TERM DISCUSSION...
AN ENERGETIC SHORT WAVE TROUGH AND COLD FRONT SWEEP OVER THE
ZONES TODAY. THE MAIN EFFECT WILL BE STRONG WINDS WESTERLY WINDS
BEHIND THE FRONT. A STRONG SURFACE TROUGH ANCHORED BY A LOW
CENTERED IN SOUTHERN SASKATCHEWAN WILL MAINTAIN A STRONG PRESSURE
GRADIENT ACROSS THE SURFACE. THESE WINDS WILL BE REINFORCED BY
850MB WINDS OF 35-40KTS RESULTING IN SURFACE WIND GUSTS OF EQUAL
STRENGTH. THE LWA SEEMS LIKE A SLAM-DUNK SO WILL RENEW THE NPW
DURING THIS PACKAGE. MOISTURE IS RATHER ANEMIC WITH THIS SYSTEM SO
EXPECT MOSTLY CLOUD COVER WITH LITTLE PRECIPITATION. A VORT MAX
AROUND THE BASE OF THE UPPER LEVEL TROUGH COULD PRODUCE SOME
MOISTURE IN SOUTHERN ALBERTA/SASKATCHEWAN THAT MIGHT SPREAD A BIT
ACROSS THE INTERNATIONAL BORDER. SO WILL MAINTAIN POPS JUST BELOW
TEXT MENTION FOR NOW. THE OTHER PREVIOUSLY MENTIONED CONCERN WAS
THE EXPECTED LOW RH VALUES FOR TODAY WHICH COULD PRODUCE NEAR
CRITICAL FIRE WEATHER CONDITIONS. SEE FIRE WX SEPARATE DISCUSSION
BELOW.
TONIGHT/SUNDAY...UPPER FLOW VEERS TO THE NORTHWEST LATE TONIGHT AS
THE UPPER TROUGH BASE MOVES EAST. A SHORT WAVE UPPER RIDGE FOLLOWS
BUT IS QUICKLY FOLLOWED BY THE NEXT SHORT WAVE TROUGH. THIS NEXT
WAVE SENDS A WEAK COLD FRONT INTO THE CWA BY AFTERNOON WHICH COULD
PRODUCE LIGHT PRECIPITATION OVER THE WESTERN ZONES. 850MB
TEMPERATURES REMAIN NEAR 0*C OR JUST BELOW SO MIXED PRECIPITATION
IS A POSSIBILITY. WITH THE ATMOSPHERE DECOUPLING AT SUNSET...THE
RELAXING GRADIENT WILL ALLOW WINDS TO DROP BELOW LWA CRITERIA.
SUNDAY NIGHT/MONDAY...THE BASE OF THE TROUGH DROPS SOUTH INTO
NORTHERN COLORADO...TAKING MOST OF THE ENERGY TO OUR SOUTH.
HOWEVER THE INVERTED SURFACE EXTENDS NORTH INTO NORTHEASTERN
MONTANA WHICH WILL KEEP CONDITIONS A BIT UNSETTLED. WHILE
NAM...UKMET AND EC STAY DRY...BASED ON GFS...GEM AND SREF...SLIGHT
CHANCE POPS SEEM APPROPRIATE FOR SNOW OVERNIGHT. CONDITIONS DO
NOT CHANGE MUCH FOR MONDAY SO WILL KEEP SLIGHT CHANCE POPS GOING.
SURFACE HIGHS WILL DROP DOWN MUCH CLOSER TO NORMAL WHILE 850MB
TEMPERATURES HOVER AROUND -4*C. SO EXPECT ANY PRECIPITATION TO
FALL AS SNOW AND POSSIBLY RAIN SHOWERS. QPF AMOUNTS WILL NOT
PRODUCE ACCUMULATIONS. SCT
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
SHORTWAVE TROUGH DROPS SOUTHEAST OUT OF SASKATCHEWAN DURING THE
DAY TUESDAY AND MAY BRING A SLIGHT CHANCE OF RAIN OR SNOW. THIS
FAST MOVING SYSTEM WILL HAVE LIMITED MOISTURE WITH IT.
AN UPPER RIDGE BUILDS INTO THE AREA ON WEDNESDAY AND WILL BRING
WARM AND DRY WEATHER THROUGH THANKSGIVING DAY FOR SURE.
MODELS HAVE SOME DIFFERENCES ON TRACK OF A SHORTWAVE THAT MOVES
INLAND FROM THE PACIFIC ON FRIDAY. ECMWF TAKES THE SYSTEM SOUTH OF
THE AREA WHILE THE GFS BRINGS IT ACROSS MONTANA. EITHER WAY...A
COLD FRONT WILL AFFECT THE FORECAST AREA ON FRIDAY WITH COOLER
TEMPERATURES EXPECTED NEXT WEEKEND. WILL KEEP THE FORECAST DRY FOR
THE MOST PART FOR NOW. FORRESTER
&&
.AVIATION...
VFR CONDITIONS. A MIX OF MID AND HIGH LEVEL CLOUDS WILL MOVE
THROUGH THE AREA TODAY WITH CEILINGS ABOVE 10 000 FT AND NO
OBSTRUCTIONS TO VISIBILITY. SKIES CLEARING TONIGHT. WEST WINDS
THIS MORNING WILL INCREASE TO 20 TO 25 KNOTS BY 18Z WITH HIGHER
GUSTS. THE WINDS WILL DIMINISH TO AROUND 10 KTS AFTER SUNSET.
&&
.FIRE WEATHER...
A STRONG WEST WIND WILL DEVELOP TODAY BEHIND A COLD FRONT. WIND
SPEEDS ARE EXPECTED TO REACH 20 TO 30 MPH...WITH GUSTS TO 40 MPH
DURING THE LATE MORNING AND AFTERNOON HOURS. AFTERNOON MINIMUM
RELATIVE HUMIDITY VALUES ARE EXPECTED TO BRIEFLY DROP INTO THE 20
TO 30 PERCENT RANGE BEFORE BEGINNING A STEADY RECOVERY NEAR
SUNSET. THEREFORE...A BRIEF PERIOD OF CRITICAL FIRE WEATHER
CONDITIONS ARE POSSIBLE THIS AFTERNOON...BUT HIGHLIGHTS ARE NOT
EXPECTED AT THIS TIME DUE TO THE SHORT DURATION OF LOW RELATIVE
HUMIDITY DUE TO SHORTENING SUNLIGHT HOURS. THE MOST SUSCEPTIBLE
AREAS WILL BE THE LITTLE ROCKY MOUNTAINS AND THE MISSOURI BREAKS
REGION OF ZONES 119 AND 121...WHICH EXPERIENCED A RATHER POOR
RELATIVE HUMIDITY RECOVERY LAST NIGHT. AJZ/SCT
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR FORT PECK
LAKE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 211537
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
837 AM MST SAT NOV 21 2009
.SHORT TERM...VALID FOR TDY AND SUN...
COLD FRONT MOVING ACROSS THE REGION THIS MORNING WITH
PRECIPITATION LIMITED TO THE MOUNTAINS AS DOWNSLOPE IS HAVING A
BIG IMPACT ON PLAINS. BIGGER STORY IS WINDS ACROSS THE REGION AS
THEY ARE A MIX OF MOMENTUM MIX DOWN...PRESSURE RISES AND
GRADIENTS...AND EVAPORTIVE COOLING FROM DYING SHOWERS. HAVE
UPDATED FORECASTS TO INDICATE STRONGER WINDS AND SPECIFICALLY A
TENDENCY FOR WINDS TO BE GUSTY IN NATURE. ALSO...DECREASED
PRECIPITATION CHANCES ACROSS MOST OF THE PLAINS TO SPRINKLES.
TEMPERATURES A DIFFERENT CHALLENGE AS PROBABLY WILL BE COOLING IN
THE WEST WHILE STILL WARMING A BIT IN THE EAST FOR A COUPLE OF HOURS.
UPDATES ALREADY SENT. WINDS WILL DECREASE THIS EVENING AND IT
SHOULD BE A MUCH COOLER NIGHT. BORSUM
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
A PROGRESSIVE PATTERN DEVELOPS OVER THE FORECAST AREA FOR THE
EXTENDED. 3 SYSTEMS WILL IMPACT THE AREA NEXT WEEK...BUT
RIDGING ON THANKSGIVING BRINGS WARM...DRY AND BREEZY CONDITIONS TO
THE AREA. THE FIRST SYSTEM IS OVER THE AREA MONDAY...SHIFTING
SOUTHEAST MONDAY NIGHT. INCREASED POPS OVER EASTERN AREAS MONDAY
AS WELL AS KEEPING SOME POPS FOR WESTERN MOUNTAIN AND FOOTHILLS
LOCATIONS. TEMPERATURES DON`T LOOK TERRIBLY COLD WITH THIS SYSTEM
IN THE LOWER 40S...AND COULD BE A TAD COOLER IN SOME LOCATIONS
WHERE CLOUDS AND PRECIPITATION OCCUR. AN ALBERTA CLIPPER SYSTEM
QUICKLY MOVES THROUGH EASTERN AREAS ON TUESDAY AFTERNOON...THOUGH
NOT BEFORE TEMPERATURES CLIMB INTO THE LOW TO MID 40S. IF TIMING
OF THE CLIPPER IS FASTER WILL NEED TO COOL EASTERN AREAS 5 TO 10
DEGREES. RIDGING BUILDS INTO THE AREA WEDNESDAY AND THURSDAY WITH
DOWNSLOPE WIND GRADIENT IN PLACE PUSHING TEMPERATURES BACK INTO
THE 50S. THE FINAL SYSTEM ARRIVES FRIDAY OR SATURDAY DEPENDING ON
MODEL PREFERENCE. THE ECMWF DIGS THE LATE WEEK SYSTEM FURTHER TO
THE SOUTH AND BRINGS COOLER AIR INTO THE AREA FRIDAY
AFTERNOON...WHILE THE GFS IS LESS DEEP WITH THE SYSTEM KEEPING THE
ENERGY OVER MONTANA AND WYOMING AND BRINGS COLDER AIR IN FOR
SATURDAY. 00Z ENSEMBLE DATA SUPPORTIVE OF THE OPERATIONAL GFS
KEEPING TROF FURTHER NORTH...AND TRENDED FORECAST TOWARD THE GFS
FOR THE LATER PERIODS...INCLUDING INCREASING POPS AND LOWERING
TEMPERATURES JUST A TAD. CHAMBERS
&&
.AVIATION...
COLD FRONT WILL CONTINUE TO MOVE ACROSS THE AREA THIS MORNING
BRINGING GUSTY WINDS UP TO 40 KNOTS. GUSTY WINDS UP TO 30 KNOTS
WILL CONTINUE BEHIND THE FRONT THROUGH EARLY EVENING. MVFR
CONDITIONS AND MOUNTAIN OBSCURATIONS WILL BE POSSIBLE THROUGH THE
DAY ACROSS THE WESTERN ROUTES...INCLUDING THE KLVM AREA ...WHERE
SCATTERED SNOW SHOWERS WILL CONTINUE. ACROSS THE OTHER
AREAS...SPRINKLES WILL BE POSSIBLE WITH VFR CONDITIONS
PREVAILING. SOLUM
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 048 023/040 028/042 024/046 030/051 036/055 035/051
1/N 02/W 21/B 11/B 00/B 00/U 02/W
LVM 041 020/036 020/035 018/043 025/050 029/054 031/046
4/W 04/J 32/J 12/W 10/B 00/B 03/W
HDN 051 024/043 024/044 019/047 025/052 031/057 030/053
1/M 02/W 22/W 12/W 00/B 00/U 02/W
MLS 053 022/045 024/043 020/047 023/046 030/056 031/051
1/N 02/W 22/W 22/W 10/B 00/U 01/U
4BQ 051 023/042 021/042 019/045 022/046 028/056 029/051
1/N 22/W 22/J 12/W 00/B 00/U 01/U
BHK 053 021/045 021/040 019/043 020/040 024/054 027/051
1/N 11/B 22/J 22/W 10/B 00/U 01/U
SHR 047 020/043 022/039 014/046 024/050 028/056 028/051
2/W 22/W 22/J 11/B 00/B 00/U 01/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 211210
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
510 AM MST SAT NOV 21 2009
...UPDATE TO AVIATION...
.DISCUSSION...
TODAY THROUGH MONDAY...PROGRESSIVE PATTERN WILL CONTINUE. ONE
UPPER TROUGH WILL MOVE THROUGH THE AREA TODAY INTO THIS EVENING. A
WEAK UPPER RIDGE WILL THEN MOVE OVER THE AREA BY LATE TONIGHT
BEFORE ANOTHER UPPER TROUGH MOVES THROUGH THE AREA SUNDAY NIGHT.
THEN THE NEXT UPPER RIDGE WILL APPROACH THE AREA LATE MONDAY. WITH
THE UPPER TROUGHS EXPECT SNOW OVER THE MOUNTAINS WITH A FAIR
CHANCE OF SOME SNOW IN THE SOUTHWEST VALLEYS. FOR EACH UPPER
TROUGH DO NOT SEE MORE THAN SIX INCHES OF SNOW IN THE MOUNTAINS
WHILE THE VALLEYS COULD RECEIVE UP TO AN INCH. ALTHOUGH DO NOT
PLAN ON ISSUING ANY WINTER WEATHER HIGHLIGHTS AT THIS POINT WILL
CONTINUE TO MENTION THE SNOW IN THE HAZARDOUS WEATHER OUTLOOK.
SPEAKING OF HIGHLIGHTS HAVE ISSUED A HIGH WIND WARNING FOR THE
NORTHERN ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS FOR TODAY. IT
APPEARS ATMOSPHERIC MIXING WILL BE ABLE TO TAP INTO 50 KNOT WINDS
JUST ABOVE THE SURFACE AT LEAST THIS MORNING. WITH THESE WEATHER
SYSTEMS DOWNSLOPE FLOW SHOULD KEEP THE PLAINS GENERALLY DRY. THE
SECOND UPPER TROUGH IS FORECAST TO HAVE MORE MOISTURE THAN THE
FIRST UPPER TROUGH SO WILL CONTINUE WITH THE MENTION OF A SLIGHT
CHANCE OF SNOW FOR LATE SUNDAY AND SUNDAY NIGHT. WITH THE UPPER
RIDGE APPROACHING ON MONDAY JUST EXPECT SOME LINGERING SNOW
SHOWERS OVER THE MOUNTAINS FROM SUNDAY NIGHTS SYSTEM. BLANK
MONDAY NIGHT THROUGH SATURDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT INTO THE MIDDLE OF NEXT WEEK. BOTH MODELS BRING A
WEAK SHORTWAVE TROUGH OVER AN UPPER LEVEL HIGH PRESSURE RIDGE PARKED
ALONG THE PACIFIC COAST THROUGH THE AREA MONDAY NIGHT INTO
TUESDAY...WHICH WILL BRING A CHANCE OF PRECIPITATION TO THE AREA.
THIS SHORTWAVE WILL ALSO BRING STRONG AND GUSTY WESTERLY DOWNSLOPE
WINDS TO THE AREA...WHICH WILL LIMIT PRECIPITATION OVER THE PLAINS
AND WARM TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE SEASONAL
AVERAGES. BOTH MODELS THEN AMPLIFY AND SHIFT THE UPPER RIDGE INTO
MONTANA TUESDAY NIGHT INTO THURSDAY. THIS RIDGE WILL KEEP THE AREA
WARM (TEMPERATURES 10 TO 15 DEGREES ABOVE NORMAL) AND MOSTLY DRY.
GUSTY WESTERLY SURFACE WINDS WILL INCREASE AGAIN WEDNESDAY NIGHT
INTO THURSDAY (THANKSGIVING DAY) AS THE NEXT SYSTEM APPROACHES THE
AREA. THE MODELS BEGIN TO DIFFER ON THURSDAY. UNLIKE THE MODEL RUNS
FROM LAST NIGHT...THE ECMWF BRINGS THE NEXT PACIFIC SYSTEM THROUGH
THE STATE QUICKER THAN THE GFS. WITH THIS UNCERTAINTY...HAVE KEPT
NEAR CLIMATOLOGICAL CHANCES OF PRECIPITATION OVER THE TFX CWA FRIDAY
THROUGH SATURDAY...WITH TEMPERATURES COOLING TO NEAR SEASONAL
NORMALS BY SATURDAY. AN UPPER LEVEL RIDGE THEN BEGINS TO MOVE INTO
THE WESTERN UNITED STATES SATURDAY NIGHT...WHICH SHOULD CAUSE THE
CHANCE FOR PRECIPITATION TO DECREASE. UPPER LEVEL SUPPORT FOR THE
INCREASING WINDS THROUGH THIS PERIOD IS TEMPORARY. THEREFORE...AM
NOT ANTICIPATING HIGH WIND HIGHLIGHTS AT THIS TIME AND WILL NOT
MENTION IN THE HAZARDOUS WEATHER OUTLOOK. HOWEVER...THE POTENTIAL
FOR BRIEF PERIODS OF STRONG WINDS STILL REMAINS...AND THE SITUATION
WILL CONTINUE TO BE MONITORED. COULSTON
&&
.AVIATION...
UPDATED 1210Z.
AN UPPER LEVEL LOW PRESSURE TROUGH OVER THE PACIFIC NORTHWEST WILL
CONTINUE TO OBSCURE THE MOUNTAIN AREAS OF WESTERN...SOUTHWEST...AND
CENTRAL MONTANA IN CLOUDS AND SNOW SHOWERS THIS MORNING. THE KHLN
TERMINAL MAY ALSO LOWER TO MVFR CONDITIONS IN RAIN/SNOW SHOWERS AT
TIMES THIS MORNING...WHILE LOCAL UPSLOPE CONDITIONS AT KBZN WILL
LOWER CONDITIONS TO IFR LEVELS AT TIMES DUE TO HEAVIER SNOW SHOWERS.
PRECIPITATION WILL DECREASE DURING THE AFTERNOON AS THE UPPER TROUGH
MOVES INTO THE AREA. GUSTY WESTERLY WINDS WILL ALSO INCREASE
SIGNIFICANTLY THIS MORNING AS AN ASSOCIATED COLD FRONT MOVES EAST
ACROSS THE AREA. WINDS WILL BE ESPECIALLY STRONG ALONG THE EAST
SLOPES OF THE ROCKIES...WHERE GUSTS COULD REACH 50 KT AT TIMES.
HOWEVER...THE DOWNSLOPE EFFECT OF THE WINDS OVER THE PLAINS OF NORTH
CENTRAL AND CENTRAL MONTANA WILL LIMIT PRECIPITATION TO AN ISOLATED
SHOWER OR TWO AT BEST THERE. AN UPPER LEVEL RIDGE OF HIGH PRESSURE
WILL THEN MOVE INTO THE AREA AFTER 00Z SUNDAY FOR CLEARING SKIES AND
DECREASING WINDS OVERNIGHT. COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 44 25 41 27 / 10 0 20 20
CTB 42 23 39 26 / 10 0 20 20
HLN 43 23 41 26 / 20 0 30 30
BZN 37 13 37 16 / 50 0 30 40
WEY 31 8 30 12 / 90 30 80 60
DLN 34 14 34 13 / 50 0 40 40
HVR 48 19 45 25 / 10 10 10 10
LWT 43 18 38 21 / 10 0 10 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 5 PM MST THIS AFTERNOON FOR MTZ009-010.
&&
$$
SHORT TERM...BLANK
LONG TERM...COULSTON
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 211058
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
358 AM MST SAT NOV 21 2009
.DISCUSSION...
TODAY THROUGH MONDAY...PROGRESSIVE PATTERN WILL CONTINUE. ONE
UPPER TROUGH WILL MOVE THROUGH THE AREA TODAY INTO THIS EVENING. A
WEAK UPPER RIDGE WILL THEN MOVE OVER THE AREA BY LATE TONIGHT
BEFORE ANOTHER UPPER TROUGH MOVES THROUGH THE AREA SUNDAY NIGHT.
THEN THE NEXT UPPER RIDGE WILL APPROACH THE AREA LATE MONDAY. WITH
THE UPPER TROUGHS EXPECT SNOW OVER THE MOUNTAINS WITH A FAIR
CHANCE OF SOME SNOW IN THE SOUTHWEST VALLEYS. FOR EACH UPPER
TROUGH DO NOT SEE MORE THAN SIX INCHES OF SNOW IN THE MOUNTAINS
WHILE THE VALLEYS COULD RECEIVE UP TO AN INCH. ALTHOUGH DO NOT
PLAN ON ISSUING ANY WINTER WEATHER HIGHLIGHTS AT THIS POINT WILL
CONTINUE TO MENTION THE SNOW IN THE HAZARDOUS WEATHER OUTLOOK.
SPEAKING OF HIGHLIGHTS HAVE ISSUED A HIGH WIND WARNING FOR THE
NORTHERN ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS FOR TODAY. IT
APPEARS ATMOSPHERIC MIXING WILL BE ABLE TO TAP INTO 50 KNOT WINDS
JUST ABOVE THE SURFACE AT LEAST THIS MORNING. WITH THESE WEATHER
SYSTEMS DOWNSLOPE FLOW SHOULD KEEP THE PLAINS GENERALLY DRY. THE
SECOND UPPER TROUGH IS FORECAST TO HAVE MORE MOISTURE THAN THE
FIRST UPPER TROUGH SO WILL CONTINUE WITH THE MENTION OF A SLIGHT
CHANCE OF SNOW FOR LATE SUNDAY AND SUNDAY NIGHT. WITH THE UPPER
RIDGE APPROACHING ON MONDAY JUST EXPECT SOME LINGERING SNOW
SHOWERS OVER THE MOUNTAINS FROM SUNDAY NIGHTS SYSTEM. BLANK
MONDAY NIGHT THROUGH SATURDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT INTO THE MIDDLE OF NEXT WEEK. BOTH MODELS BRING A
WEAK SHORTWAVE TROUGH OVER AN UPPER LEVEL HIGH PRESSURE RIDGE PARKED
ALONG THE PACIFIC COAST THROUGH THE AREA MONDAY NIGHT INTO
TUESDAY...WHICH WILL BRING A CHANCE OF PRECIPITATION TO THE AREA.
THIS SHORTWAVE WILL ALSO BRING STRONG AND GUSTY WESTERLY DOWNSLOPE
WINDS TO THE AREA...WHICH WILL LIMIT PRECIPITATION OVER THE PLAINS
AND WARM TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE SEASONAL
AVERAGES. BOTH MODELS THEN AMPLIFY AND SHIFT THE UPPER RIDGE INTO
MONTANA TUESDAY NIGHT INTO THURSDAY. THIS RIDGE WILL KEEP THE AREA
WARM (TEMPERATURES 10 TO 15 DEGREES ABOVE NORMAL) AND MOSTLY DRY.
GUSTY WESTERLY SURFACE WINDS WILL INCREASE AGAIN WEDNESDAY NIGHT
INTO THURSDAY (THANKSGIVING DAY) AS THE NEXT SYSTEM APPROACHES THE
AREA. THE MODELS BEGIN TO DIFFER ON THURSDAY. UNLIKE THE MODEL RUNS
FROM LAST NIGHT...THE ECMWF BRINGS THE NEXT PACIFIC SYSTEM THROUGH
THE STATE QUICKER THAN THE GFS. WITH THIS UNCERTAINTY...HAVE KEPT
NEAR CLIMATOLOGICAL CHANCES OF PRECIPITATION OVER THE TFX CWA FRIDAY
THROUGH SATURDAY...WITH TEMPERATURES COOLING TO NEAR SEASONAL
NORMALS BY SATURDAY. AN UPPER LEVEL RIDGE THEN BEGINS TO MOVE INTO
THE WESTERN UNITED STATES SATURDAY NIGHT...WHICH SHOULD CAUSE THE
CHANCE FOR PRECIPITATION TO DECREASE. UPPER LEVEL SUPPORT FOR THE
INCREASING WINDS THROUGH THIS PERIOD IS TEMPORARY. THEREFORE...AM
NOT ANTICIPATING HIGH WIND HIGHLIGHTS AT THIS TIME AND WILL NOT
MENTION IN THE HAZARDOUS WEATHER OUTLOOK. HOWEVER...THE POTENTIAL
FOR BRIEF PERIODS OF STRONG WINDS STILL REMAINS...AND THE SITUATION
WILL CONTINUE TO BE MONITORED. COULSTON
&&
.AVIATION...
UPDATED 0600Z.
AN UPPER LEVEL TROF OF LOW PRESSURE WILL MOVE EASTWARD TOWARDS
CENTRAL/SOUTHWEST MONTANA LATE TONIGHT. EXPECT GENERALLY OVERCAST
CONDITIONS UNTIL 00Z SUNDAY...WITH THE CHANCE FOR SNOW DEVELOPING
AFTER 09Z OVER WESTERN AND SOUTHWESTERN MONTANA. THE BEST CHANCE FOR
SNOW ON SATURDAY WILL BE ON SATURDAY FROM 13Z TO 20Z IN THE BOZEMAN
AND WEST YELLOWSTONE AREA. THUS IFR/LIFR CONDITIONS WILL BE POSSIBLE
AT TIMES OVER THIS REGION. MOUNTAINS WILL BE OBSCURED AT TIMES
THROUGHOUT THE REGION THOUGH THE PERIOD. ADDITIONALLY...EXPECT
SURFACE WINDS TO BECOME VERY BREEZY OVER NORTH CENTRAL MONTANA AFTER
09Z SATURDAY. EXPECT A GENERALLY CLEARING TREND WITH LIGHTER WINDS
EXPECTED FROM 0Z SUNDAY UNTIL 6Z SUNDAY. BRUSDA
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 44 25 41 27 / 10 0 20 20
CTB 42 23 39 26 / 10 0 20 20
HLN 43 23 41 26 / 20 0 30 30
BZN 37 13 37 16 / 50 0 30 40
WEY 31 8 30 12 / 90 30 80 60
DLN 34 14 34 13 / 50 0 40 40
HVR 48 19 45 25 / 10 10 10 10
LWT 43 18 38 21 / 10 0 10 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 5 PM MST THIS AFTERNOON FOR MTZ009-010.
&&
$$
SHORT TERM...BLANK
LONG TERM...COULSTON
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 211042
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
342 AM MST SAT NOV 21 2009
.DISCUSSION...A VIGOROUS COLD FRONT HAS CROSSED MUCH OF THE NORTHERN
ROCKIES EARLY THIS MORNING AND WILL BE EAST OF THE CONTINENTAL
DIVIDE BY SUNRISE. THIS FEATURE HAS PRODUCED A COUPLE TO SEVERAL
INCHES OF SNOW MAINLY ACROSS NORTH CENTRAL IDAHO AS INDICATED BY
SNOTEL SENSORS AND HIGHWAY CAMERAS AT LOLO AND LOST TRAIL PASSES.
STRONG WINDS...PARTICULARLY IN THE MOUNTAINS HAVE ALSO RESULTED
FROM THE FRONTAL PASSAGES. THE AIR MASS BEHIND THE FRONT AND UNDER
A PASSING UPPER LEVEL TROUGH WILL BE VERY UNSTABLE AND MOIST
THROUGH MIDDAY. THEREFORE...ALL AREAS WILL SEE SNOW SHOWERS
DEVELOP. NORTH CENTRAL IDAHO WILL CONTINUE TO SEE THE BEST
ACCUMULATIONS...AND THUS THE WINTER WEATHER ADVISORY WILL BE
CONTINUED THROUGH LATE MORNING. BLOWING SNOW MAY CAUSE AREAS OF
POOR VISIBILITY IN THE MOUNTAINS AS WINDS ARE EXPECTED TO STAY
BREEZY.
A SECOND SYSTEM WILL BARREL INTO THE NORTHERN ROCKIES SUNDAY. THIS
WILL ALSO BE A GOOD SNOW PRODUCER SIMILAR TO THE CURRENT TROUGH.
AND AGAIN NORTH CENTRAL IDAHO WILL SEE THE GREATEST
ACCUMULATIONS AND HAVE ISSUED A SECOND WINTER WEATHER ADVISORY FOR
THAT AREA SUNDAY THROUGH SUNDAY EVENING. THE BITTERROOTS WILL ALSO
SEE SEVERAL INCHES OF SNOW WITH THIS EVENT FROM LOOKOUT PASS AREA
SOUTH TO LOST TRAIL PASS...SO HAVE INCLUDED THIS AREA IN THE
ADVISORY. THIS SYSTEM WILL ALSO HAVE INCREASED WINDS WITH SOME
BLOWING SNOW POSSIBLE.
LIGHT ACCUMULATION IN THE VALLEYS ARE POSSIBLE BOTH TODAY AND WITH
SUNDAY`S SYSTEM AS SNOW LEVELS HAVE LOWERED TO ALL BUT THE LOWEST
VALLEYS IN NORTH CENTRAL IDAHO.
MONDAY THROUGH THE WEEK...THE NORTHERN ROCKIES WILL ENTER INTO A
RIDGING PATTERN THROUGH THE BULK OF NEXT WEEK. THE FIRST HINTS OF A
RIDGE OF HIGH PRESSURE WILL FORM THROUGHOUT THE DAY MONDAY...BUT
MAY BE INTERRUPTED BY A SHORTWAVE PASSING TO THE NORTH IN CANADA.
WHILE THIS WAVE DOESNT LOOK TO MOVE FAR ENOUGH SOUTH TO HAVE ANY
TRUE AFFECTS ON THE REGION...FLOW WILL REMAIN UNSTABLE
ENOUGH IN NORTHWEST MONTANA FOR SHOWERY PRECIPITATION TO
OCCUR BUT REMAIN CONFINED MOSTLY TO HIGHER ELEVATIONS. HIGH
PRESSURE WILL THEN HAVE A BETTER CHANCE TO REBUILD OVER THE
NORTHERN ROCKIES TUESDAY NIGHT AND WILL CONTINUE TO STRENGTHEN
THROUGH THE END OF THE WEEK.
&&
.AVIATION...SNOW SHOWERS WILL DEVELOP UNDER AN UNSTABLE UPPER
TROUGH THROUGH THE MORNING CAUSING INTERMITTENT VISIBILITY AND
CEILING REDUCTIONS AT ALL TERMINALS. THE SHOWERS WILL DECREASE
SOMEWHAT IN COVERAGE BY LATE AFTERNOON BUT LIKELY CONTINUE OVER
THE MOUNTAINS INTO THE EARLY EVENING.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY FROM 5 AM TO 11 PM MST SUNDAY FOR
LOWER CLARK FORK REGION.
WINTER WEATHER ADVISORY FROM 5 AM TO 11 PM MST SUNDAY FOR
BITTERROOT/SAPPHIRE MOUNTAINS.
ID...WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR
NORTHERN CLEARWATER MOUNTAINS-SOUTHERN CLEARWATER MOUNTAINS.
WINTER WEATHER ADVISORY FROM 4 AM TO 10 PM PST SUNDAY FOR
NORTHERN CLEARWATER MOUNTAINS-SOUTHERN CLEARWATER MOUNTAINS.
&&
$$
SHORT TERM...WHITMORE
LONG TERM....ALLEGRETTO
AVIATION...WHITMORE
000
FXUS65 KGGW 210947
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
247 AM MST SAT NOV 21 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH MONDAY...
AN ENERGETIC SHORT WAVE TROUGH AND COLD FRONT SWEEP OVER THE ZONES
TODAY. THE MAIN EFFECT WILL BE STRONG WINDS WESTERLY WINDS BEHIND
THE FRONT. A STRONG SURFACE TROUGH ANCHORED BY A LOW CENTERED IN
SOUTHERN SASKATCHEWAN WILL MAINTAIN A STRONG PRESSURE GRADIENT
ACROSS THE SURFACE. THESE WINDS WILL BE REINFORCED BY 850MB WINDS
OF 35-40KTS RESULTING IN SURFACE WIND GUSTS OF EQUAL STRENGTH. THE
LWA SEEMS LIKE A SLAM-DUNK SO WILL RENEW THE NPW DURING THIS
PACKAGE. MOISTURE IS RATHER ANEMIC WITH THIS SYSTEM SO EXPECT
MOSTLY CLOUD COVER WITH LITTLE PRECIPITATION. A VORT MAX AROUND
THE BASE OF THE UPPER LEVEL TROUGH COULD PRODUCE SOME MOISTURE IN
SOUTHERN ALBERTA/SASKATCHEWAN THAT MIGHT SPREAD A BIT ACROSS THE
INTERNATIONAL BORDER. SO WILL MAINTAIN POPS JUST BELOW TEXT
MENTION FOR NOW. THE OTHER PREVIOUSLY MENTIONED CONCERN WAS THE
EXPECTED LOW RH VALUES FOR TODAY WHICH COULD PRODUCE NEAR CRITICAL
FIRE WEATHER CONDITIONS. SEE FIRE WX SEPARATE DISCUSSION BELOW.
TONIGHT/SUNDAY...UPPER FLOW VEERS TO THE NORTHWEST LATE TONIGHT AS
THE UPPER TROUGH BASE MOVES EAST. A SHORT WAVE UPPER RIDGE FOLLOWS
BUT IS QUICKLY FOLLOWED BY THE NEXT SHORT WAVE TROUGH. THIS NEXT
WAVE SENDS A WEAK COLD FRONT INTO THE CWA BY AFTERNOON WHICH COULD
PRODUCE LIGHT PRECIPITATION OVER THE WESTERN ZONES. 850MB
TEMPERATURES REMAIN NEAR 0*C OR JUST BELOW SO MIXED PRECIPITATION
IS A POSSIBILITY. WITH THE ATMOSPHERE DECOUPLING AT SUNSET...THE
RELAXING GRADIENT WILL ALLOW WINDS TO DROP BELOW LWA CRITERIA.
SUNDAY NIGHT/MONDAY...THE BASE OF THE TROUGH DROPS SOUTH INTO
NORTHERN COLORADO...TAKING MOST OF THE ENERGY TO OUR SOUTH.
HOWEVER THE INVERTED SURFACE EXTENDS NORTH INTO NORTHEASTERN
MONTANA WHICH WILL KEEP CONDITIONS A BIT UNSETTLED. WHILE
NAM...UKMET AND EC STAY DRY...BASED ON GFS...GEM AND SREF...SLIGHT
CHANCE POPS SEEM APPROPRIATE FOR SNOW OVERNIGHT. CONDITIONS DO
NOT CHANGE MUCH FOR MONDAY SO WILL KEEP SLIGHT CHANCE POPS GOING.
SURFACE HIGHS WILL DROP DOWN MUCH CLOSER TO NORMAL WHILE 850MB
TEMPERATURES HOVER AROUND -4*C. SO EXPECT ANY PRECIPITATION TO
FALL AS SNOW AND POSSIBLY RAIN SHOWERS. QPF AMOUNTS WILL NOT
PRODUCE ACCUMULATIONS. SCT
.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
SHORTWAVE TROUGH DROPS SOUTHEAST OUT OF SASKATCHEWAN DURING THE
DAY TUESDAY AND MAY BRING A SLIGHT CHANCE OF RAIN OR SNOW. THIS
FAST MOVING SYSTEM WILL HAVE LIMITED MOISTURE WITH IT.
AN UPPER RIDGE BUILDS INTO THE AREA ON WEDNESDAY AND WILL BRING
WARM AND DRY WEATHER THROUGH THANKSGIVING DAY FOR SURE.
MODELS HAVE SOME DIFFERENCES ON TRACK OF A SHORTWAVE THAT MOVES
INLAND FROM THE PACIFIC ON FRIDAY. ECMWF TAKES THE SYSTEM SOUTH OF
THE AREA WHILE THE GFS BRINGS IT ACROSS MONTANA. EITHER WAY...A
COLD FRONT WILL AFFECT THE FORECAST AREA ON FRIDAY WITH COOLER
TEMPERATURES EXPECTED NEXT WEEKEND. WILL KEEP THE FORECAST DRY FOR
THE MOST PART FOR NOW. FORRESTER
&&
.AVIATION...
VFR CONDITIONS. A MIX OF MID AND HIGH LEVEL CLOUDS WILL MOVE
THROUGH THE AREA TODAY WITH SKIES CLEARING TONIGHT. SOUTHEAST
WINDS EARLY THIS MORNING WILL BECOME WEST AROUND 15Z AND INCREASE
TO 20 TO 25 KNOTS BY 18Z. THE WINDS WILL DIMINISH TO 10 TO 15
KNOTS THIS EVENING.
&&
.FIRE WEATHER...
A STRONG WEST WIND WILL DEVELOP TODAY BEHIND A COLD FRONT. WIND
SPEEDS ARE EXPECTED TO REACH 20 TO 30 MPH...WITH GUSTS TO 40 MPH
DURING THE LATE MORNING AND AFTERNOON HOURS. AFTERNOON MINIMUM
RELATIVE HUMIDITY VALUES ARE EXPECTED TO BRIEFLY DROP INTO THE 20
TO 30 PERCENT RANGE BEFORE BEGINNING A STEADY RECOVERY NEAR
SUNSET. THEREFORE...A BRIEF PERIOD OF CRITICAL FIRE WEATHER
CONDITIONS ARE POSSIBLE THIS AFTERNOON...BUT HIGHLIGHTS ARE NOT
EXPECTED AT THIS TIME DUE TO THE SHORT DURATION OF LOW RELATIVE
HUMIDITY DUE TO SHORTENING SUNLIGHT HOURS. THE MOST SUSCEPTIBLE
AREAS WILL BE THE LITTLE ROCKY MOUNTAINS AND THE MISSOURI BREAKS
REGION OF ZONES 119 AND 121...WHICH WILL EXPERIENCE A RATHER POOR
RELATIVE HUMIDITY RECOVERY LAST NIGHT. AJZ/SCT
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM 10 AM THIS MORNING TO 5 PM MST THIS
AFTERNOON FOR FORT PECK LAKE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 210946
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
246 AM MST SAT NOV 21 2009
.SHORT TERM...VALID FOR TDY AND SUN...
PROGRESSIVE WEATHER PATTERN TO BE OVER THE FORECAST AREA THIS
WEEKEND AND INTO THE DAY MONDAY. LARGE TROUGH CURRENTLY MOVING
ONTO AND ACROSS THE PACIFIC NORTHWEST AND INTO THE NORTHERN
ROCKIES REGION. SATELLITE SHOWING A DEEP SOUTHWEST FLOW ALOFT
ACROSS THE STATE WITH PLENTY OF MID AND HIGH LEVEL CLOUDS MOVING
ACROSS OUR AREA. RADARS ACROSS IDAHO SHOWING CONVECTIVE TYPE
PRECIP NOW MOVING UP INTO THE SOUTHWEST PORTIONS OF THE STATE AND
APPROACHING OUR SOUTHWEST MOUNTAINS. A FEW LIGHTING STRIKES HAVE
ALSO BEEN OBSERVED ACROSS CENTRAL IDAHO INDICATING FAIRLY STRONG
DYNAMICS AND INSTABILITY FOR THIS TIME OF YEAR. WILL CONTINUE
WITH LIKELY POPS FOR THE SOUTHWEST MOUNTAINS WITH CHANCE POPS FOR
THE CENTRAL AND WESTERN ZONES THIS MORNING WITH BEST CHANCES
WEST. SNOWFALL COULD BE HEAVY FOR A SHORT WHILE OVER THE
BEARTOOTH/ABSAROKA MOUNTAINS RESULTING IN SEVERAL INCHES OF SNOW
THIS MORNING.
A COLD FRONT IS EXPECTED TO MOVE ACROSS THE CENTRAL AND WESTERN
PORTIONS OF THE FORECAST AREA BETWEEN 12-15Z AND THE EASTERN ZONES
BY EARLY AFTERNOON. DYNAMICS AND MOISTURE DECREASE BEHIND THE
FRONT RESULTING IN ONLY CHANCE POPS OVER THE MOUNTAINS...WITH
SLIGHT CHANCES SPREADING EAST DURING THE AFTERNOON. EXPECT WINDY
CONDITIONS TO DEVELOP BEHIND THE FRONT ACROSS THE PLAINS. THIS
DOWNSLOPE FLOW WILL HELP TO INHIBIT PRECIP ACROSS THE PLAINS.
DYNAMICS ALSO LOOK TO WEAKEN AS THE TROUGH MOVES ACROSS THE
FORECAST AREA SO FOR NOW WILL CONTINUE WITH ONLY A SLIGHT CHANCE
FOR SHOWERS ACROSS THE PLAINS TODAY.
RIDGING QUICKLY MOVES ACROSS THE CENTRAL PORTIONS OF THE STATE
TONIGHT BRINGING AN END TO ANY SHOWER ACTIVITY. HOWEVER...LEE-
SIDE TROUGHING DEVELOPS ACROSS THE FORECAST AREA LATE TONIGHT IN
ADVANCE OF THE NEXT FAST MOVING TROUGH ACROSS THE PACIFIC
NORTHWEST. PRESSURE GRADIENTS TIGHTEN ONCE AGAIN ACROSS THE
UPPER YELLOWSTONE AND STILLWATER VALLEYS LATE TONIGHT THROUGH
SUNDAY MORNING. AS A RESULT...HAVE PUT SUB-ADVISORY WINDS ACROSS
THESE AREAS FOR THIS TIME. ANOTHER COLD FRONT MOVES THROUGH LATE
SUNDAY MORNING WHICH WILL SHUT THE STRONGER WINDS OFF IN THE
LIVINGSTON AREA. THE GFS CONTINUES TO SHIFT THE BULK OF PRECIP
SOUTH ACROSS WESTERN WYOMING SO WILL CONTINUE WITH JUST A SLIGHT
CHANCE TO CHANCE POPS FOR OUR PLAINS WITH LIKELY POPS RETURNING
FOR THE MOUNTAINS. TEMPERATURES TODAY WILL BE COOLER BUT STILL
REMAIN ABOVE NORMAL BEFORE MORE NORMAL TEMPERATURES ARRIVE FOR
SUNDAY WITH READINGS IN THE UPPER 30S TO LOWER 40S. HOOLEY
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
A PROGRESSIVE PATTERN DEVELOPS OVER THE FORECAST AREA FOR THE
EXTENDED. 3 SYSTEMS WILL IMPACT THE AREA NEXT WEEK...BUT
RIDGING ON THANKSGIVING BRINGS WARM...DRY AND BREEZY CONDITIONS TO
THE AREA. THE FIRST SYSTEM IS OVER THE AREA MONDAY...SHIFTING
SOUTHEAST MONDAY NIGHT. INCREASED POPS OVER EASTERN AREAS MONDAY
AS WELL AS KEEPING SOME POPS FOR WESTERN MOUNTAIN AND FOOTHILLS
LOCATIONS. TEMPERATURES DON`T LOOK TERRIBLY COLD WITH THIS SYSTEM
IN THE LOWER 40S...AND COULD BE A TAD COOLER IN SOME LOCATIONS
WHERE CLOUDS AND PRECIPITATION OCCUR. AN ALBERTA CLIPPER SYSTEM
QUICKLY MOVES THROUGH EASTERN AREAS ON TUESDAY AFTERNOON...THOUGH
NOT BEFORE TEMPERATURES CLIMB INTO THE LOW TO MID 40S. IF TIMING
OF THE CLIPPER IS FASTER WILL NEED TO COOL EASTERN AREAS 5 TO 10
DEGREES. RIDGING BUILDS INTO THE AREA WEDNESDAY AND THURSDAY WITH
DOWNSLOPE WIND GRADIENT IN PLACE PUSHING TEMPERATURES BACK INTO
THE 50S. THE FINAL SYSTEM ARRIVES FRIDAY OR SATURDAY DEPENDING ON
MODEL PREFERENCE. THE ECMWF DIGS THE LATE WEEK SYSTEM FURTHER TO
THE SOUTH AND BRINGS COOLER AIR INTO THE AREA FRIDAY
AFTERNOON...WHILE THE GFS IS LESS DEEP WITH THE SYSTEM KEEPING THE
ENERGY OVER MONTANA AND WYOMING AND BRINGS COLDER AIR IN FOR
SATURDAY. 00Z ENSEMBLE DATA SUPPORTIVE OF THE OPERATIONAL GFS
KEEPING TROF FURTHER NORTH...AND TRENDED FORECAST TOWARD THE GFS
FOR THE LATER PERIODS...INCLUDING INCREASING POPS AND LOWERING
TEMPERATURES JUST A TAD. CHAMBERS
&&
.AVIATION...
A COLD FRONT WILL MOVE THROUGH THE AREA THIS MORNING. MVFR WITH
OCCASIONAL IFR CONDITIONS WILL DEVELOP EARLY THIS MORNING OVER
WESTERN AREAS...INCLUDING KLVM...LASTING INTO EARLY AFTERNOON. AS
THE FRONT MOVES EASTWARD CONDITIONS SHOULD REMAIN PRIMARILY VFR
WITH LOCAL MVFR CONDITIONS ASSOCIATED WITH ISOLATED SHOWER
ACTIVITY. MOUNTAIN OBSCURATION WILL LAST INTO LATE AFTERNOON FOR
WESTERN MOUNTAINS...AND INTO THIS EVENING FOR THE BIG HORN
MOUNTAINS...AS CONDITIONS IMPROVE FROM WEST TO EAST. GUSTY
NORTHWEST WINDS ARE EXPECTED ACROSS THE AREA BEHIND THE FRONT THIS
AFTERNOON. CHAMBERS
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SUN MON TUE WED THU FRI
-------------------------------------------------------
BIL 048 023/040 028/042 024/046 030/051 036/055 035/051
2/W 02/W 21/B 11/B 00/B 00/U 02/W
LVM 041 020/036 020/035 018/043 025/050 029/054 031/046
4/J 04/J 32/J 12/W 10/B 00/B 03/W
HDN 051 024/043 024/044 019/047 025/052 031/057 030/053
2/W 02/W 22/W 12/W 00/B 00/U 02/W
MLS 053 022/045 024/043 020/047 023/046 030/056 031/051
1/N 02/W 22/W 22/W 10/B 00/U 01/U
4BQ 051 023/042 021/042 019/045 022/046 028/056 029/051
1/N 22/W 22/J 12/W 00/B 00/U 01/U
BHK 053 021/045 021/040 019/043 020/040 024/054 027/051
1/N 11/B 22/J 22/W 10/B 00/U 01/U
SHR 047 020/043 022/039 014/046 024/050 028/056 028/051
3/W 22/W 22/J 11/B 00/B 00/U 01/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 210544
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1100 PM MST FRI NOV 20 2009
UPDATED AVIATION SECTION
.UPDATE...
PROGRESSION OF SHORTWAVE TROUGH SEEMS TO HAVE SLOWED A BIT MORE SO
HAVE LOWERED OVERNIGHT POPS ALONG THE CONTINENTAL DIVIDE AND
PORTIONS OF CENTRAL MONTANA. WEAK COLD FRONT STILL EXPECTED TO
PUSH THROUGH THE AREA OVERNIGHT...WITH TEMPERATURES FALLING CLOSER
TO SEASONAL AVERAGES ON SATURDAY. LIGHT SNOW WILL DEVELOP ALONG
THE CONTINENTAL DIVIDE AFTER MIDNIGHT WITH LIGHT SNOW ACCUMULATION
OF 1 TO 2 INCHES POSSIBLE. GUSTY WINDS AND FALLING SNOW MAY CAUSE
TIMES OF REDUCED VISIBILITIES ALONG THE MOUNTAIN PASSES. MLS
&&
.AVIATION...
UPDATED 0600Z.
AN UPPER LEVEL TROF OF LOW PRESSURE WILL MOVE EASTWARD TOWARDS
CENTRAL/SOUTHWEST MONTANA LATE TONIGHT. EXPECT GENERALLY OVERCAST
CONDITIONS UNTIL 00Z SUNDAY...WITH THE CHANCE FOR SNOW DEVELOPING
AFTER 09Z OVER WESTERN AND SOUTHWESTERN MONTANA. THE BEST CHANCE FOR
SNOW ON SATURDAY WILL BE ON SATURDAY FROM 13Z TO 20Z IN THE BOZEMAN
AND WEST YELLOWSTONE AREA. THUS IFR/LIFR CONDITIONS WILL BE POSSIBLE
AT TIMES OVER THIS REGION. MOUNTAINS WILL BE OBSCURED AT TIMES
THROUGHOUT THE REGION THOUGH THE PERIOD. ADDITIONALLY...EXPECT
SURFACE WINDS TO BECOME VERY BREEZY OVER NORTH CENTRAL MONTANA AFTER
09Z SATURDAY. EXPECT A GENERALLY CLEARING TREND WITH LIGHTER WINDS
EXPECTED FROM 0Z SUNDAY UNTIL 6Z SUNDAY. BRUSDA
&&
.PREV DISCUSSION...
/ISSUED 500 PM MST FRI NOV 20 2009/
AN UPPER LEVEL TROUGH OF LOW PRESSURE...CURRENTLY MOVING ONTO THE
WEST COAST...WILL TRACK EAST ACROSS THE REGION LATE TONIGHT
THROUGH EARLY SATURDAY AFTERNOON. A BRIEF PERIOD OF RIDGING BEHIND
THIS INITIAL SYSTEM SATURDAY NIGHT WILL BE QUICKLY FOLLOWED BY
ANOTHER TROUGH MOVING INTO THE NORTHERN ROCKIES ON SUNDAY. A COLD
FRONT ASSOCIATED WITH THE INITIAL TROUGH WILL MOVE EAST ACROSS THE
REGION LATE TONIGHT. MOISTURE WILL INCREASE ALONG AND BEHIND THE
FRONT WITH SNOW SHOWERS DEVELOPING AFTER MIDNIGHT OVER THE ROCKY
MTN FRONT AND GLACIER PARK AREA...SPREADING EAST OVER SW MT LATE
TONIGHT THROUGH SATURDAY MORNING. WESTERLY DOWNSLOPE FLOW WILL
LIMIT PRECIPITATION CHANCES OVER THE PLAINS...HOWEVER OCCASIONAL
SNOW SHOWERS OVER THE MTNS MAY BRING ACCUMULATIONS OF 1 TO 3
INCHES TO ELEVATIONS ABOVE 6000 FT. SIGNIFICANT COOLING WILL OCCUR
BEHIND THE FRONT OVER THE FORECAST AREA ON SATURDAY...HOWEVER THIS
WILL ONLY MEAN TEMPERATURES DROPPING BACK TO SEASONAL AVERAGES.
MODELS HAVE BEEN TRENDING SLOWER AND DEEPER WITH THE SECOND SYSTEM
TO ARRIVE ON SUNDAY AND THIS SYSTEM WILL LIKELY BRING ANOTHER
ROUND OF SNOW SHOWERS TO THE MTNS WITH PERHAPS A LITTLE BETTER
CHANCE OF SNOW SHOWERS EXTENDING FARTHER EAST ONTO THE PLAINS DUE
TO DEEPER MOISTURE AND MARGINAL INSTABILITY. ACCUMULATING SNOW
AGAIN LOOKS TO BE CONFINED MAINLY TO THE MOUNTAINOUS AREAS WITH
ANOTHER 1 TO 3 INCHES POSSIBLE ABOVE 6000 FEET. GUSTY SOUTHWEST
WINDS WILL SHIFT TO THE WEST BEHIND TONIGHTS COLD COLD FRONT WITH
WESTERN PORTIONS OF NORTH CENTRAL MT AND MTN PASSES SEEING THE
STRONGEST WINDS WITH GUSTY WINDS CONTINUING THROUGH THE WEEKEND.
COMBINATION OF GUSTY WINDS AND PERIODS OF LIGHT SNOW MAY HAVE AN
IMPACT TO TRAVELERS OVER MTN PASSES THIS WEEKEND AND WILL
HIGHLIGHT THIS IN THE HAZARDOUS WEATHER OUTLOOK. HOENISCH
SUNDAY NIGHT THROUGH FRIDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT WITH MOVING THE UPPER LEVEL TROUGH OUT OF THE AREA
SUNDAY NIGHT INTO MONDAY FOR A DECREASING CHANCE OF PRECIPITATION.
AS THE COLD FRONT ASSOCIATED WITH THIS SYSTEM ALSO MOVES THROUGH THE
AREA SUNDAY NIGHT...WEST WINDS WILL BECOME BREEZY AND GUSTY. THESE
WINDS WILL DECREASE ON MONDAY AS THE FRONT EXITS THE AREA TO THE
EAST...AS TEMPERATURES CONTINUE TO HOVER AROUND NORMAL. THE UPPER
LEVEL HIGH PRESSURE RIDGE OVER THE EASTERN PACIFIC WILL THEN BEGIN
TO BUILD BACK INTO THE WESTERN UNITED STATES MONDAY NIGHT THROUGH
TUESDAY NIGHT. HOWEVER...A WEAK SHORTWAVE WILL MOVE DOWN THE EAST
SIDE OF THE RIDGE AND THROUGH MONTANA DURING THIS TIME. THIS WILL
BRING A CHANCE OF PRECIPITATION TO THE AREA ONCE AGAIN...BUT IT WILL
MAINLY BE IN THE MOUNTAINS AS WESTERLY DOWNSLOPE WINDS WILL INCREASE
WITH THE PASSAGE OF THE SHORTWAVE. THESE WINDS WILL ALSO WARM
TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE NORMAL ON TUESDAY. THE
UPPER LEVEL RIDGE WILL THEN BUILD INTO MONTANA TUESDAY NIGHT THROUGH
THURSDAY (THANKSGIVING DAY)...WHICH WILL KEEP ONLY A SLIGHT CHANCE
OF PRECIPITATION IN THE WESTERN MONTANA MOUNTAINS. ALSO...WESTERLY
DOWNSLOPE WINDS WILL INCREASE ONCE AGAIN THROUGH THIS PERIOD...WHICH
WILL KEEP TEMPERATURES ABOUT 10 DEGREES ABOVE NORMAL. THE MODELS
BEGIN TO DIVERGE FOR THE REMAINDER OF THIS FORECAST PERIOD. THE GFS
IS MUCH FASTER THAN THE ECMWF WITH BRINGING THE NEXT PACIFIC WEATHER
SYSTEM THROUGH THE AREA. THE GFS MOVES IT THROUGH MONTANA ON
FRIDAY...WHILE THE ECMWF IS 12 TO 24 HOURS SLOWER IN MOVING IT
THROUGH FRIDAY NIGHT INTO SATURDAY. WITH THIS UNCERTAINTY...HAVE
GONE WITH A WIDESPREAD CHANCE OF PRECIPITATION FOR FRIDAY AND FRIDAY
NIGHT...WITH THE CHANCE BEING HIGHER THAN CLIMATOLOGICAL AVERAGES.
HAVE ALSO COOLED TEMPERATURES CLOSER TO NORMAL. THE INCREASES IN WIND
SUNDAY NIGHT...MONDAY NIGHT AND TUESDAY...AND THANKSGIVING DAY
INTO FRIDAY WILL NEED TO BE MONITORED FOR POSSIBLE HIGHLIGHTS.
COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 36 42 25 41 / 0 10 0 30
CTB 31 40 24 39 / 10 10 0 20
HLN 29 41 23 41 / 20 20 0 40
BZN 23 37 13 37 / 20 50 0 40
WEY 22 29 8 30 / 50 90 30 90
DLN 27 32 14 34 / 40 50 0 50
HVR 29 49 21 45 / 0 10 10 20
LWT 32 42 20 38 / 0 10 0 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 210446
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
946 PM MST FRI NOV 20 2009
.UPDATE...
PROGRESSION OF SHORTWAVE TROUGH SEEMS TO HAVE SLOWED A BIT MORE SO
HAVE LOWERED OVERNIGHT POPS ALONG THE CONTINENTAL DIVIDE AND
PORTIONS OF CENTRAL MONTANA. WEAK COLD FRONT STILL EXPECTED TO
PUSH THROUGH THE AREA OVERNIGHT...WITH TEMPERATURES FALLING CLOSER
TO SEASONAL AVERAGES ON SATURDAY. LIGHT SNOW WILL DEVELOP ALONG
THE CONTINENTAL DIVIDE AFTER MIDNIGHT WITH LIGHT SNOW ACCUMULATION
OF 1 TO 2 INCHES POSSIBLE. GUSTY WINDS AND FALLING SNOW MAY CAUSE
TIMES OF REDUCED VISIBILITIES ALONG THE MOUNTAIN PASSES. MLS
&&
.AVIATION...
UPDATED 0000Z.
AN UPPER LEVEL TROF OF LOW PRESSURE WILL MOVE EASTWARD TOWARDS
CENTRAL/SOUTHWEST MONTANA LATE TONIGHT. EXPECT GENERALLY OVERCAST
CONDITIONS THROUGH THE PERIOD...WITH THE CHANCE FOR SNOW DEVELOPING
AFTER 09Z OVER WESTERN AND SOUTHWESTERN MONTANA. THE BEST CHANCE FOR
SNOW ON SATURDAY WILL BE ON SATURDAY FROM 14Z TO 20Z IN THE BOZEMAN
AND WEST YELLOWSTONE AREA. THUS IFR/LIFR CONDITIONS WILL BE POSSIBLE
AT TIMES OVER THIS REGION. MOUNTAINS WILL BE OBSCURED AT TIMES
THROUGHOUT THE REGION THOUGH THE PERIOD. ADDITIONALLY...EXPECT
SURFACE WINDS TO BECOME VERY BREEZY OVER NORTH CENTRAL MONTANA AFTER
09Z SATURDAY. BRUSDA
&&
.PREV DISCUSSION...
/ISSUED 500 PM MST FRI NOV 20 2009/
AN UPPER LEVEL TROUGH OF LOW PRESSURE...CURRENTLY MOVING ONTO THE
WEST COAST...WILL TRACK EAST ACROSS THE REGION LATE TONIGHT
THROUGH EARLY SATURDAY AFTERNOON. A BRIEF PERIOD OF RIDGING BEHIND
THIS INITIAL SYSTEM SATURDAY NIGHT WILL BE QUICKLY FOLLOWED BY
ANOTHER TROUGH MOVING INTO THE NORTHERN ROCKIES ON SUNDAY. A COLD
FRONT ASSOCIATED WITH THE INITIAL TROUGH WILL MOVE EAST ACROSS THE
REGION LATE TONIGHT. MOISTURE WILL INCREASE ALONG AND BEHIND THE
FRONT WITH SNOW SHOWERS DEVELOPING AFTER MIDNIGHT OVER THE ROCKY
MTN FRONT AND GLACIER PARK AREA...SPREADING EAST OVER SW MT LATE
TONIGHT THROUGH SATURDAY MORNING. WESTERLY DOWNSLOPE FLOW WILL
LIMIT PRECIPITATION CHANCES OVER THE PLAINS...HOWEVER OCCASIONAL
SNOW SHOWERS OVER THE MTNS MAY BRING ACCUMULATIONS OF 1 TO 3
INCHES TO ELEVATIONS ABOVE 6000 FT. SIGNIFICANT COOLING WILL OCCUR
BEHIND THE FRONT OVER THE FORECAST AREA ON SATURDAY...HOWEVER THIS
WILL ONLY MEAN TEMPERATURES DROPPING BACK TO SEASONAL AVERAGES.
MODELS HAVE BEEN TRENDING SLOWER AND DEEPER WITH THE SECOND SYSTEM
TO ARRIVE ON SUNDAY AND THIS SYSTEM WILL LIKELY BRING ANOTHER
ROUND OF SNOW SHOWERS TO THE MTNS WITH PERHAPS A LITTLE BETTER
CHANCE OF SNOW SHOWERS EXTENDING FARTHER EAST ONTO THE PLAINS DUE
TO DEEPER MOISTURE AND MARGINAL INSTABILITY. ACCUMULATING SNOW
AGAIN LOOKS TO BE CONFINED MAINLY TO THE MOUNTAINOUS AREAS WITH
ANOTHER 1 TO 3 INCHES POSSIBLE ABOVE 6000 FEET. GUSTY SOUTHWEST
WINDS WILL SHIFT TO THE WEST BEHIND TONIGHTS COLD COLD FRONT WITH
WESTERN PORTIONS OF NORTH CENTRAL MT AND MTN PASSES SEEING THE
STRONGEST WINDS WITH GUSTY WINDS CONTINUING THROUGH THE WEEKEND.
COMBINATION OF GUSTY WINDS AND PERIODS OF LIGHT SNOW MAY HAVE AN
IMPACT TO TRAVELERS OVER MTN PASSES THIS WEEKEND AND WILL
HIGHLIGHT THIS IN THE HAZARDOUS WEATHER OUTLOOK. HOENISCH
SUNDAY NIGHT THROUGH FRIDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT WITH MOVING THE UPPER LEVEL TROUGH OUT OF THE AREA
SUNDAY NIGHT INTO MONDAY FOR A DECREASING CHANCE OF PRECIPITATION.
AS THE COLD FRONT ASSOCIATED WITH THIS SYSTEM ALSO MOVES THROUGH THE
AREA SUNDAY NIGHT...WEST WINDS WILL BECOME BREEZY AND GUSTY. THESE
WINDS WILL DECREASE ON MONDAY AS THE FRONT EXITS THE AREA TO THE
EAST...AS TEMPERATURES CONTINUE TO HOVER AROUND NORMAL. THE UPPER
LEVEL HIGH PRESSURE RIDGE OVER THE EASTERN PACIFIC WILL THEN BEGIN
TO BUILD BACK INTO THE WESTERN UNITED STATES MONDAY NIGHT THROUGH
TUESDAY NIGHT. HOWEVER...A WEAK SHORTWAVE WILL MOVE DOWN THE EAST
SIDE OF THE RIDGE AND THROUGH MONTANA DURING THIS TIME. THIS WILL
BRING A CHANCE OF PRECIPITATION TO THE AREA ONCE AGAIN...BUT IT WILL
MAINLY BE IN THE MOUNTAINS AS WESTERLY DOWNSLOPE WINDS WILL INCREASE
WITH THE PASSAGE OF THE SHORTWAVE. THESE WINDS WILL ALSO WARM
TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE NORMAL ON TUESDAY. THE
UPPER LEVEL RIDGE WILL THEN BUILD INTO MONTANA TUESDAY NIGHT THROUGH
THURSDAY (THANKSGIVING DAY)...WHICH WILL KEEP ONLY A SLIGHT CHANCE
OF PRECIPITATION IN THE WESTERN MONTANA MOUNTAINS. ALSO...WESTERLY
DOWNSLOPE WINDS WILL INCREASE ONCE AGAIN THROUGH THIS PERIOD...WHICH
WILL KEEP TEMPERATURES ABOUT 10 DEGREES ABOVE NORMAL. THE MODELS
BEGIN TO DIVERGE FOR THE REMAINDER OF THIS FORECAST PERIOD. THE GFS
IS MUCH FASTER THAN THE ECMWF WITH BRINGING THE NEXT PACIFIC WEATHER
SYSTEM THROUGH THE AREA. THE GFS MOVES IT THROUGH MONTANA ON
FRIDAY...WHILE THE ECMWF IS 12 TO 24 HOURS SLOWER IN MOVING IT
THROUGH FRIDAY NIGHT INTO SATURDAY. WITH THIS UNCERTAINTY...HAVE
GONE WITH A WIDESPREAD CHANCE OF PRECIPITATION FOR FRIDAY AND FRIDAY
NIGHT...WITH THE CHANCE BEING HIGHER THAN CLIMATOLOGICAL AVERAGES.
HAVE ALSO COOLED TEMPERATURES CLOSER TO NORMAL. THE INCREASES IN WIND
SUNDAY NIGHT...MONDAY NIGHT AND TUESDAY...AND THANKSGIVING DAY
INTO FRIDAY WILL NEED TO BE MONITORED FOR POSSIBLE HIGHLIGHTS.
COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 36 42 25 41 / 0 10 0 30
CTB 31 40 24 39 / 10 10 0 20
HLN 29 41 23 41 / 20 20 0 40
BZN 23 37 13 37 / 20 50 0 40
WEY 22 29 8 30 / 50 90 30 90
DLN 27 32 14 34 / 40 50 0 50
HVR 29 49 21 45 / 0 10 10 20
LWT 32 42 20 38 / 0 10 0 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KGGW 210418 AAA
AFDGGW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
918 PM MST FRI NOV 20 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
THE UPPER LEVEL TROUGH...CURRENTLY SLAMMING INTO THE NORTHWEST
COAST...CONTINUES TO EJECT MOISTURE INTO THE SOUTHWEST FLOW OVER
THE DIVIDE WHICH IS PRODUCING OPAQUE HIGH CLOUDS ABOVE
NORTHEASTERN MONTANA THIS EVENING. ADJUSTED SKY COVER FARTHER TO
THE EAST.
A LEE SURFACE TROUGH WILL SLIDE EAST OVER THE ZONES TONIGHT WHICH
WILL BACK SOUTHERLY WINDS TO THE WEST BY MORNING. A SURFACE
GRADIENT OF INCREASING STRENGTH WILL MAINTAIN WINDS TONIGHT AT
10KT-15KT OVER FAVORED AREAS. MADE A FEW TWEAKS TO THE WIND GRIDS
BASED ON CURRENT OBSERVATIONS AND UPDATED GUIDANCE.
OTHERWISE CONDITIONS WILL STAY DRY SO FEW GRID CORRECTIONS ARE
NEEDED. SCT
PREVIOUS DISCUSSION...
AN UPPER TROUGH IS MOVING OVER THE WEST COAST THIS AFTERNOON WITH
AN UPPER RIDGE REMAINING OVER THE NORTHERN HIGH PLAINS. A COPIOUS
AMOUNT OF UPPER LEVEL PACIFIC MOISTURE IS SPILLING OVER THE
CONTINENTAL DIVIDE RESULTING IN AN EXTENSIVE AREA OF DENSE CIRRUS
CLOUDS. THE OPAQUENESS OF THIS CIRRUS HAS GENERALLY HELD
TEMPERATURES BELOW FORECAST VALUES...BUT NEVERTHELESS STILL VERY
MILD FOR THE LATER HALF OF NOVEMBER.
THE TROUGH WILL CONTINUE ITS PROGRESSION EAST TONIGHT WITH HIGH
CLOUDS CONTINUING TO STREAM OVERHEAD. LOW TEMPERATURES WILL BE ON
THE MILD SIDE...WITH A FEW OF THE LOW LYING AREAS EXPERIENCING
COLD AIR DRAINAGE AS THE WIND BECOMES LIGHT. A PACIFIC COLD FRONT
ASSOCIATED WITH THE TROUGH WILL MOVE THROUGH SATURDAY MORNING WITH
A STRONG WEST WIND DEVELOPING DURING THE LATE MORNING AND
CONTINUING THROUGH THE AFTERNOON. COLD AIR ADVECTION AND
SUBSIDENCE SHOULD SUSTAIN THE SURFACE WIND ALONG WITH STRONGER
GUSTS AS 850MB WIND SPEEDS REACH NEAR 35KT. AFTERNOON RELATIVE
HUMIDITY VALUES COULD BE RATHER LOW WITH A DOWNSLOPING WESTERLY
WIND. A SHORT PERIOD OF NEAR CRITICAL FIRE WEATHER CONDITIONS ARE
POSSIBLE. SEE THE FIRE WEATHER DISCUSSION BELOW FOR MORE
INFORMATION. THE WIND SPEED WILL EASILY MEET LAKE WIND ADVISORY
CRITERIA...SO ONE WILL BE ISSUED FOR FORT PECK LAKE.
A SHORTWAVE RIDGE CROSSES THE NORTHERN PRAIRIE SATURDAY NIGHT AND
EARLY SUNDAY BRINGING AN END TO THE WIND AND LESS CLOUD COVER. LOW
TEMPERATURES SATURDAY NIGHT COULD APPROACH SEASONAL AVERAGES UNDER
A MOSTLY CLEAR SKY. A SHORTWAVE TROUGH QUICKLY ARRIVES SUNDAY
AFTERNOON. A FEW AREAS OF LIGHT RAIN ARE POSSIBLE IN THE
AFTERNOON. SURFACE TEMPERATURES APPEAR TOO WARM FOR ANY SNOW
DURING THE AFTERNOON. AJZ
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
NO SIGNIFICANT CHANGES IN THE LONG TERM PERIOD. SEVERAL WEAK
SHORTWAVE TROFS MOVE THROUGH THE REGION...ONE SUNDAY NIGHT WITH
ANOTHER ON TUESDAY. SOME POTENTIAL FOR PRECIPITATION WITH EITHER
OF THE WAVES SO KEPT THE LOW POPS FOR THOSE PERIODS. OTHERWISE
WITH THE MORE PROGRESSIVE FLOW TEMPERATURES WILL BE CLOSER TO
NORMAL BUT STILL WARM FOR LATE NOVEMBER.
PREVIOUS LONG TERM DISCUSSION....AN UPPER SHORT-WAVE TROUGH
SWINGS THROUGH EASTERN MONTANA SUNDAY NIGHT BUT APPEARS TO KEEP
MOST ENERGY TO OUR SOUTH. THE COLD FRONT IS RATHER SUBTLE SO DO
NOT EXPECT MUCH IN THE WAY OF QPF...BUT CANNOT RULE IT OUT EITHER.
WITH 850MB TEMPERATURES AT -2*C TO -4*C ANY PRECIPITATION THAT
DOES DEVELOP WILL LIKELY BE SNOW. THE GFS AND EC DO NOT BEGIN IN
PHASE...WITH THE GFS AROUND 6-HOURS AHEAD OF THE EC. SO WILL KEEP
12-HOURS POP/WX GRIDS. THE GEM ALSO FAVORS KEEPING MOST QPF TO OUR
SOUTH BUT SUPPORTS LOW POPS FOR OUR AREA. THE PHASE DIFFERENCE
BETWEEN GFS AND EC BECOMES MORE PRONOUNCED DURING THE REMAINDER OF
THE EXTENDED PERIOD AS THE MODELS BECOME MORE PROGRESSIVE.
MONDAY/MONDAY NIGHT...THE TROUGH MOVES TO THE EAST AS AN UPPER
RIDGE/WARM FRONT MOVES OVER THE WEST. THE RIDGE WILL LIKELY BE
SHORT LIVED SINCE MODELS SHOW ANOTHER SHORT WAVE TROUGH
APPROACHING. THE GEM IS SLOWER TO EXIT ANY PRECIPITATION SO WILL
MODIFY POPS BASED ON THE UNCERTAINTY.
TUESDAY/TUESDAY NIGHT...THE 00Z GFS AND 12Z EC AGREE WITH THE
SHORT-WAVE AFFECTING THE AREA BUT DIFFER QUITE A BIT ON LOCATION
AND TIMING. THE GFS BRINGS IN THE MOISTURE DURING THE DAY WHILE
THE EC PREFERS TUESDAY NIGHT. THE 00Z EC WHICH CAME IN DURING THE
SHIFT KEPT THE MOISTURE SOUTH OF THE AREA. THE GEM BY NOW APPEARS
TO BE ON A DIFFERENT PLANET...SO WILL DISREGARD. AGAIN ANY
PRECIPITATION THAT DEVELOPS WILL LIKELY BE LIGHT AND IN THE FORM
OF SNOW OR A MIX WITH MOST 850MB TEMPERATURES NEAR OR BELOW 0*C.
SURFACE TEMPERATURES WILL LIKELY DROP MUCH CLOSER TO NORMAL.
WEDNESDAY AND BEYOND...UPPER RIDGING APPEARS TO FOLLOW...ALTHOUGH
ENSEMBLE AND OPERATIONAL PHASING AND AMPLITUDE VARY GREATLY
BETWEEN GFS AND EC. SURFACE TEMPERATURES ARE EXPECTED TO ONCE
AGAIN RISE ABOVE NORMAL...BY AROUND 10*F TO 15*F. THE NEXT SHORT
WAVE TROUGH CRASHES INTO THE NORTHWEST COAST AROUND THURSDAY...BUT
THERE CONTINUES TO BE NO CONSENSUS AS TO HOW THE TROUGH DEVELOPS
AND AFFECTS NORTHEAST MONTANA. SCT
&&
.AVIATION...
VFR CONDITIONS. SCATTERED TO BROKEN HIGH CLOUDS WILL GIVE WAY TO
INCREASING MID-LEVEL CLOUDS LATE TONIGHT AS A COLD FRONT
APPROACHES THE AREA. EAST TO SOUTHEAST WINDS OVERNIGHT WILL TURN
NORTHWEST AND INCREASE BEHIND THE FRONTAL PASSAGE DURING THE LATE
MORNING. RAE
&&
.FIRE WEATHER...
A STRONG WEST WIND WILL DEVELOP SATURDAY BEHIND A COLD FRONT.
WIND SPEEDS ARE EXPECTED TO REACH 20 TO 30 MPH...WITH GUSTS TO 40
MPH DURING THE LATE MORNING AND AFTERNOON HOURS. AFTERNOON
MINIMUM RELATIVE HUMIDITY VALUES ARE EXPECTED TO BRIEFLY DROP INTO
THE 20 TO 30 PERCENT RANGE BEFORE BEGINNING A STEADY RECOVERY NEAR
SUNSET. THEREFORE...A BRIEF PERIOD OF CRITICAL FIRE WEATHER
CONDITIONS ARE POSSIBLE SATURDAY AFTERNOON...BUT HIGHLIGHTS ARE
NOT EXPECTED AT THIS TIME DUE TO THE SHORT DURATION OF LOW
RELATIVE HUMIDITY. THE MOST SUSCEPTIBLE AREAS WILL BE THE LITTLE
ROCKY MOUNTAINS AND THE MISSOURI BREAKS REGION OF ZONES 119 AND
121...WHICH WILL EXPERIENCE A RATHER POOR RELATIVE HUMIDITY
RECOVERY TONIGHT. AJZ
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM 10 AM TO 5 PM MST SATURDAY FOR FORT PECK
LAKE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 210349
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
849 PM MST FRI NOV 20 2009
.EVENING UPDATE...
FORECAST ON TRACK AND HAVE ONLY MADE A FEW MINOR ADJUSTMENTS.
SATELLITE SHOWING A LARGE TROUGH CURRENTLY MOVING ACROSS THE
PACIFIC NORTHWEST COAST AND INTO THE NORTHERN ROCKIES AREA. DEEP
SOUTHWEST FLOW ALOFT AHEAD OF THIS TROUGH IS BRINGING ABUNDANT
MID AND HIGH LEVEL CLOUDS ACROSS THE FORECAST AREA THIS EVENING.
AS A RESULT...HAVE INCREASED SKY COVER ACROSS THE AREA ESPECIALLY
THE EASTERN ZONES. MODELS HAVE SLOWED THE PROGRESSION OF THIS
TROUGH JUST A BIT WITH PRECIP NOT MAKING IT MUCH INTO OUR WESTERN
ZONES UNTIL VERY LATE TOWARD 12Z SATURDAY. AREA RADARS NOT
SHOWING ANY ACTIVITY APPROACHING AS WELL. HAVE THEREFORE TRIMMED
BACK POPS IN THE NORTHWEST AND WESTERN LOWER ELEVATION ZONES. DID
ALSO LOWER POP CHANCES JUST A BIT AS WELL FOR THE SOUTHWEST
MOUNTAINS. WINDS HAVE ALSO DECREASED QUITE A BIT IN THE
LIVINGSTON AREA SO HAVE LOWERED THESE FOR THE REMAINDER OF THE
NIGHT. TEMPERATURES ACROSS PORTIONS OF THE CENTRAL AND WEST
REMAIN IN THE 40S THIS EVENING. STILL EXPECT MIXING TO CONTINUE
THROUGHOUT THE NIGHT AND LATEST GUIDANCE COMING IN A BIT WARMER AS
WELL. SO HAVE BUMPED UP READINGS IN A FEW LOCATIONS. UPDATE OUT
SHORTLY. HOOLEY
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
WHILE THE FAIRLY BENIGN WEATHER PATTERN CONTINUES INTO THE
EXTENDED THE MODELS ARE NOT IN REAL STRONG AGREEMENT. ON MONDAY
ECMWF AND GFS ARE VERY DIFFERENT IN THE TRACK OF AN UPPER LOW
THROUGH THE AREA WITH THE ECMWF THE PREFERRED SOLUTION. GFS TRACKS
AN UPPER TROUGH ACROSS THE AREA WHILE THE ECMWF DIVES A SYSTEM
SOUTH THROUGH WYOMING. GFS HINTS AT SOME WRAP AROUND PRECIPITATION
AS THE SYSTEM AND GFS HAS BEEN TRENDING UPWARD WITH POPS SO HAVE
KEPT SOME POPS IN SOUTHEAST MONTANA AS A HEDGE...BUT GENERALLY
PREFER ECMWF SOLUTION. WILL CONTINUE COOL UNDER NORTHERLY FLOW
ALOFT THE REMAINDER OF THE DAY. TUESDAY MODELS CONTINUE TO
DISAGREE WITH A ANOTHER WAVE COMING THROUGH THE NORTHWEST FLOW
AND AMPLIFYING IT ON THE GFS WHILE THE ECMWF HAS A LIGHTER ZONAL
FLOW. SINCE THE ECMWF IS DOING A BETTER JOB OF CUTTING OFF THE
SYSTEM OVER THE PLAINS WHICH HAS BEEN THE TREND AS OF LATE. LOOKS
DRY EITHER WAY AND DO NOT STRENGTHEN WINDS AS MUCH AS GFS WOULD
INDICATE. BOTH MODELS BRING AN UPPER LEVEL RIDGE INTO THE AREA FOR
WEDNESDAY AND THURSDAY FOR TEMPERATURES 10 TO 15 DEGREES ABOVE
NORMAL AND A DOWNSLOPING WIND PATTERN. RIDGE BREAKS DOWN ON BOTH
MODELS FOR FRIDAY AND THE WEEKEND BUT AGAIN MODELS DISAGREE ON
TRACKS OF SYSTEM THROUGH THE REGION. DEFINITELY COOLER AS THE
TRANSITION OCCURS BUT NOT REALLY SURE ABOUT PRECIPITATION AT THIS
POINT. BORSUM
&&
.AVIATION...
RAIN AND SNOW SHOWERS ARE EXPECTED IN AND AROUND KLVM AND IN THE
HIGH TERRAIN BY AROUND MIDNIGHT...AS A COLD FRONT PUSHES FROM WEST
TO EAST ACROSS THE REGION OVERNIGHT. MAINLY VFR FLIGHT CONDITIONS
CAN BE EXPECTED TO PREVAIL OVER THE PLAINS. EXPECT INCREASING
CLOUDINESS OVER THE MOUNTAINS AND FOOTHILL REGION...WITH CEILINGS
DROPPING TO MVFR LEVELS AFTER MIDNIGHT. MOUNTAIN OBSCURATIONS AND
LOWER CEILINGS WILL CONTINUE THROUGH TOMORROW AFTERNOON. GILSTAD
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 034/046 024/041 026/041 025/044 026/050 031/052 031/053
03/W 02/O 22/S 11/N 10/B 00/B 01/N
LVM 031/041 022/037 018/037 024/041 025/048 030/051 029/047
24/J 04/S 31/B 12/S 10/B 00/N 02/R
HDN 028/051 024/043 024/045 023/048 023/051 023/052 024/053
02/W 02/O 22/S 12/S 20/B 00/B 01/B
MLS 026/050 024/046 024/044 021/045 022/048 025/052 027/052
02/W 02/O 21/B 12/S 20/B 00/B 01/B
4BQ 027/051 023/042 021/041 021/046 021/044 025/049 025/050
02/W 22/O 22/S 12/S 21/B 00/B 01/B
BHK 026/054 024/044 021/040 018/041 020/042 023/051 024/051
02/W 20/B 22/S 12/S 21/B 00/B 01/B
SHR 029/047 019/043 020/040 018/047 019/047 022/050 021/049
03/W 22/O 22/S 12/S 20/B 00/B 01/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KMSO 210309
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
809 PM MST FRI NOV 20 2009
.UPDATE...UPDATED EARLIER TONIGHT TO LOWER THE POPS ACROSS
NORTHWEST MONTANA FROM 00Z TO 03Z. ALSO LOWERED SOME MIN
TEMPERATURES TONIGHT.
&&
.DISCUSSION...MODELS ARE SLOWER AT BRINGING THE SYSTEM INTO
WESTERN MONTANA AND NORTH CENTRAL IDAHO TONIGHT. IN
ADDITION...SATELLITE IMAGERY AND RADARS TO OUR WEST HAS SHOWN THAT
THE SYSTEM IS MOVING SLOWER THEN EARLIER EXPECTED. SO UPDATED THE
POPS AND WEATHER FOR TONIGHT TO SHOW THE SLOWER TREND. SOME
LOCATIONS WERE AT THE FORECASTED LOW TEMPERATURE FOR TONIGHT AND
OTHERS WERE WITHIN A COUPLE OF DEGREES. MOST LOCATIONS FROM
MISSOULA NORTH NEVER WARMER UP TODAY...WITH OBSERVED HIGHS ABOUT
6 DEGREES BELOW NUMERIC GUIDANCE. SO LOWERED A NUMBER OF LOCATIONS
MAINLY ACROSS NORTHWEST MONTANA. REST OF THE FORECAST LOOKS TO BE
ON TRACK. WILL CONTINUE THE WINTER WEATHER ADVISORY FOR IDZ005-006
&&
.AVIATION...AN APPROACHING PACIFIC SYSTEM WILL CONTINUE TO
LOWER CLOUDS DECKS AND INCREASE PRECIPITATION CHANCES ACROSS THE
NORTHERN ROCKIES OVERNIGHT. AHEAD OF THE ADVANCING SURFACE COLD
FRONT...SHOWERS WILL BE A MIX OF RAIN AND SNOW BEFORE TURNING TO
ALL SNOW AFTER 21/0600Z. EXPECT THE MOST INTENSE PERIODS OF
PRECIPITATION ALONG AND JUST BEHIND THE FRONTAL PASSAGE BETWEEN
21/0600Z-21/1200Z. CEILINGS ARE EXPECTED TO LOWER OVERNIGHT
CAUSING MOUNTAINS AND PASSES TO BE OBSCURED.
&&
.PREV DISCUSSION... /ISSUED 301 PM MST FRI NOV 20 2009/
DISCUSSION...COMPLEX WEATHER PATTERN SETTING UP OVER THE
INTERMOUNTAIN REGION FOR THIS WEEKEND. BEEN AN INTERESTING DAY AS
CLOUDS AHEAD OF APPROACHING SYSTEM WERE QUITE MORE INTENSE THAN
THE MODELS HAD ADVERTISED. AS A RESULT...THE WARMING EXPECTED
TODAY WAS LIMITED TO THE SOUTHERN MOST VALLEYS (HIGHER VALLEYS)
THAT MIXED OUT EARLIER THIS MORNING AND ACHIEVED FULL MIXING
DESPITE THE CLOUDS. CENTRAL AND NORTHERN MONTANA VALLEYS WERE
INHIBITED BY THESE CLOUDS AND KEPT THE MUCH COOLER TEMPERATURES
TRAPPED IN THEIR VALLEYS. EXAMPLE...MISSOULA 37 DEGREES...HAMILTON
54 AT 230 PM MST.
THE AFOREMENTIONED WEATHER SYSTEM WILL MOVE OVER THE PACIFIC
NORTHWEST THIS EVENING SPREADING PRECIPITATION FROM WEST TO EAST
THIS EVENING AND OVERNIGHT. WARM AIR AHEAD OF THE COLD FRONT WILL
KEEP SNOW LEVELS RATHER HIGH...THEN DROPPING TO MOST VALLEY FLOORS
AFTER THE COLD FRONTAL PASSAGE AFTER MIDNIGHT. THE HIGHER VALLEYS
OF THE NORTHERN CLEARWATER MOUNTAINS LOOK TO BE THE MOST IMPACTED
BY ENOUGH ACCUMULATING SNOW TO WARRANT A WINTER HEADLINE.
THEREFORE THE WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW
ABOVE 3000 FEET WILL REMAIN IN PLACE. OTHER VALLEYS OF NORTH
CENTRAL IDAHO AND WESTERN MONTANA CAN ALSO EXPECT TO SEE SOME
LIGHT SNOW ACCUMULATIONS COME SATURDAY MORNING. AT THIS
TIME...LOOKS LIKE THE BEST TIME FRAME FOR CENTRAL AND SOUTHERN
VALLEYS OF WESTERN MONTANA TO SEE SNOW ACCUMULATIONS WILL BE 2 AM
THROUGH 9 AM...BUT NOT ENOUGH ACCUMULATIONS TO WARRANT HEADLINES.
HOWEVER...THIS SNOW WILL IMPACT ANY TRAVELERS HEADED OVER THE
CONTINENTAL DIVIDE PASSES. IN ADDITION...WINDS BEHIND THE FRONT
WILL BLOW THE SNOW AROUND AND REDUCE VISIBILITIES AT
TIMES...ESPECIALLY OVER THE PASSES.
A SECOND WEATHER SYSTEM AND ASSOCIATED SURFACE LOW WILL IMPACT THE
INTERMOUNTAIN REGION SUNDAY. THIS SYSTEM IS LOOKING MORE IMPRESSIVE
WITH EACH RUN...AND MAY BRING ANOTHER ROUND OF ACCUMULATING SNOW
TO THE CLEARWATER MOUNTAINS AND PORTIONS OF THE CAMAS
PRAIRIE...MAINLY GRANGEVILLE...GREER AND WHITEBIRD GRADES. WITH
CURRENT WINTER HEADLINES OUT...HAVE OPTED TO HOLD OFF ON A WATCH
BUT IF THE MODELS CONTINUE TO ADVERTISE THE STRENGTH AND POSITION
OF THIS SECOND SYSTEM THE WAY THEY ARE NOW...WINTER WEATHER
WATCHES MAY BE NECESSARY ONCE AGAIN. IN ADDITION...THE PLACEMENT
OF THIS SECOND WAVE LOOKS GOOD FOR PORTIONS OF WESTERN AND
SOUTHWEST MONTANA VALLEYS TO SEE ACCUMULATING SNOW TO THE VALLEY
FLOORS. AGAIN...AMOUNTS DO NOT APPEAR TO BE HEADLINE WORTHY...BUT
MAY IMPACT TRAVELERS. ANOTHER ROUND OF WIND IS EXPECTED WITH THIS
SECOND SYSTEM...SO MORE VISIBILITY ISSUES FROM BLOWING AND
DRIFTING SNOW ARE POSSIBLE.
A RIDGE OF HIGH PRESSURE WILL BEGIN TO BUILD OVER THE REGION
MONDAY WITH THE RIDGE AXIS SETTLING OVER THE REGION BY WEDNESDAY.
INITIALLY...THE RIDGE WILL BE WEAK ENOUGH TO ALLOW A FEW WEAK
DISTURBANCES TO MOVE THROUGH THE REGION BOTH MONDAY AND TUESDAY.
THE MAIN FOCUS OF PRECIPITATION IS EXPECTED TO BE ACROSS NORTHWEST
MONTANA BUT SHOULD REMAIN FAIRLY LIGHT WITH LITTLE IN THE WAY OF
ACCUMULATING SNOW. AS THE RIDGE AXIS MOVES OVERHEAD TUESDAY
NIGHT...SHOWER ACTIVITY WILL DWINDLE. WITH STRENGTHENING
INVERSIONS UNDER THIS STRONG UPPER LEVEL RIDGE...VALLEY FOG COULD
BECOME AN ISSUE WEDNESDAY AND THURSDAY. HAVE GONE AHEAD AND ADDED PATCHY
FOG TO THE FORECAST FOR THE TIME BEING BUT THE POTENTIAL FOR DENSE
FOG...POTENTIALLY IMPACTING HOLIDAY TRAVEL IS NOT OUT OF THE
QUESTION.
FORECAST MODELS INDICATE ANOTHER LOW PRESSURE TROUGH IMPACTING THE
NORTHERN ROCKIES FRIDAY IN TO NEXT WEEKEND. THE DETAILS AND TIMING OF
THIS SYSTEM REMAIN LOW FOR THE TIME BEING.
AVIATION...AN APPROACHING PACIFIC SYSTEM WILL CONTINUE TO
LOWER CLOUDS DECKS AND INCREASE PRECIPITATION CHANCES ACROSS THE
NORTHERN ROCKIES THIS EVENING AND OVERNIGHT. AHEAD OF THE ADVANCING
SURFACE COLD FRONT...SHOWERS WILL BE A MIX OF RAIN AND SNOW BEFORE
TURNING TO ALL SNOW AFTER 21/0600Z. PARTS OF NORTHWEST MONTANA AND
NORTH CENTRAL IDAHO WILL SEE SHOWER ACTIVITY START EARLIER FRIDAY
EVENING BEFORE CHANCES SPREAD ACROSS THE REMAINDER OF WESTERN
MONTANA BY 21/0600Z. EXPECT THE MOST INTENSE PERIODS OF
PRECIPITATION ALONG AND JUST BEHIND THE FRONTAL PASSAGE BETWEEN
21/0600Z-21/1200Z. CEILINGS ARE EXPECTED TO LOWER OVERNIGHT
CAUSING MOUNTAINS AND PASSES TO BE OBSCURED.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...ID...WINTER WEATHER ADVISORY UNTIL 10 AM PST SATURDAY FOR NORTHERN
CLEARWATER MOUNTAINS-SOUTHERN CLEARWATER MOUNTAINS.
&&
$$
SHORT TERM...KOLATA
LONG TERM....MEAD/PALLISTER
AVIATION...KOLATA
000
FXUS65 KTFX 202353
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
500 PM MST FRI NOV 20 2009
UPDATED AVIATION SECTION
.DISCUSSION...
AN UPPER LEVEL TROUGH OF LOW PRESSURE...CURRENTLY MOVING ONTO THE
WEST COAST...WILL TRACK EAST ACROSS THE REGION LATE TONIGHT
THROUGH EARLY SATURDAY AFTERNOON. A BRIEF PERIOD OF RIDGING BEHIND
THIS INITIAL SYSTEM SATURDAY NIGHT WILL BE QUICKLY FOLLOWED BY
ANOTHER TROUGH MOVING INTO THE NORTHERN ROCKIES ON SUNDAY. A COLD
FRONT ASSOCIATED WITH THE INITIAL TROUGH WILL MOVE EAST ACROSS THE
REGION LATE TONIGHT. MOISTURE WILL INCREASE ALONG AND BEHIND THE
FRONT WITH SNOW SHOWERS DEVELOPING AFTER MIDNIGHT OVER THE ROCKY
MTN FRONT AND GLACIER PARK AREA...SPREADING EAST OVER SW MT LATE
TONIGHT THROUGH SATURDAY MORNING. WESTERLY DOWNSLOPE FLOW WILL
LIMIT PRECIPITATION CHANCES OVER THE PLAINS...HOWEVER OCCASIONAL
SNOW SHOWERS OVER THE MTNS MAY BRING ACCUMULATIONS OF 1 TO 3
INCHES TO ELEVATIONS ABOVE 6000 FT. SIGNIFICANT COOLING WILL OCCUR
BEHIND THE FRONT OVER THE FORECAST AREA ON SATURDAY...HOWEVER THIS
WILL ONLY MEAN TEMPERATURES DROPPING BACK TO SEASONAL AVERAGES.
MODELS HAVE BEEN TRENDING SLOWER AND DEEPER WITH THE SECOND SYSTEM
TO ARRIVE ON SUNDAY AND THIS SYSTEM WILL LIKELY BRING ANOTHER
ROUND OF SNOW SHOWERS TO THE MTNS WITH PERHAPS A LITTLE BETTER
CHANCE OF SNOW SHOWERS EXTENDING FARTHER EAST ONTO THE PLAINS DUE
TO DEEPER MOISTURE AND MARGINAL INSTABILITY. ACCUMULATING SNOW
AGAIN LOOKS TO BE CONFINED MAINLY TO THE MOUNTAINOUS AREAS WITH
ANOTHER 1 TO 3 INCHES POSSIBLE ABOVE 6000 FEET. GUSTY SOUTHWEST
WINDS WILL SHIFT TO THE WEST BEHIND TONIGHTS COLD COLD FRONT WITH
WESTERN PORTIONS OF NORTH CENTRAL MT AND MTN PASSES SEEING THE
STRONGEST WINDS WITH GUSTY WINDS CONTINUING THROUGH THE WEEKEND.
COMBINATION OF GUSTY WINDS AND PERIODS OF LIGHT SNOW MAY HAVE AN
IMPACT TO TRAVELERS OVER MTN PASSES THIS WEEKEND AND WILL
HIGHLIGHT THIS IN THE HAZARDOUS WEATHER OUTLOOK. HOENISCH
SUNDAY NIGHT THROUGH FRIDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT WITH MOVING THE UPPER LEVEL TROUGH OUT OF THE AREA
SUNDAY NIGHT INTO MONDAY FOR A DECREASING CHANCE OF PRECIPITATION.
AS THE COLD FRONT ASSOCIATED WITH THIS SYSTEM ALSO MOVES THROUGH THE
AREA SUNDAY NIGHT...WEST WINDS WILL BECOME BREEZY AND GUSTY. THESE
WINDS WILL DECREASE ON MONDAY AS THE FRONT EXITS THE AREA TO THE
EAST...AS TEMPERATURES CONTINUE TO HOVER AROUND NORMAL. THE UPPER
LEVEL HIGH PRESSURE RIDGE OVER THE EASTERN PACIFIC WILL THEN BEGIN
TO BUILD BACK INTO THE WESTERN UNITED STATES MONDAY NIGHT THROUGH
TUESDAY NIGHT. HOWEVER...A WEAK SHORTWAVE WILL MOVE DOWN THE EAST
SIDE OF THE RIDGE AND THROUGH MONTANA DURING THIS TIME. THIS WILL
BRING A CHANCE OF PRECIPITATION TO THE AREA ONCE AGAIN...BUT IT WILL
MAINLY BE IN THE MOUNTAINS AS WESTERLY DOWNSLOPE WINDS WILL INCREASE
WITH THE PASSAGE OF THE SHORTWAVE. THESE WINDS WILL ALSO WARM
TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE NORMAL ON TUESDAY. THE
UPPER LEVEL RIDGE WILL THEN BUILD INTO MONTANA TUESDAY NIGHT THROUGH
THURSDAY (THANKSGIVING DAY)...WHICH WILL KEEP ONLY A SLIGHT CHANCE
OF PRECIPITATION IN THE WESTERN MONTANA MOUNTAINS. ALSO...WESTERLY
DOWNSLOPE WINDS WILL INCREASE ONCE AGAIN THROUGH THIS PERIOD...WHICH
WILL KEEP TEMPERATURES ABOUT 10 DEGREES ABOVE NORMAL. THE MODELS
BEGIN TO DIVERGE FOR THE REMAINDER OF THIS FORECAST PERIOD. THE GFS
IS MUCH FASTER THAN THE ECMWF WITH BRINGING THE NEXT PACIFIC WEATHER
SYSTEM THROUGH THE AREA. THE GFS MOVES IT THROUGH MONTANA ON
FRIDAY...WHILE THE ECMWF IS 12 TO 24 HOURS SLOWER IN MOVING IT
THROUGH FRIDAY NIGHT INTO SATURDAY. WITH THIS UNCERTAINTY...HAVE
GONE WITH A WIDESPREAD CHANCE OF PRECIPITATION FOR FRIDAY AND FRIDAY
NIGHT...WITH THE CHANCE BEING HIGHER THAN CLIMATOLOGICAL AVERAGES.
HAVE ALSO COOLED TEMPERATURES CLOSER TO NORMAL. THE INCREASES IN WIND
SUNDAY NIGHT...MONDAY NIGHT AND TUESDAY...AND THANKSGIVING DAY
INTO FRIDAY WILL NEED TO BE MONITORED FOR POSSIBLE HIGHLIGHTS.
COULSTON
&&
.AVIATION...
UPDATED 0000Z.
AN UPPER LEVEL TROF OF LOW PRESSURE WILL MOVE EASTWARD TOWARDS
CENTRAL/SOUTHWEST MONTANA LATE TONIGHT. EXPECT GENERALLY OVERCAST
CONDITIONS THROUGH THE PERIOD...WITH THE CHANCE FOR SNOW DEVELOPING
AFTER 09Z OVER WESTERN AND SOUTHWESTERN MONTANA. THE BEST CHANCE FOR
SNOW ON SATURDAY WILL BE ON SATURDAY FROM 14Z TO 20Z IN THE BOZEMAN
AND WEST YELLOWSTONE AREA. THUS IFR/LIFR CONDITIONS WILL BE POSSIBLE
AT TIMES OVER THIS REGION. MOUNTAINS WILL BE OBSCURED AT TIMES
THROUGHOUT THE REGION THOUGH THE PERIOD. ADDITIONALLY...EXPECT
SURFACE WINDS TO BECOME VERY BREEZY OVER NORTH CENTRAL MONTANA AFTER
09Z SATURDAY. BRUSDA
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 34 42 25 41 / 0 10 0 30
CTB 31 40 24 39 / 10 10 0 20
HLN 29 41 23 41 / 20 20 0 40
BZN 23 37 13 37 / 20 50 0 40
WEY 22 29 8 30 / 60 90 30 90
DLN 27 32 14 34 / 40 50 0 50
HVR 29 49 21 45 / 0 10 10 20
LWT 34 42 20 38 / 0 10 0 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HOENISCH
LONG TERM...COULSTON
AVIATION...BRUSDA
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 202215
AFDBYZ
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE BILLINGS MT
315 PM MST FRI NOV 20 2009
.SHORT TERM...VALID FOR SAT AND SUN...
CLOUDS STREAMING OVER THE REGION THIS AFTERNOON AHEAD OF THE NEXT
SYSTEM OVER THE PACIFIC NORTHWEST. SYSTEM DOES LOOK A LITTLE
SLOWER SO HAVE REMOVED POPS OVER THE MOUNTAINS THIS EVENING AND
OVER THE CENTRAL ZONES OVERNIGHT. DO THINK PRECIP WILL GET INTO
THE MOUNTAINS LATE TONIGHT SO HAVE KEPT LIKELIES IN. SYSTEM MOVES
ACROSS ON SATURDAY BUT DOES NOT HAVE A LOT OF MOISTURE OR PUNCH
WITH IT. IT ALSO MOVES ACROSS AS AN OPEN WAVE. SO DONT THINK
THERE WILL BE A WHOLE LOF OF PRECIPITATION WITH IT AND HAVE KEPT
THE PLAINS AT A SLIGHT CHANCE OR LOW CHANCE POPS. KEPT THE HIGH
POPS IN THE MOUNTAINS AS THAT WHERE THE BEST PRECIP CHANCES WILL
BE. SHOULD SEE 2 TO 4 INCHES IN THE HIGH TERRAIN FOR SATURDAY.
COLD FRONT WILL ALSO COME IN SATURDAY MORNING WITH THE TROUGH AND
BRING WINDY CONDITIONS FOR THE REGION BEHIND IT FOR MUCH OF THE
DAY. TEMPERATURES WILL ALSO BE COOLER FOR SATURDAY. SYSTEM
QUICKLY SHIFTS OUT BY SATURDAY NIGHT AS A WEAK UPPER LEVEL RIDGE
BUILDS IN. HAVE DRIED THINGS OUT FOR MOST AREAS FOR SATURDAY
NIGHT. NEXT PACIFIC SYSTEM MOVES THROUGH THE REGION SUNDAY
AFTERNOON AND NIGHT. THE GFS BRINGS THE ENERGY OVER THE FORECAST
AREA WHERE THE ECMWF DIVES THE ENERGY SOUTH. HAVE KEPT LOW POPS
FOR MOST AREAS AND HIGHER POPS OVER THE MOUNTAINS. MAY NEED SOME
HIGHER POPS FOR THE PLAINS IF THE GFS PANS OUT BUT WILL LET
FUTURE SHIFTS TAKE A LOOK AT THIS BEFORE RAISING POPS. TEMPS WILL
REMAIN FAIRLY COOL FOR SUNDAY WITH THE NEXT SYSTEM MOVING IN.
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
WHILE THE FAIRLY BENIGN WEATHER PATTERN CONTINUES INTO THE
EXTENDED THE MODELS ARE NOT IN REAL STRONG AGREEMENT. ON MONDAY
ECMWF AND GFS ARE VERY DIFFERENT IN THE TRACK OF AN UPPER LOW
THROUGH THE AREA WITH THE ECMWF THE PREFERRED SOLUTION. GFS TRACKS
AN UPPER TROUGH ACROSS THE AREA WHILE THE ECMWF DIVES A SYSTEM
SOUTH THROUGH WYOMING. GFS HINTS AT SOME WRAP AROUND PRECIPITATION
AS THE SYSTEM AND GFS HAS BEEN TRENDING UPWARD WITH POPS SO HAVE
KEPT SOME POPS IN SOUTHEAST MONTANA AS A HEDGE...BUT GENERALLY
PREFER ECMWF SOLUTION. WILL CONTINUE COOL UNDER NORTHERLY FLOW
ALOFT THE REMAINDER OF THE DAY. TUESDAY MODELS CONTINUE TO
DISAGREE WITH A ANOTHER WAVE COMING THROUGH THE NORTHWEST FLOW
AND AMPLIFYING IT ON THE GFS WHILE THE ECMWF HAS A LIGHTER ZONAL
FLOW. SINCE THE ECMWF IS DOING A BETTER JOB OF CUTTING OFF THE
SYSTEM OVER THE PLAINS WHICH HAS BEEN THE TREND AS OF LATE. LOOKS
DRY EITHER WAY AND DO NOT STRENGTHEN WINDS AS MUCH AS GFS WOULD
INDICATE. BOTH MODELS BRING AN UPPER LEVEL RIDGE INTO THE AREA FOR
WEDNESDAY AND THURSDAY FOR TEMPERATURES 10 TO 15 DEGREES ABOVE
NORMAL AND A DOWNSLOPING WIND PATTERN. RIDGE BREAKS DOWN ON BOTH
MODELS FOR FRIDAY AND THE WEEKEND BUT AGAIN MODELS DISAGREE ON
TRACKS OF SYSTEM THROUGH THE REGION. DEFINITELY COOLER AS THE
TRANSITION OCCURS BUT NOT REALLY SURE ABOUT PRECIPITATION AT THIS
POINT. BORSUM
&&
.AVIATION...
A COLD FRONT WILL MOVE FROM WEST TO EAST ACROSS THE AREA LATE
TONIGHT. EXPECT INCREASING CLOUDS WITH SHOWER ACTIVITY DEVELOPING
OVER THE MOUNTAINS AND INVOF KLVM AROUND MIDNIGHT. THIS ACTIVITY
WILL SPREAD EASTWARD SATURDAY MORNING. WINDS WILL SHIFT FROM SOUTH
WEST TO WESTERLY WHICH WILL KEEP MOST OF THE CEILINGS OVER THE
PLAINS VFR. MOUNTAIN OBSCURATIONS AND MVFR CEILINGS OVER THE
FOOTHILLS WILL DEVELOP BY 12Z AND CONTINUE UNTIL LATE AFTERNOON.
BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 032/046 024/041 026/041 025/044 026/050 031/052 031/053
03/W 02/O 22/S 11/N 10/B 00/B 01/N
LVM 029/041 022/037 018/037 024/041 025/048 030/051 029/047
34/J 04/S 31/B 12/S 10/B 00/N 02/R
HDN 028/051 024/043 024/045 023/048 023/051 023/052 024/053
02/W 02/O 22/S 12/S 20/B 00/B 01/B
MLS 026/050 024/046 024/044 021/045 022/048 025/052 027/052
02/W 02/O 21/B 12/S 20/B 00/B 01/B
4BQ 027/051 023/042 021/041 021/046 021/044 025/049 025/050
02/W 22/O 22/S 12/S 21/B 00/B 01/B
BHK 026/054 024/044 021/040 018/041 020/042 023/051 024/051
02/W 20/B 22/S 12/S 21/B 00/B 01/B
SHR 029/047 019/043 020/040 018/047 019/047 022/050 021/049
03/W 22/O 22/S 12/S 20/B 00/B 01/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KMSO 202201
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
301 PM MST FRI NOV 20 2009
.DISCUSSION...COMPLEX WEATHER PATTERN SETTING UP OVER THE
INTERMOUNTAIN REGION FOR THIS WEEKEND. BEEN AN INTERESTING DAY AS
CLOUDS AHEAD OF APPROACHING SYSTEM WERE QUITE MORE INTENSE THAN
THE MODELS HAD ADVERTISED. AS A RESULT...THE WARMING EXPECTED
TODAY WAS LIMITED TO THE SOUTHERN MOST VALLEYS (HIGHER VALLEYS)
THAT MIXED OUT EARLIER THIS MORNING AND ACHIEVED FULL MIXING
DESPITE THE CLOUDS. CENTRAL AND NORTHERN MONTANA VALLEYS WERE
INHIBITED BY THESE CLOUDS AND KEPT THE MUCH COOLER TEMPERATURES
TRAPPED IN THEIR VALLEYS. EXAMPLE...MISSOULA 37 DEGREES...HAMILTON
54 AT 230 PM MST.
THE AFOREMENTIONED WEATHER SYSTEM WILL MOVE OVER THE PACIFIC
NORTHWEST THIS EVENING SPREADING PRECIPITATION FROM WEST TO EAST
THIS EVENING AND OVERNIGHT. WARM AIR AHEAD OF THE COLD FRONT WILL
KEEP SNOW LEVELS RATHER HIGH...THEN DROPPING TO MOST VALLEY FLOORS
AFTER THE COLD FRONTAL PASSAGE AFTER MIDNIGHT. THE HIGHER VALLEYS
OF THE NORTHERN CLEARWATER MOUNTAINS LOOK TO BE THE MOST IMPACTED
BY ENOUGH ACCUMULATING SNOW TO WARRANT A WINTER HEADLINE.
THEREFORE THE WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW
ABOVE 3000 FEET WILL REMAIN IN PLACE. OTHER VALLEYS OF NORTH
CENTRAL IDAHO AND WESTERN MONTANA CAN ALSO EXPECT TO SEE SOME
LIGHT SNOW ACCUMULATIONS COME SATURDAY MORNING. AT THIS
TIME...LOOKS LIKE THE BEST TIME FRAME FOR CENTRAL AND SOUTHERN
VALLEYS OF WESTERN MONTANA TO SEE SNOW ACCUMULATIONS WILL BE 2 AM
THROUGH 9 AM...BUT NOT ENOUGH ACCUMULATIONS TO WARRANT HEADLINES.
HOWEVER...THIS SNOW WILL IMPACT ANY TRAVELERS HEADED OVER THE
CONTINENTAL DIVIDE PASSES. IN ADDITION...WINDS BEHIND THE FRONT
WILL BLOW THE SNOW AROUND AND REDUCE VISIBILITIES AT
TIMES...ESPECIALLY OVER THE PASSES.
A SECOND WEATHER SYSTEM AND ASSOCIATED SURFACE LOW WILL IMPACT THE
INTERMOUNTAIN REGION SUNDAY. THIS SYSTEM IS LOOKING MORE IMPRESSIVE
WITH EACH RUN...AND MAY BRING ANOTHER ROUND OF ACCUMULATING SNOW
TO THE CLEARWATER MOUNTAINS AND PORTIONS OF THE CAMAS
PRAIRIE...MAINLY GRANGEVILLE...GREER AND WHITEBIRD GRADES. WITH
CURRENT WINTER HEADLINES OUT...HAVE OPTED TO HOLD OFF ON A WATCH
BUT IF THE MODELS CONTINUE TO ADVERTISE THE STRENGTH AND POSITION
OF THIS SECOND SYSTEM THE WAY THEY ARE NOW...WINTER WEATHER
WATCHES MAY BE NECESSARY ONCE AGAIN. IN ADDITION...THE PLACEMENT
OF THIS SECOND WAVE LOOKS GOOD FOR PORTIONS OF WESTERN AND
SOUTHWEST MONTANA VALLEYS TO SEE ACCUMULATING SNOW TO THE VALLEY
FLOORS. AGAIN...AMOUNTS DO NOT APPEAR TO BE HEADLINE WORTHY...BUT
MAY IMPACT TRAVELERS. ANOTHER ROUND OF WIND IS EXPECTED WITH THIS
SECOND SYSTEM...SO MORE VISIBILITY ISSUES FROM BLOWING AND
DRIFTING SNOW ARE POSSIBLE.
A RIDGE OF HIGH PRESSURE WILL BEGIN TO BUILD OVER THE REGION
MONDAY WITH THE RIDGE AXIS SETTLING OVER THE REGION BY WEDNESDAY.
INITIALLY...THE RIDGE WILL BE WEAK ENOUGH TO ALLOW A FEW WEAK
DISTURBANCES TO MOVE THROUGH THE REGION BOTH MONDAY AND TUESDAY.
THE MAIN FOCUS OF PRECIPITATION IS EXPECTED TO BE ACROSS NORTHWEST
MONTANA BUT SHOULD REMAIN FAIRLY LIGHT WITH LITTLE IN THE WAY OF
ACCUMULATING SNOW. AS THE RIDGE AXIS MOVES OVERHEAD TUESDAY
NIGHT...SHOWER ACTIVITY WILL DWINDLE. WITH STRENGTHENING
INVERSIONS UNDER THIS STRONG UPPER LEVEL RIDGE...VALLEY FOG COULD
BECOME AN ISSUE WEDNESDAY AND THURSDAY. HAVE GONE AHEAD AND ADDED PATCHY
FOG TO THE FORECAST FOR THE TIME BEING BUT THE POTENTIAL FOR DENSE
FOG...POTENTIALLY IMPACTING HOLIDAY TRAVEL IS NOT OUT OF THE
QUESTION.
FORECAST MODELS INDICATE ANOTHER LOW PRESSURE TROUGH IMPACTING THE
NORTHERN ROCKIES FRIDAY IN TO NEXT WEEKEND. THE DETAILS AND TIMING OF
THIS SYSTEM REMAIN LOW FOR THE TIME BEING.
&&
.AVIATION...AN APPROACHING PACIFIC SYSTEM WILL CONTINUE TO
LOWER CLOUDS DECKS AND INCREASE PRECIPITATION CHANCES ACROSS THE
NORTHERN ROCKIES THIS EVENING AND OVERNIGHT. AHEAD OF THE ADVANCING
SURFACE COLD FRONT...SHOWERS WILL BE A MIX OF RAIN AND SNOW BEFORE
TURNING TO ALL SNOW AFTER 21/0600Z. PARTS OF NORTHWEST MONTANA AND
NORTH CENTRAL IDAHO WILL SEE SHOWER ACTIVITY START EARLIER FRIDAY
EVENING BEFORE CHANCES SPREAD ACROSS THE REMAINDER OF WESTERN
MONTANA BY 21/0600Z. EXPECT THE MOST INTENSE PERIODS OF
PRECIPITATION ALONG AND JUST BEHIND THE FRONTAL PASSAGE BETWEEN
21/0600Z-21/1200Z. CEILINGS ARE EXPECTED TO LOWER OVERNIGHT
CAUSING MOUNTAINS AND PASSES TO BE OBSCURED.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...ID...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 10 AM PST
SATURDAY FOR NORTHERN CLEARWATER MOUNTAINS-SOUTHERN
CLEARWATER MOUNTAINS.
&&
$$
SHORT TERM...MEAD
LONG TERM....PALLISTER
AVIATION...NOLTE
000
FXUS65 KBYZ 202146
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
246 PM MST FRI NOV 20 2009
.SHORT TERM...VALID FOR SAT AND SUN...
CLOUDS STREAMING OVER THE REGION THIS AFTERNOON AHEAD OF THE NEXT
SYSTEM OVER THE PACIFIC NORTHWEST. SYSTEM DOES LOOK A LITTLE
SLOWER SO HAVE REMOVED POPS OVER THE MOUNTAINS THIS EVENING AND
OVER THE CENTRAL ZONES OVERNIGHT. DO THINK PRECIP WILL GET INTO
THE MOUNTAINS LATE TONIGHT SO HAVE KEPT LIKELIES IN. SYSTEM MOVES
ACROSS ON SUNDAY BUT DOES NOT HAVE A LOT OF MOISTURE OR PUNCH
WITH IT. IT ALSO MOVES ACROSS AS AN OPEN WAVE. SO DONT THINK
THERE WILL BE A WHOLE LOF OF PRECIPITATION WITH IT AND HAVE KEPT
THE PLAINS AT A SLIGHT CHANCE OR LOW CHANCE POPS. KEPT THE HIGH
POPS IN THE MOUNTAINS AS THAT WHERE THE BEST PRECIP CHANCES WILL
BE. SHOULD SEE 2 TO 4 INCHES IN THE HIGH TERRAIN FOR SATURDAY.
COLD FRONT WILL ALSO COME IN SATURDAY MORNING WITH THE TROUGH AND
BRING WINDY CONDITIONS FOR THE REGION BEHIND IT FOR MUCH OF THE
DAY. TEMPERATURES WILL ALSO BE COOLER FOR SATURDAY. SYSTEM
QUICKLY SHIFTS OUT BY SATURDAY NIGHT AS A WEAK UPPER LEVEL RIDGE
BUILDS IN. HAVE DRIED THINGS OUT FOR MOST AREAS FOR SATURDAY
NIGHT. NEXT PACIFIC SYSTEM MOVES THROUGH THE REGION SUNDAY
AFTERNOON AND NIGHT. THE GFS BRINGS THE ENERGY OVER THE FORECAST
AREA WHERE THE ECMWF DIVES THE ENERGY SOUTH. HAVE KEPT LOW POPS
FOR MOST AREAS AND HIGHER POPS OVER THE MOUNTAINS. MAY NEED SOME
HIGHER POPS FOR THE PLAINS IF THE GFS PANS OUT BUT WILL LET
FUTURE SHIFTS TAKE A LOOK AT THIS BEFORE RAISING POPS. TEMPS WILL
REMAIN FAIRLY COOL FOR SUNDAY WITH THE NEXT SYSTEM MOVING IN.
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
WHILE THE FAIRLY BENIGN WEATHER PATTERN CONTINUES INTO THE
EXTENDED THE MODELS ARE NOT IN REAL STRONG AGREEMENT. ON MONDAY
ECMWF AND GFS ARE VERY DIFFERENT IN THE TRACK OF AN UPPER LOW
THROUGH THE AREA WITH THE ECMWF THE PREFERRED SOLUTION. GFS TRACKS
AN UPPER TROUGH ACROSS THE AREA WHILE THE ECMWF DIVES A SYSTEM
SOUTH THROUGH WYOMING. GFS HINTS AT SOME WRAP AROUND PRECIPITATION
AS THE SYSTEM AND GFS HAS BEEN TRENDING UPWARD WITH POPS SO HAVE
KEPT SOME POPS IN SOUTHEAST MONTANA AS A HEDGE...BUT GENERALLY
PREFER ECMWF SOLUTION. WILL CONTINUE COOL UNDER NORTHERLY FLOW
ALOFT THE REMAINDER OF THE DAY. TUESDAY MODELS CONTINUE TO
DISAGREE WITH A ANOTHER WAVE COMING THROUGH THE NORTHWEST FLOW
AND AMPLIFYING IT ON THE GFS WHILE THE ECMWF HAS A LIGHTER ZONAL
FLOW. SINCE THE ECMWF IS DOING A BETTER JOB OF CUTTING OFF THE
SYSTEM OVER THE PLAINS WHICH HAS BEEN THE TREND AS OF LATE. LOOKS
DRY EITHER WAY AND DO NOT STRENGTHEN WINDS AS MUCH AS GFS WOULD
INDICATE. BOTH MODELS BRING AN UPPER LEVEL RIDGE INTO THE AREA FOR
WEDNESDAY AND THURSDAY FOR TEMPERATURES 10 TO 15 DEGREES ABOVE
NORMAL AND A DOWNSLOPING WIND PATTERN. RIDGE BREAKS DOWN ON BOTH
MODELS FOR FRIDAY AND THE WEEKEND BUT AGAIN MODELS DISAGREE ON
TRACKS OF SYSTEM THROUGH THE REGION. DEFINITELY COOLER AS THE
TRANSITION OCCURS BUT NOT REALLY SURE ABOUT PRECIPITATION AT THIS
POINT. BORSUM
&&
.AVIATION...
A COLD FRONT WILL MOVE FROM WEST TO EAST ACROSS THE AREA LATE
TONIGHT. EXPECT INCREASING CLOUDS WITH SHOWER ACTIVITY DEVELOPING
OVER THE MOUNTAINS AND INVOF KLVM AROUND MIDNIGHT. THIS ACTIVITY
WILL SPREAD EASTWARD SATURDAY MORNING. WINDS WILL SHIFT FROM SOUTH
WEST TO WESTERLY WHICH WILL KEEP MOST OF THE CEILINGS OVER THE
PLAINS VFR. MOUNTAIN OBSCURATIONS AND MVFR CEILINGS OVER THE
FOOTHILLS WILL DEVELOP BY 12Z AND CONTINUE UNTIL LATE AFTERNOON.
BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 032/046 024/041 026/041 025/044 026/050 031/052 031/053
03/W 02/O 22/S 11/N 10/B 00/B 01/N
LVM 029/041 022/037 018/037 024/041 025/048 030/051 029/047
34/J 04/S 31/B 12/S 10/B 00/N 02/R
HDN 028/051 024/043 024/045 023/048 023/051 023/052 024/053
02/W 02/O 22/S 12/S 20/B 00/B 01/B
MLS 026/050 024/046 024/044 021/045 022/048 025/052 027/052
02/W 02/O 21/B 12/S 20/B 00/B 01/B
4BQ 027/051 023/042 021/041 021/046 021/044 025/049 025/050
02/W 22/O 22/S 12/S 21/B 00/B 01/B
BHK 026/054 024/044 021/040 018/041 020/042 023/051 024/051
02/W 20/B 22/S 12/S 21/B 00/B 01/B
SHR 029/047 019/043 020/040 018/047 019/047 022/050 021/049
03/W 22/O 22/S 12/S 20/B 00/B 01/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 202146
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
246 PM MST FRI NOV 20 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
AN UPPER TROUGH IS MOVING OVER THE WEST COAST THIS AFTERNOON WITH
AN UPPER RIDGE REMAINING OVER THE NORTHERN HIGH PLAINS. A COPIOUS
AMOUNT OF UPPER LEVEL PACIFIC MOISTURE IS SPILLING OVER THE
CONTINENTAL DIVIDE RESULTING IN AN EXTENSIVE AREA OF DENSE CIRRUS
CLOUDS. THE OPAQUENESS OF THIS CIRRUS HAS GENERALLY HELD
TEMPERATURES BELOW FORECAST VALUES...BUT NEVERTHELESS STILL VERY
MILD FOR THE LATER HALF OF NOVEMBER.
THE TROUGH WILL CONTINUE ITS PROGRESSION EAST TONIGHT WITH HIGH
CLOUDS CONTINUING TO STREAM OVERHEAD. LOW TEMPERATURES WILL BE ON
THE MILD SIDE...WITH A FEW OF THE LOW LYING AREAS EXPERIENCING
COLD AIR DRAINAGE AS THE WIND BECOMES LIGHT. A PACIFIC COLD FRONT
ASSOCIATED WITH THE TROUGH WILL MOVE THROUGH SATURDAY MORNING WITH
A STRONG WEST WIND DEVELOPING DURING THE LATE MORNING AND
CONTINUING THROUGH THE AFTERNOON. COLD AIR ADVECTION AND
SUBSIDENCE SHOULD SUSTAIN THE SURFACE WIND ALONG WITH STRONGER
GUSTS AS 850MB WIND SPEEDS REACH NEAR 35KT. AFTERNOON RELATIVE
HUMIDITY VALUES COULD BE RATHER LOW WITH A DOWNSLOPING WESTERLY
WIND. A SHORT PERIOD OF NEAR CRITICAL FIRE WEATHER CONDITIONS ARE
POSSIBLE. SEE THE FIRE WEATHER DISCUSSION BELOW FOR MORE
INFORMATION. THE WIND SPEED WILL EASILY MEET LAKE WIND ADVISORY
CRITERIA...SO ONE WILL BE ISSUED FOR FORT PECK LAKE.
A SHORTWAVE RIDGE CROSSES THE NORTHERN PRAIRIE SATURDAY NIGHT AND
EARLY SUNDAY BRINGING AN END TO THE WIND AND LESS CLOUD COVER. LOW
TEMPERATURES SATURDAY NIGHT COULD APPROACH SEASONAL AVERAGES UNDER
A MOSTLY CLEAR SKY. A SHORTWAVE TROUGH QUICKLY ARRIVES SUNDAY
AFTERNOON. A FEW AREAS OF LIGHT RAIN ARE POSSIBLE IN THE
AFTERNOON. SURFACE TEMPERATURES APPEAR TOO WARM FOR ANY SNOW
DURING THE AFTERNOON. AJZ
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
NO SIGNIFICANT CHANGES IN THE LONG TERM PERIOD. SEVERAL WEAK
SHORTWAVE TROFS MOVE THROUGH THE REGION...ONE SUNDAY NIGHT WITH
ANOTHER ON TUESDAY. SOME POTENTIAL FOR PRECIPITATION WITH EITHER
OF THE WAVES SO KEPT THE LOW POPS FOR THOSE PERIODS. OTHERWISE
WITH THE MORE PROGRESSIVE FLOW TEMPERATURES WILL BE CLOSER TO
NORMAL BUT STILL WARM FOR LATE NOVEMBER.
PREVIOUS LONG TERM DISCUSSION....AN UPPER SHORT-WAVE TROUGH
SWINGS THROUGH EASTERN MONTANA SUNDAY NIGHT BUT APPEARS TO KEEP
MOST ENERGY TO OUR SOUTH. THE COLD FRONT IS RATHER SUBTLE SO DO
NOT EXPECT MUCH IN THE WAY OF QPF...BUT CANNOT RULE IT OUT EITHER.
WITH 850MB TEMPERATURES AT -2*C TO -4*C ANY PRECIPITATION THAT
DOES DEVELOP WILL LIKELY BE SNOW. THE GFS AND EC DO NOT BEGIN IN
PHASE...WITH THE GFS AROUND 6-HOURS AHEAD OF THE EC. SO WILL KEEP
12-HOURS POP/WX GRIDS. THE GEM ALSO FAVORS KEEPING MOST QPF TO OUR
SOUTH BUT SUPPORTS LOW POPS FOR OUR AREA. THE PHASE DIFFERENCE
BETWEEN GFS AND EC BECOMES MORE PRONOUNCED DURING THE REMAINDER OF
THE EXTENDED PERIOD AS THE MODELS BECOME MORE PROGRESSIVE.
MONDAY/MONDAY NIGHT...THE TROUGH MOVES TO THE EAST AS AN UPPER
RIDGE/WARM FRONT MOVES OVER THE WEST. THE RIDGE WILL LIKELY BE
SHORT LIVED SINCE MODELS SHOW ANOTHER SHORT WAVE TROUGH
APPROACHING. THE GEM IS SLOWER TO EXIT ANY PRECIPITATION SO WILL
MODIFY POPS BASED ON THE UNCERTAINTY.
TUESDAY/TUESDAY NIGHT...THE 00Z GFS AND 12Z EC AGREE WITH THE
SHORT-WAVE AFFECTING THE AREA BUT DIFFER QUITE A BIT ON LOCATION
AND TIMING. THE GFS BRINGS IN THE MOISTURE DURING THE DAY WHILE
THE EC PREFERS TUESDAY NIGHT. THE 00Z EC WHICH CAME IN DURING THE
SHIFT KEPT THE MOISTURE SOUTH OF THE AREA. THE GEM BY NOW APPEARS
TO BE ON A DIFFERENT PLANET...SO WILL DISREGARD. AGAIN ANY
PRECIPITATION THAT DEVELOPS WILL LIKELY BE LIGHT AND IN THE FORM
OF SNOW OR A MIX WITH MOST 850MB TEMPERATURES NEAR OR BELOW 0*C.
SURFACE TEMPERATURES WILL LIKELY DROP MUCH CLOSER TO NORMAL.
WEDNESDAY AND BEYOND...UPPER RIDGING APPEARS TO FOLLOW...ALTHOUGH
ENSEMBLE AND OPERATIONAL PHASING AND AMPLITUDE VARY GREATLY
BETWEEN GFS AND EC. SURFACE TEMPERATURES ARE EXPECTED TO ONCE
AGAIN RISE ABOVE NORMAL...BY AROUND 10*F TO 15*F. THE NEXT SHORT
WAVE TROUGH CRASHES INTO THE NORTHWEST COAST AROUND THURSDAY...BUT
THERE CONTINUES TO BE NO CONSENSUS AS TO HOW THE TROUGH DEVELOPS
AND AFFECTS NORTHEAST MONTANA. SCT
&&
.AVIATION...
VFR CONDITIONS. SCATTERED TO BROKEN HIGH CLOUDS WILL GIVE WAY TO
INCREASING MID-LEVEL CLOUDS LATE TONIGHT AS A COLD FRONT
APPROACHES THE AREA. EAST TO SOUTHEAST WINDS OVERNIGHT WILL TURN
NORTHWEST AND INCREASE BEHIND THE FRONTAL PASSAGE DURING THE LATE
MORNING. RAE
&&
.FIRE WEATHER...
A STRONG WEST WIND WILL DEVELOP SATURDAY BEHIND A COLD FRONT.
WIND SPEEDS ARE EXPECTED TO REACH 20 TO 30 MPH...WITH GUSTS TO 40
MPH DURING THE LATE MORNING AND AFTERNOON HOURS. AFTERNOON
MINIMUM RELATIVE HUMIDITY VALUES ARE EXPECTED TO BRIEFLY DROP INTO
THE 20 TO 30 PERCENT RANGE BEFORE BEGINNING A STEADY RECOVERY NEAR
SUNSET. THEREFORE...A BRIEF PERIOD OF CRITICAL FIRE WEATHER
CONDITIONS ARE POSSIBLE SATURDAY AFTERNOON...BUT HIGHLIGHTS ARE
NOT EXPECTED AT THIS TIME DUE TO THE SHORT DURATION OF LOW
RELATIVE HUMIDITY. THE MOST SUSCEPTIBLE AREAS WILL BE THE LITTLE
ROCKY MOUNTAINS AND THE MISSOURI BREAKS REGION OF ZONES 119 AND
121...WHICH WILL EXPERIENCE A RATHER POOR RELATIVE HUMIDITY
RECOVERY TONIGHT. AJZ
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM 10 AM TO 5 PM MST SATURDAY FOR FORT PECK
LAKE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 202146
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
246 PM MST FRI NOV 20 2009
.SHORT TERM...VALID FOR SAT AND SUN...
CLOUDS STREAMING OVER THE REGION THIS AFTERNOON AHEAD OF THE NEXT
SYSTEM OVER THE PACIFIC NORTHWEST. SYSTEM DOES LOOK A LITTLE
SLOWER SO HAVE REMOVED POPS OVER THE MOUNTAINS THIS EVENING AND
OVER THE CENTRAL ZONES OVERNIGHT. DO THINK PRECIP WILL GET INTO
THE MOUNTAINS LATE TONIGHT SO HAVE KEPT LIKELIES IN. SYSTEM MOVES
ACROSS ON SUNDAY BUT DOES NOT HAVE A LOT OF MOISTURE OR PUNCH
WITH IT. IT ALSO MOVES ACROSS AS AN OPEN WAVE. SO DONT THINK
THERE WILL BE A WHOLE LOF OF PRECIPITATION WITH IT AND HAVE KEPT
THE PLAINS AT A SLIGHT CHANCE OR LOW CHANCE POPS. KEPT THE HIGH
POPS IN THE MOUNTAINS AS THAT WHERE THE BEST PRECIP CHANCES WILL
BE. SHOULD SEE 2 TO 4 INCHES IN THE HIGH TERRAIN FOR SATURDAY.
COLD FRONT WILL ALSO COME IN SATURDAY MORNING WITH THE TROUGH AND
BRING WINDY CONDITIONS FOR THE REGION BEHIND IT FOR MUCH OF THE
DAY. TEMPERATURES WILL ALSO BE COOLER FOR SATURDAY. SYSTEM
QUICKLY SHIFTS OUT BY SATURDAY NIGHT AS A WEAK UPPER LEVEL RIDGE
BUILDS IN. HAVE DRIED THINGS OUT FOR MOST AREAS FOR SATURDAY
NIGHT. NEXT PACIFIC SYSTEM MOVES THROUGH THE REGION SUNDAY
AFTERNOON AND NIGHT. THE GFS BRINGS THE ENERGY OVER THE FORECAST
AREA WHERE THE ECMWF DIVES THE ENERGY SOUTH. HAVE KEPT LOW POPS
FOR MOST AREAS AND HIGHER POPS OVER THE MOUNTAINS. MAY NEED SOME
HIGHER POPS FOR THE PLAINS IF THE GFS PANS OUT BUT WILL LET
FUTURE SHIFTS TAKE A LOOK AT THIS BEFORE RAISING POPS. TEMPS WILL
REMAIN FAIRLY COOL FOR SUNDAY WITH THE NEXT SYSTEM MOVING IN.
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
WHILE THE FAIRLY BENIGN WEATHER PATTERN CONTINUES INTO THE
EXTENDED THE MODELS ARE NOT IN REAL STRONG AGREEMENT. ON MONDAY
ECMWF AND GFS ARE VERY DIFFERENT IN THE TRACK OF AN UPPER LOW
THROUGH THE AREA WITH THE ECMWF THE PREFERRED SOLUTION. GFS TRACKS
AN UPPER TROUGH ACROSS THE AREA WHILE THE ECMWF DIVES A SYSTEM
SOUTH THROUGH WYOMING. GFS HINTS AT SOME WRAP AROUND PRECIPITATION
AS THE SYSTEM AND GFS HAS BEEN TRENDING UPWARD WITH POPS SO HAVE
KEPT SOME POPS IN SOUTHEAST MONTANA AS A HEDGE...BUT GENERALLY
PREFER ECMWF SOLUTION. WILL CONTINUE COOL UNDER NORTHERLY FLOW
ALOFT THE REMAINDER OF THE DAY. TUESDAY MODELS CONTINUE TO
DISAGREE WITH A ANOTHER WAVE COMING THROUGH THE NORTHWEST FLOW
AND AMPLIFYING IT ON THE GFS WHILE THE ECMWF HAS A LIGHTER ZONAL
FLOW. SINCE THE ECMWF IS DOING A BETTER JOB OF CUTTING OFF THE
SYSTEM OVER THE PLAINS WHICH HAS BEEN THE TREND AS OF LATE. LOOKS
DRY EITHER WAY AND DO NOT STRENGTHEN WINDS AS MUCH AS GFS WOULD
INDICATE. BOTH MODELS BRING AN UPPER LEVEL RIDGE INTO THE AREA FOR
WEDNESDAY AND THURSDAY FOR TEMPERATURES 10 TO 15 DEGREES ABOVE
NORMAL AND A DOWNSLOPING WIND PATTERN. RIDGE BREAKS DOWN ON BOTH
MODELS FOR FRIDAY AND THE WEEKEND BUT AGAIN MODELS DISAGREE ON
TRACKS OF SYSTEM THROUGH THE REGION. DEFINITELY COOLER AS THE
TRANSITION OCCURS BUT NOT REALLY SURE ABOUT PRECIPITATION AT THIS
POINT. BORSUM
&&
.AVIATION...
A COLD FRONT WILL MOVE FROM WEST TO EAST ACROSS THE AREA LATE
TONIGHT. EXPECT INCREASING CLOUDS WITH SHOWER ACTIVITY DEVELOPING
OVER THE MOUNTAINS AND INVOF KLVM AROUND MIDNIGHT. THIS ACTIVITY
WILL SPREAD EASTWARD SATURDAY MORNING. WINDS WILL SHIFT FROM SOUTH
WEST TO WESTERLY WHICH WILL KEEP MOST OF THE CEILINGS OVER THE
PLAINS VFR. MOUNTAIN OBSCURATIONS AND MVFR CEILINGS OVER THE
FOOTHILLS WILL DEVELOP BY 12Z AND CONTINUE UNTIL LATE AFTERNOON.
BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 032/046 024/041 026/041 025/044 026/050 031/052 031/053
03/W 02/O 22/S 11/N 10/B 00/B 01/N
LVM 029/041 022/037 018/037 024/041 025/048 030/051 029/047
34/J 04/S 31/B 12/S 10/B 00/N 02/R
HDN 028/051 024/043 024/045 023/048 023/051 023/052 024/053
02/W 02/O 22/S 12/S 20/B 00/B 01/B
MLS 026/050 024/046 024/044 021/045 022/048 025/052 027/052
02/W 02/O 21/B 12/S 20/B 00/B 01/B
4BQ 027/051 023/042 021/041 021/046 021/044 025/049 025/050
02/W 22/O 22/S 12/S 21/B 00/B 01/B
BHK 026/054 024/044 021/040 018/041 020/042 023/051 024/051
02/W 20/B 22/S 12/S 21/B 00/B 01/B
SHR 029/047 019/043 020/040 018/047 019/047 022/050 021/049
03/W 22/O 22/S 12/S 20/B 00/B 01/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 202146
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
246 PM MST FRI NOV 20 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY...
AN UPPER TROUGH IS MOVING OVER THE WEST COAST THIS AFTERNOON WITH
AN UPPER RIDGE REMAINING OVER THE NORTHERN HIGH PLAINS. A COPIOUS
AMOUNT OF UPPER LEVEL PACIFIC MOISTURE IS SPILLING OVER THE
CONTINENTAL DIVIDE RESULTING IN AN EXTENSIVE AREA OF DENSE CIRRUS
CLOUDS. THE OPAQUENESS OF THIS CIRRUS HAS GENERALLY HELD
TEMPERATURES BELOW FORECAST VALUES...BUT NEVERTHELESS STILL VERY
MILD FOR THE LATER HALF OF NOVEMBER.
THE TROUGH WILL CONTINUE ITS PROGRESSION EAST TONIGHT WITH HIGH
CLOUDS CONTINUING TO STREAM OVERHEAD. LOW TEMPERATURES WILL BE ON
THE MILD SIDE...WITH A FEW OF THE LOW LYING AREAS EXPERIENCING
COLD AIR DRAINAGE AS THE WIND BECOMES LIGHT. A PACIFIC COLD FRONT
ASSOCIATED WITH THE TROUGH WILL MOVE THROUGH SATURDAY MORNING WITH
A STRONG WEST WIND DEVELOPING DURING THE LATE MORNING AND
CONTINUING THROUGH THE AFTERNOON. COLD AIR ADVECTION AND
SUBSIDENCE SHOULD SUSTAIN THE SURFACE WIND ALONG WITH STRONGER
GUSTS AS 850MB WIND SPEEDS REACH NEAR 35KT. AFTERNOON RELATIVE
HUMIDITY VALUES COULD BE RATHER LOW WITH A DOWNSLOPING WESTERLY
WIND. A SHORT PERIOD OF NEAR CRITICAL FIRE WEATHER CONDITIONS ARE
POSSIBLE. SEE THE FIRE WEATHER DISCUSSION BELOW FOR MORE
INFORMATION. THE WIND SPEED WILL EASILY MEET LAKE WIND ADVISORY
CRITERIA...SO ONE WILL BE ISSUED FOR FORT PECK LAKE.
A SHORTWAVE RIDGE CROSSES THE NORTHERN PRAIRIE SATURDAY NIGHT AND
EARLY SUNDAY BRINGING AN END TO THE WIND AND LESS CLOUD COVER. LOW
TEMPERATURES SATURDAY NIGHT COULD APPROACH SEASONAL AVERAGES UNDER
A MOSTLY CLEAR SKY. A SHORTWAVE TROUGH QUICKLY ARRIVES SUNDAY
AFTERNOON. A FEW AREAS OF LIGHT RAIN ARE POSSIBLE IN THE
AFTERNOON. SURFACE TEMPERATURES APPEAR TOO WARM FOR ANY SNOW
DURING THE AFTERNOON. AJZ
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
NO SIGNIFICANT CHANGES IN THE LONG TERM PERIOD. SEVERAL WEAK
SHORTWAVE TROFS MOVE THROUGH THE REGION...ONE SUNDAY NIGHT WITH
ANOTHER ON TUESDAY. SOME POTENTIAL FOR PRECIPITATION WITH EITHER
OF THE WAVES SO KEPT THE LOW POPS FOR THOSE PERIODS. OTHERWISE
WITH THE MORE PROGRESSIVE FLOW TEMPERATURES WILL BE CLOSER TO
NORMAL BUT STILL WARM FOR LATE NOVEMBER.
PREVIOUS LONG TERM DISCUSSION....AN UPPER SHORT-WAVE TROUGH
SWINGS THROUGH EASTERN MONTANA SUNDAY NIGHT BUT APPEARS TO KEEP
MOST ENERGY TO OUR SOUTH. THE COLD FRONT IS RATHER SUBTLE SO DO
NOT EXPECT MUCH IN THE WAY OF QPF...BUT CANNOT RULE IT OUT EITHER.
WITH 850MB TEMPERATURES AT -2*C TO -4*C ANY PRECIPITATION THAT
DOES DEVELOP WILL LIKELY BE SNOW. THE GFS AND EC DO NOT BEGIN IN
PHASE...WITH THE GFS AROUND 6-HOURS AHEAD OF THE EC. SO WILL KEEP
12-HOURS POP/WX GRIDS. THE GEM ALSO FAVORS KEEPING MOST QPF TO OUR
SOUTH BUT SUPPORTS LOW POPS FOR OUR AREA. THE PHASE DIFFERENCE
BETWEEN GFS AND EC BECOMES MORE PRONOUNCED DURING THE REMAINDER OF
THE EXTENDED PERIOD AS THE MODELS BECOME MORE PROGRESSIVE.
MONDAY/MONDAY NIGHT...THE TROUGH MOVES TO THE EAST AS AN UPPER
RIDGE/WARM FRONT MOVES OVER THE WEST. THE RIDGE WILL LIKELY BE
SHORT LIVED SINCE MODELS SHOW ANOTHER SHORT WAVE TROUGH
APPROACHING. THE GEM IS SLOWER TO EXIT ANY PRECIPITATION SO WILL
MODIFY POPS BASED ON THE UNCERTAINTY.
TUESDAY/TUESDAY NIGHT...THE 00Z GFS AND 12Z EC AGREE WITH THE
SHORT-WAVE AFFECTING THE AREA BUT DIFFER QUITE A BIT ON LOCATION
AND TIMING. THE GFS BRINGS IN THE MOISTURE DURING THE DAY WHILE
THE EC PREFERS TUESDAY NIGHT. THE 00Z EC WHICH CAME IN DURING THE
SHIFT KEPT THE MOISTURE SOUTH OF THE AREA. THE GEM BY NOW APPEARS
TO BE ON A DIFFERENT PLANET...SO WILL DISREGARD. AGAIN ANY
PRECIPITATION THAT DEVELOPS WILL LIKELY BE LIGHT AND IN THE FORM
OF SNOW OR A MIX WITH MOST 850MB TEMPERATURES NEAR OR BELOW 0*C.
SURFACE TEMPERATURES WILL LIKELY DROP MUCH CLOSER TO NORMAL.
WEDNESDAY AND BEYOND...UPPER RIDGING APPEARS TO FOLLOW...ALTHOUGH
ENSEMBLE AND OPERATIONAL PHASING AND AMPLITUDE VARY GREATLY
BETWEEN GFS AND EC. SURFACE TEMPERATURES ARE EXPECTED TO ONCE
AGAIN RISE ABOVE NORMAL...BY AROUND 10*F TO 15*F. THE NEXT SHORT
WAVE TROUGH CRASHES INTO THE NORTHWEST COAST AROUND THURSDAY...BUT
THERE CONTINUES TO BE NO CONSENSUS AS TO HOW THE TROUGH DEVELOPS
AND AFFECTS NORTHEAST MONTANA. SCT
&&
.AVIATION...
VFR CONDITIONS. SCATTERED TO BROKEN HIGH CLOUDS WILL GIVE WAY TO
INCREASING MID-LEVEL CLOUDS LATE TONIGHT AS A COLD FRONT
APPROACHES THE AREA. EAST TO SOUTHEAST WINDS OVERNIGHT WILL TURN
NORTHWEST AND INCREASE BEHIND THE FRONTAL PASSAGE DURING THE LATE
MORNING. RAE
&&
.FIRE WEATHER...
A STRONG WEST WIND WILL DEVELOP SATURDAY BEHIND A COLD FRONT.
WIND SPEEDS ARE EXPECTED TO REACH 20 TO 30 MPH...WITH GUSTS TO 40
MPH DURING THE LATE MORNING AND AFTERNOON HOURS. AFTERNOON
MINIMUM RELATIVE HUMIDITY VALUES ARE EXPECTED TO BRIEFLY DROP INTO
THE 20 TO 30 PERCENT RANGE BEFORE BEGINNING A STEADY RECOVERY NEAR
SUNSET. THEREFORE...A BRIEF PERIOD OF CRITICAL FIRE WEATHER
CONDITIONS ARE POSSIBLE SATURDAY AFTERNOON...BUT HIGHLIGHTS ARE
NOT EXPECTED AT THIS TIME DUE TO THE SHORT DURATION OF LOW
RELATIVE HUMIDITY. THE MOST SUSCEPTIBLE AREAS WILL BE THE LITTLE
ROCKY MOUNTAINS AND THE MISSOURI BREAKS REGION OF ZONES 119 AND
121...WHICH WILL EXPERIENCE A RATHER POOR RELATIVE HUMIDITY
RECOVERY TONIGHT. AJZ
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
LAKE WIND ADVISORY FROM 10 AM TO 5 PM MST SATURDAY FOR FORT PECK
LAKE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 202135
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
235 PM MST FRI NOV 20 2009
.DISCUSSION...
AN UPPER LEVEL TROUGH OF LOW PRESSURE...CURRENTLY MOVING ONTO THE
WEST COAST...WILL TRACK EAST ACROSS THE REGION LATE TONIGHT
THROUGH EARLY SATURDAY AFTERNOON. A BRIEF PERIOD OF RIDGING BEHIND
THIS INITIAL SYSTEM SATURDAY NIGHT WILL BE QUICKLY FOLLOWED BY
ANOTHER TROUGH MOVING INTO THE NORTHERN ROCKIES ON SUNDAY. A COLD
FRONT ASSOCIATED WITH THE INITIAL TROUGH WILL MOVE EAST ACROSS THE
REGION LATE TONIGHT. MOISTURE WILL INCREASE ALONG AND BEHIND THE
FRONT WITH SNOW SHOWERS DEVELOPING AFTER MIDNIGHT OVER THE ROCKY
MTN FRONT AND GLACIER PARK AREA...SPREADING EAST OVER SW MT LATE
TONIGHT THROUGH SATURDAY MORNING. WESTERLY DOWNSLOPE FLOW WILL
LIMIT PRECIPITATION CHANCES OVER THE PLAINS...HOWEVER OCCASIONAL
SNOW SHOWERS OVER THE MTNS MAY BRING ACCUMULATIONS OF 1 TO 3
INCHES TO ELEVATIONS ABOVE 6000 FT. SIGNIFICANT COOLING WILL OCCUR
BEHIND THE FRONT OVER THE FORECAST AREA ON SATURDAY...HOWEVER THIS
WILL ONLY MEAN TEMPERATURES DROPPING BACK TO SEASONAL AVERAGES.
MODELS HAVE BEEN TRENDING SLOWER AND DEEPER WITH THE SECOND SYSTEM
TO ARRIVE ON SUNDAY AND THIS SYSTEM WILL LIKELY BRING ANOTHER
ROUND OF SNOW SHOWERS TO THE MTNS WITH PERHAPS A LITTLE BETTER
CHANCE OF SNOW SHOWERS EXTENDING FARTHER EAST ONTO THE PLAINS DUE
TO DEEPER MOISTURE AND MARGINAL INSTABILITY. ACCUMULATING SNOW
AGAIN LOOKS TO BE CONFINED MAINLY TO THE MOUNTAINOUS AREAS WITH
ANOTHER 1 TO 3 INCHES POSSIBLE ABOVE 6000 FEET. GUSTY SOUTHWEST
WINDS WILL SHIFT TO THE WEST BEHIND TONIGHTS COLD COLD FRONT WITH
WESTERN PORTIONS OF NORTH CENTRAL MT AND MTN PASSES SEEING THE
STRONGEST WINDS WITH GUSTY WINDS CONTINUING THROUGH THE WEEKEND.
COMBINATION OF GUSTY WINDS AND PERIODS OF LIGHT SNOW MAY HAVE AN
IMPACT TO TRAVELERS OVER MTN PASSES THIS WEEKEND AND WILL
HIGHLIGHT THIS IN THE HAZARDOUS WEATHER OUTLOOK. HOENISCH
SUNDAY NIGHT THROUGH FRIDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT WITH MOVING THE UPPER LEVEL TROUGH OUT OF THE AREA
SUNDAY NIGHT INTO MONDAY FOR A DECREASING CHANCE OF PRECIPITATION.
AS THE COLD FRONT ASSOCIATED WITH THIS SYSTEM ALSO MOVES THROUGH THE
AREA SUNDAY NIGHT...WEST WINDS WILL BECOME BREEZY AND GUSTY. THESE
WINDS WILL DECREASE ON MONDAY AS THE FRONT EXITS THE AREA TO THE
EAST...AS TEMPERATURES CONTINUE TO HOVER AROUND NORMAL. THE UPPER
LEVEL HIGH PRESSURE RIDGE OVER THE EASTERN PACIFIC WILL THEN BEGIN
TO BUILD BACK INTO THE WESTERN UNITED STATES MONDAY NIGHT THROUGH
TUESDAY NIGHT. HOWEVER...A WEAK SHORTWAVE WILL MOVE DOWN THE EAST
SIDE OF THE RIDGE AND THROUGH MONTANA DURING THIS TIME. THIS WILL
BRING A CHANCE OF PRECIPITATION TO THE AREA ONCE AGAIN...BUT IT WILL
MAINLY BE IN THE MOUNTAINS AS WESTERLY DOWNSLOPE WINDS WILL INCREASE
WITH THE PASSAGE OF THE SHORTWAVE. THESE WINDS WILL ALSO WARM
TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE NORMAL ON TUESDAY. THE
UPPER LEVEL RIDGE WILL THEN BUILD INTO MONTANA TUESDAY NIGHT THROUGH
THURSDAY (THANKSGIVING DAY)...WHICH WILL KEEP ONLY A SLIGHT CHANCE
OF PRECIPITATION IN THE WESTERN MONTANA MOUNTAINS. ALSO...WESTERLY
DOWNSLOPE WINDS WILL INCREASE ONCE AGAIN THROUGH THIS PERIOD...WHICH
WILL KEEP TEMPERATURES ABOUT 10 DEGREES ABOVE NORMAL. THE MODELS
BEGIN TO DIVERGE FOR THE REMAINDER OF THIS FORECAST PERIOD. THE GFS
IS MUCH FASTER THAN THE ECMWF WITH BRINGING THE NEXT PACIFIC WEATHER
SYSTEM THROUGH THE AREA. THE GFS MOVES IT THROUGH MONTANA ON
FRIDAY...WHILE THE ECMWF IS 12 TO 24 HOURS SLOWER IN MOVING IT
THROUGH FRIDAY NIGHT INTO SATURDAY. WITH THIS UNCERTAINTY...HAVE
GONE WITH A WIDESPREAD CHANCE OF PRECIPITATION FOR FRIDAY AND FRIDAY
NIGHT...WITH THE CHANCE BEING HIGHER THAN CLIMATOLOGICAL AVERAGES.
HAVE ALSO COOLED TEMPERATURES CLOSER TO NORMAL. THE INCREASES IN WIND
SUNDAY NIGHT...MONDAY NIGHT AND TUESDAY...AND THANKSGIVING DAY
INTO FRIDAY WILL NEED TO BE MONITORED FOR POSSIBLE HIGHLIGHTS.
COULSTON
&&
.AVIATION...
UPDATED 1800Z.
MOIST SOUTHWEST FLOW AHEAD OF AN APPROACHING PACIFIC WEATHER SYSTEM
WILL KEEP WIDESPREAD MID- AND HIGH-LEVEL CLOUDS OVER CENTRAL AND
SOUTHWEST MT TODAY AND TONIGHT. CEILINGS WILL REMAIN VFR INTO
SATURDAY MORNING. ISOLATED LIGHT VALLEY RAIN/MTN SNOW SHOWERS WILL
DEVELOP AROUND 12Z FROM KHLN TO KDLN-KBZN AS MORE MOISTURE ARRIVES
FROM THE WEST...SOME HIGHER PEAKS WILL BECOME OBSCURED NEAR
PRECIPITATION AREAS. WINDS WILL BECOME BREEZY THIS AFTN FROM KGTF
NORTHWARD TO US/CAN BORDER WITH GUSTS OF 20 TO 30 KTS. WARANAUSKAS
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 34 42 25 41 / 0 10 0 30
CTB 31 40 24 39 / 10 10 0 20
HLN 29 41 23 41 / 20 20 0 40
BZN 23 37 13 37 / 20 50 0 40
WEY 22 29 8 30 / 60 90 30 90
DLN 27 32 14 34 / 40 50 0 50
HVR 29 49 21 45 / 0 10 10 20
LWT 34 42 20 38 / 0 10 0 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HOENISCH
LONG TERM...COULSTON
AVIATION...WARANAUSKAS
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 201803
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1100 AM MST FRI NOV 20 2009
AVIATION SECTION UPDATED
.UPDATE...
SATELLITE IMAGERY THIS MORNING SHOWS PLENTY OF MID TO HIGH LEVEL
MOISTURE/CLOUD-COVER STREAMING NORTHEAST INTO THE REGION AHEAD OF
AN UPPER LEVEL TROUGH JUST COMING ONSHORE ALONG THE WEST COAST.
PRECIPITATION IS STILL WELL WEST OF THE REGION AND CLOSER TO THE
TROUGH AXIS ALONG THE WEST COAST WITH THIS PRECIPITATION EXPECTED
TO REACH THE CONTINENTAL DIVIDE BY THIS EVENING AT THE EARLIEST.
HAVE INCREASED CLOUD-COVER SOME OVER MUCH OF THE FORECAST AREA
TODAY. HAVE ALSO LOWERED MAX TEMPS SLIGHTLY OVER NORTH CENTRAL MT
DUE TO THE INCREASED CLOUD-COVER. REMAINDER OF THE FORECAST IS IN
GOOD SHAPE. HOENISCH
&&
.AVIATION...
UPDATED 1800Z.
MOIST SOUTHWEST FLOW AHEAD OF AN APPROACHING PACIFIC WEATHER SYSTEM
WILL KEEP WIDESPREAD MID- AND HIGH-LEVEL CLOUDS OVER CENTRAL AND
SOUTHWEST MT TODAY AND TONIGHT. CEILINGS WILL REMAIN VFR INTO
SATURDAY MORNING. ISOLATED LIGHT VALLEY RAIN/MTN SNOW SHOWERS WILL
DEVELOP AROUND 12Z FROM KHLN TO KDLN-KBZN AS MORE MOISTURE ARRIVES
FROM THE WEST...SOME HIGHER PEAKS WILL BECOME OBSCURED NEAR
PRECIPITATION AREAS. WINDS WILL BECOME BREEZY THIS AFTN FROM KGTF
NORTHWARD TO US/CAN BORDER WITH GUSTS OF 20 TO 30 KTS. WARANAUSKAS
&&
.PREV DISCUSSION...
/ISSUED 505 AM MST FRI NOV 20 2009/
TODAY THROUGH SUNDAY...CURRENT PROGRESSIVE PATTERN WILL CONTINUE
AS A COUPLE UPPER TROUGHS WILL BE AFFECTING THE AREA OVER THE
WEEKEND. ONE UPPER TROUGH WILL MOVE THROUGH THE AREA SATURDAY INTO
SATURDAY EVENING WITH ANOTHER UPPER TROUGH WILL MOVE INTO THE AREA
ON SUNDAY. MODELS SEEM TO INDICATE MORE MOISTURE AND LIFT WILL BE
ASSOCIATED WITH THE UPPER TROUGH ON SUNDAY SO TENDED TO GO WITH
HIGHER CHANCES OF PRECIPITATION OVER THE SOUTHWEST VALLEYS ON
SUNDAY RELATIVE TO THOSE ON SATURDAY. BOTH SYSTEMS WILL LIKELY
BRING SNOW TO THE MOUNTAINS BUT DO NOT SEE AMOUNTS WORTHY OF A
HIGHLIGHT WITH EITHER UPPER TROUGH. DOWNSLOPE SHOULD KEEP THE
PLAINS GENERALLY DRY THROUGH THE WEEKEND BUT IT DOES APPEAR THERE
COULD BE ENOUGH LIFT AND MOISTURE WITH THE SECOND UPPER TROUGH TO
WARRANT AT LEAST A SLIGHT CHANCE OF PRECIPITATION OVER THE PLAINS.
THIS WAS COVERED WELL BY THE INHERITED FORECAST. ABOVE NORMAL
TEMPERATURES WILL CONTINUE TODAY BUT TONIGHTS COLD FRONT WILL
USHER IN TEMPERATURES CLOSER TO NORMAL ON SATURDAY WHICH WILL
CONTINUE SUNDAY AS THE NEXT UPPER TROUGH MOVES INTO THE AREA.
BLANK
SUNDAY NIGHT THROUGH FRIDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT WITH MOVING THE UPPER LEVEL TROUGH OUT OF THE AREA
SUNDAY NIGHT INTO MONDAY FOR A DECREASING CHANCE OF PRECIPITATION.
AS THE COLD FRONT ASSOCIATED WITH THIS SYSTEM ALSO MOVES THROUGH THE
AREA SUNDAY NIGHT...WEST WINDS WILL BECOME BREEZY AND GUSTY. THESE
WINDS WILL DECREASE ON MONDAY AS THE FRONT EXITS THE AREA TO THE
EAST...AS TEMPERATURES CONTINUE TO HOVER AROUND NORMAL. THE UPPER
LEVEL HIGH PRESSURE RIDGE OVER THE EASTERN PACIFIC WILL THEN BEGIN
TO BUILD BACK INTO THE WESTERN UNITED STATES MONDAY NIGHT THROUGH
TUESDAY NIGHT. HOWEVER...A WEAK SHORTWAVE WILL MOVE DOWN THE EAST
SIDE OF THE RIDGE AND THROUGH MONTANA DURING THIS TIME. THIS WILL
BRING A CHANCE OF PRECIPITATION TO THE AREA ONCE AGAIN...BUT IT WILL
MAINLY BE IN THE MOUNTAINS AS WESTERLY DOWNSLOPE WINDS WILL INCREASE
WITH THE PASSAGE OF THE SHORTWAVE. THESE WINDS WILL ALSO WARM
TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE NORMAL ON TUESDAY. THE
UPPER LEVEL RIDGE WILL THEN BUILD INTO MONTANA TUESDAY NIGHT THROUGH
THURSDAY (THANKSGIVING DAY)...WHICH WILL KEEP ONLY A SLIGHT CHANCE
OF PRECIPITATION IN THE WESTERN MONTANA MOUNTAINS. ALSO...WESTERLY
DOWNSLOPE WINDS WILL INCREASE ONCE AGAIN THROUGH THIS PERIOD...WHICH
WILL KEEP TEMPERATURES ABOUT 10 DEGREES ABOVE NORMAL. THE MODELS
BEGIN TO DIVERGE FOR THE REMAINDER OF THIS FORECAST PERIOD. THE GFS
IS MUCH FASTER THAN THE ECMWF WITH BRINGING THE NEXT PACIFIC WEATHER
SYSTEM THROUGH THE AREA. THE GFS MOVES IT THROUGH MONTANA ON
FRIDAY...WHILE THE ECMWF IS 12 TO 24 HOURS SLOWER IN MOVING IT
THROUGH FRIDAY NIGHT INTO SATURDAY. WITH THIS UNCERTAINTY...HAVE
GONE WITH A WIDESPREAD CHANCE OF PRECIPITATION FOR FRIDAY AND FRIDAY
NIGHT...WITH THE CHANCE BEING HIGHER THAN CLIMATOLOGICAL AVERAGES.
HAVE ALSO COOLED TEMPERATURES CLOSER TO NORMAL. THE INCREASES IN WIND
SUNDAY NIGHT...MONDAY NIGHT AND TUESDAY...AND THANKSGIVING DAY
INTO FRIDAY WILL NEED TO BE MONITORED FOR POSSIBLE HIGHLIGHTS.
COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 56 34 43 25 / 0 10 20 10
CTB 56 32 40 24 / 0 10 10 10
HLN 52 29 41 22 / 0 30 30 10
BZN 45 21 37 7 / 0 30 50 10
WEY 41 21 29 5 / 0 50 90 30
DLN 43 24 32 11 / 0 50 50 10
HVR 60 30 48 18 / 0 0 10 0
LWT 57 33 41 19 / 0 10 10 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BLANK
LONG TERM...COULSTON
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KGGW 201652 AAA
AFDGGW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GLASGOW MT
952 AM MST FRI NOV 20 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SUNDAY...
UPPER LEVEL PACIFIC MOISTURE IS SPILLING OVER THE CONTINENTAL
DIVIDE THIS MORNING RESULTING IN CHINOOK ARCH CLOUDS EAST OF THE
ROCKIES. THE HIGH CLOUDS ARE GENERALLY THIN ONCE THEY REACH
NORTHEAST MONTANA AND ONLY PROVIDE MINIMAL OBSCURATION TO THE
SUN...SO PARTLY CLOUDY REMAINS REASONABLE FOR SKY CONDITION.
TEMPERATURES WILL BE VERY MILD FOR NOVEMBER WITH A THICKNESS RIDGE
OVER THE REGION. THE OVERALL FORECAST IS IN GOOD SHAPE WITH ONLY A
MINOR ADJUSTMENT TO SKY COVER FOR TODAY. AJZ
PREVIOUS SHORT TERM DISCUSSION...
UPPER RIDGE WILL COMBINE WITH A THERMAL RIDGE TO BRING
UNSEASONABLY WARM TEMPERATURES TO NORTHEAST MONTANA TODAY. CHINOOK
ARCH DEVELOPING ALONG THE ROCKY MOUNTAIN FRONT AT THIS TIME MAY
BRING SOME HIGH CLOUDS TO THE AREA TODAY. THE WARM AIR WILL LINGER
THROUGH TONIGHT ALLOWING FOR MILD TEMPERATURES IN MOST AREAS. WILL SEE
COLD AIR DRAINAGE IN SOME VALLEYS THAT HAVE LIGHT WINDS SIMILAR TO
THE LAST SEVERAL NIGHTS.
SHORTWAVE UPPER TROUGH CURRENTLY MOVING TOWARDS THE
WASHINGTON/OREGON COAST WILL AFFECT MONTANA ON SATURDAY. THIS WILL
BRING A COLD FRONT THROUGH EASTERN MONTANA SATURDAY MORNING. WITH
LIMITED MOISTURE MAKING IT EAST OF THE CONTINENTAL DIVIDE...THE
MAIN FEATURE WITH THE FRONT WILL BE GUSTY WEST WINDS. WILL LIKELY
NEED A LAKE WIND ADVISORY ON SATURDAY. THE RELATIVE HUMIDITIES MAY
BE LOW ENOUGH FOR FIRE WEATHER CONCERN WITH THE WIND ON SATURDAY.
WILL HOLD OFF ON A FIRE WEATHER WATCH FOR NOW.
THE UPPER TROUGH EXITS SATURDAY NIGHT AND WINDS WILL DIMINISH AS
SURFACE GRADIENT RELAXES. ANOTHER SHORTWAVE TROUGH PLOWS INTO MONTANA
ON SUNDAY WITH ANOTHER COLD FRONT. IT LOOKS LIKE IT WILL BE SUNDAY
NIGHT BEFORE THE FRONT AND SHORTWAVE REACHES EASTERN MONTANA.
WHILE TEMPERATURES WILL BE AS MUCH AS 20 DEGREES COLDER THAN
TODAY...THEY WILL STILL BE ABOVE NORMAL. SOMEWHAT BETTER MOISTURE
IS EXPECTED WITH THIS SYSTEM. WILL MENTION A SLIGHT CHANCE OF RAIN
AND SNOW IN THE SOUTHWEST FOR NOW. FORRESTER
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
AN UPPER SHORT-WAVE TROUGH SWINGS THROUGH EASTERN MONTANA SUNDAY
NIGHT BUT APPEARS TO KEEP MOST ENERGY TO OUR SOUTH. THE COLD FRONT
IS RATHER SUBTLE SO DO NOT EXPECT MUCH IN THE WAY OF QPF...BUT
CANNOT RULE IT OUT EITHER. WITH 850MB TEMPERATURES AT -2*C TO
-4*C ANY PRECIPITATION THAT DOES DEVELOP WILL LIKELY BE SNOW. THE
GFS AND EC DO NOT BEGIN IN PHASE...WITH THE GFS AROUND 6-HOURS
AHEAD OF THE EC. SO WILL KEEP 12-HOURS POP/WX GRIDS. THE GEM ALSO
FAVORS KEEPING MOST QPF TO OUR SOUTH BUT SUPPORTS LOW POPS FOR OUR
AREA. THE PHASE DIFFERENCE BETWEEN GFS AND EC BECOMES MORE
PRONOUNCED DURING THE REMAINDER OF THE EXTENDED PERIOD AS THE
MODELS BECOME MORE PROGRESSIVE.
MONDAY/MONDAY NIGHT...THE TROUGH MOVES TO THE EAST AS AN UPPER
RIDGE/WARM FRONT MOVES OVER THE WEST. THE RIDGE WILL LIKELY BE
SHORT LIVED SINCE MODELS SHOW ANOTHER SHORT WAVE TROUGH
APPROACHING. THE GEM IS SLOWER TO EXIT ANY PRECIPITATION SO WILL
MODIFY POPS BASED ON THE UNCERTAINTY.
TUESDAY/TUESDAY NIGHT...THE 00Z GFS AND 12Z EC AGREE WITH THE
SHORT-WAVE AFFECTING THE AREA BUT DIFFER QUITE A BIT ON LOCATION
AND TIMING. THE GFS BRINGS IN THE MOISTURE DURING THE DAY WHILE
THE EC PREFERS TUESDAY NIGHT. THE 00Z EC WHICH CAME IN DURING THE
SHIFT KEPT THE MOISTURE SOUTH OF THE AREA. THE GEM BY NOW APPEARS
TO BE ON A DIFFERENT PLANET...SO WILL DISREGARD. AGAIN ANY
PRECIPITATION THAT DEVELOPS WILL LIKELY BE LIGHT AND IN THE FORM
OF SNOW OR A MIX WITH MOST 850MB TEMPERATURES NEAR OR BELOW 0*C.
SURFACE TEMPERATURES WILL LIKELY DROP MUCH CLOSER TO NORMAL.
WEDNESDAY AND BEYOND...UPPER RIDGING APPEARS TO FOLLOW...ALTHOUGH
ENSEMBLE AND OPERATIONAL PHASING AND AMPLITUDE VARY GREATLY
BETWEEN GFS AND EC. SURFACE TEMPERATURES ARE EXPECTED TO ONCE
AGAIN RISE ABOVE NORMAL...BY AROUND 10*F TO 15*F. THE NEXT SHORT
WAVE TROUGH CRASHES INTO THE NORTHWEST COAST AROUND THURSDAY...BUT
THERE CONTINUES TO BE NO CONSENSUS AS TO HOW THE TROUGH DEVELOPS
AND AFFECTS NORTHEAST MONTANA. SCT
&&
.AVIATION...
VFR CONDITIONS. SCATTERED TO BROKEN HIGH CLOUDS WILL GIVE WAY TO
INCREASING MID-LEVEL CLOUDS LATE TONIGHT AS A COLD FRONT
APPROACHES THE AREA. EASTERLY TO SOUTHEASTERLY WINDS OF 5KT TO
10KT EXCEPT FOR 10KT TO 15KT NEAR KGGW. SCT
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 201643
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
943 AM MST FRI NOV 20 2009
.UPDATE...
SATELLITE IMAGERY THIS MORNING SHOWS PLENTY OF MID TO HIGH LEVEL
MOISTURE/CLOUD-COVER STREAMING NORTHEAST INTO THE REGION AHEAD OF
AN UPPER LEVEL TROUGH JUST COMING ONSHORE ALONG THE WEST COAST.
PRECIPITATION IS STILL WELL WEST OF THE REGION AND CLOSER TO THE
TROUGH AXIS ALONG THE WEST COAST WITH THIS PRECIPITATION EXPECTED
TO REACH THE CONTINENTAL DIVIDE BY THIS EVENING AT THE EARLIEST.
HAVE INCREASED CLOUD-COVER SOME OVER MUCH OF THE FORECAST AREA
TODAY. HAVE ALSO LOWERED MAX TEMPS SLIGHTLY OVER NORTH CENTRAL MT
DUE TO THE INCREASED CLOUD-COVER. REMAINDER OF THE FORECAST IS IN
GOOD SHAPE. HOENISCH
&&
.AVIATION...
UPDATED 1205Z.
VFR CONDITIONS WILL GENERALLY CONTINUE ACROSS NORTH CENTRAL...
CENTRAL...AND SOUTHWEST MONTANA THROUGH AT LEAST 12Z SATURDAY...
UNLESS OTHERWISE STATED BELOW. A MOIST SOUTHWEST FLOW ALOFT AHEAD OF
AN UPPER LEVEL LOW PRESSURE TROUGH WILL CONTINUE THE SCATTERED TO
BROKEN HIGH LEVEL CLOUDS OVER THE AREA THROUGH THIS EVENING. GUSTY
SOUTH TO SOUTHWEST WINDS WILL INCREASE THROUGH 19Z ACROSS CENTRAL
AND NORTH CENTRAL MONTANA. THE UPPER LEVEL TROUGH WILL APPROACH THE
AREA FROM THE WEST OVERNIGHT FOR AN INCREASING CHANCE OF SHOWERS IN
THE WESTERN MONTANA MOUNTAINS...WHICH WILL CAUSE SOME MOUNTAIN
OBSCURATION. COULSTON
&&
.PREV DISCUSSION...
/ISSUED 505 AM MST FRI NOV 20 2009/
TODAY THROUGH SUNDAY...CURRENT PROGRESSIVE PATTERN WILL CONTINUE
AS A COUPLE UPPER TROUGHS WILL BE AFFECTING THE AREA OVER THE
WEEKEND. ONE UPPER TROUGH WILL MOVE THROUGH THE AREA SATURDAY INTO
SATURDAY EVENING WITH ANOTHER UPPER TROUGH WILL MOVE INTO THE AREA
ON SUNDAY. MODELS SEEM TO INDICATE MORE MOISTURE AND LIFT WILL BE
ASSOCIATED WITH THE UPPER TROUGH ON SUNDAY SO TENDED TO GO WITH
HIGHER CHANCES OF PRECIPITATION OVER THE SOUTHWEST VALLEYS ON
SUNDAY RELATIVE TO THOSE ON SATURDAY. BOTH SYSTEMS WILL LIKELY
BRING SNOW TO THE MOUNTAINS BUT DO NOT SEE AMOUNTS WORTHY OF A
HIGHLIGHT WITH EITHER UPPER TROUGH. DOWNSLOPE SHOULD KEEP THE
PLAINS GENERALLY DRY THROUGH THE WEEKEND BUT IT DOES APPEAR THERE
COULD BE ENOUGH LIFT AND MOISTURE WITH THE SECOND UPPER TROUGH TO
WARRANT AT LEAST A SLIGHT CHANCE OF PRECIPITATION OVER THE PLAINS.
THIS WAS COVERED WELL BY THE INHERITED FORECAST. ABOVE NORMAL
TEMPERATURES WILL CONTINUE TODAY BUT TONIGHTS COLD FRONT WILL
USHER IN TEMPERATURES CLOSER TO NORMAL ON SATURDAY WHICH WILL
CONTINUE SUNDAY AS THE NEXT UPPER TROUGH MOVES INTO THE AREA.
BLANK
SUNDAY NIGHT THROUGH FRIDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT WITH MOVING THE UPPER LEVEL TROUGH OUT OF THE AREA
SUNDAY NIGHT INTO MONDAY FOR A DECREASING CHANCE OF PRECIPITATION.
AS THE COLD FRONT ASSOCIATED WITH THIS SYSTEM ALSO MOVES THROUGH THE
AREA SUNDAY NIGHT...WEST WINDS WILL BECOME BREEZY AND GUSTY. THESE
WINDS WILL DECREASE ON MONDAY AS THE FRONT EXITS THE AREA TO THE
EAST...AS TEMPERATURES CONTINUE TO HOVER AROUND NORMAL. THE UPPER
LEVEL HIGH PRESSURE RIDGE OVER THE EASTERN PACIFIC WILL THEN BEGIN
TO BUILD BACK INTO THE WESTERN UNITED STATES MONDAY NIGHT THROUGH
TUESDAY NIGHT. HOWEVER...A WEAK SHORTWAVE WILL MOVE DOWN THE EAST
SIDE OF THE RIDGE AND THROUGH MONTANA DURING THIS TIME. THIS WILL
BRING A CHANCE OF PRECIPITATION TO THE AREA ONCE AGAIN...BUT IT WILL
MAINLY BE IN THE MOUNTAINS AS WESTERLY DOWNSLOPE WINDS WILL INCREASE
WITH THE PASSAGE OF THE SHORTWAVE. THESE WINDS WILL ALSO WARM
TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE NORMAL ON TUESDAY. THE
UPPER LEVEL RIDGE WILL THEN BUILD INTO MONTANA TUESDAY NIGHT THROUGH
THURSDAY (THANKSGIVING DAY)...WHICH WILL KEEP ONLY A SLIGHT CHANCE
OF PRECIPITATION IN THE WESTERN MONTANA MOUNTAINS. ALSO...WESTERLY
DOWNSLOPE WINDS WILL INCREASE ONCE AGAIN THROUGH THIS PERIOD...WHICH
WILL KEEP TEMPERATURES ABOUT 10 DEGREES ABOVE NORMAL. THE MODELS
BEGIN TO DIVERGE FOR THE REMAINDER OF THIS FORECAST PERIOD. THE GFS
IS MUCH FASTER THAN THE ECMWF WITH BRINGING THE NEXT PACIFIC WEATHER
SYSTEM THROUGH THE AREA. THE GFS MOVES IT THROUGH MONTANA ON
FRIDAY...WHILE THE ECMWF IS 12 TO 24 HOURS SLOWER IN MOVING IT
THROUGH FRIDAY NIGHT INTO SATURDAY. WITH THIS UNCERTAINTY...HAVE
GONE WITH A WIDESPREAD CHANCE OF PRECIPITATION FOR FRIDAY AND FRIDAY
NIGHT...WITH THE CHANCE BEING HIGHER THAN CLIMATOLOGICAL AVERAGES.
HAVE ALSO COOLED TEMPERATURES CLOSER TO NORMAL. THE INCREASES IN WIND
SUNDAY NIGHT...MONDAY NIGHT AND TUESDAY...AND THANKSGIVING DAY
INTO FRIDAY WILL NEED TO BE MONITORED FOR POSSIBLE HIGHLIGHTS.
COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 56 34 43 25 / 0 10 20 10
CTB 56 32 40 24 / 0 10 10 10
HLN 52 29 41 22 / 0 30 30 10
BZN 45 21 37 7 / 0 30 50 10
WEY 41 21 29 5 / 0 50 90 30
DLN 43 24 32 11 / 0 50 50 10
HVR 60 30 48 18 / 0 0 10 0
LWT 57 33 41 19 / 0 10 10 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BLANK
LONG TERM...COULSTON
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KBYZ 201604
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
904 AM MST FRI NOV 20 2009
.SHORT TERM...VALID FOR TDY AND SAT...
JUST SOME MINOR TWEAKS TO THE FORECAST THIS MORNING. UPPER LEVEL
RIDGE WILL CONTINUE TO SHIFT EAST TODAY AS THE NEXT PACIFIC
SYSTEM MOVES ON SHORE. TEMPS WILL CONTINUE TO BE MILD TODAY WITH
SOME CLOUDS INCREASING MAINLY ACROSS THE WEST AS THE DAY
PROGRESSES. DRY CONDITIONS WILL CONTINUE TODAY AND THE MOUNTAINS
WILL SEE A CHANCE OF PRECIPITATION LATER ON TONIGHT. UPDATE OUT
SHORTLY. SOLUM
.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
A COUPLE OF SYSTEMS COMING DOWN THE PIPE FOR US IN THE EXTENDED
FORECAST WITH A NICE BREAK FOR THANKSGIVING. SUNDAY NIGHT INTO
MONDAY MORNING IS THE FIRST SYSTEM. THE MODELS INDICATE GOOD JET
LEVEL DIVERGENCE AND QG FORCING WITH THIS SYSTEM...BUT
NOT A VERY WELL DEFINED SURFACE FRONT. LATE SUNDAY NIGHT AND EARLY
MONDAY MORNING A LOW DEVELOPS IN NORTHEASTERN WYOMING WHICH FAVORS
PRECIPITATION FOR OUR EASTERN ZONES AND HAS GOOD UP-SLOPE INTO THE
PRYOR AND NORTH BIGHORN MOUNTAINS.
TUESDAY THE NEXT WAVE HAS WEAKER QG FORCING BUT A STRONGER LOW
LEVEL BAROCLINIC ZONE. THE QG ENERGY GIVES US A GLANCING BLOW ON
THE EASTERN ZONES WHILE THE COLDER AIRMASS BELOW MOVES NE-SW
ACROSS THE CWA. THIS PATTERN ALSO PROVIDES SOME GOOD UP-SLOPE
POTENTIAL TO THE PRIOR MOUNTAINS AN BIGHORNS AS WELL THE BEARTOOTH
MOUNTAINS. HOWEVER...THE MID AND UPPER LEVEL SUPPORT IS WEAKER FOR
THIS EVENT.
WEDNESDAY THE FLOW BECOMES ZONAL AND A LEE-SIDE TROUGH DOMINATES
THE SURFACE PATTERN. RAISED TEMPERATURES A FEW DEGREES WEDNESDAY
AND THANKSGIVING DAY IN LINE WITH GUIDANCE.
BY FRIDAY THE MODELS ARE IN COMPLETE DISAGREEMENT...HOWEVER THE
ENSEMBLE MEAN INDICATES A TROUGH MOVING TO THE NORTH OF THE CWA.
JUST RAISED POPS SLIGHTLY ABOVE CLIMATOLOGY FOR THE END OF THE PERIOD.
LEACH/HUMPHREY
&&
.AVIATION...
EXPECT INCREASING CLOUDS BUT CONTINUED VFR CONDITIONS OVER THE
AREA TODAY. SOUTHWEST FLOW ALOFT SPREADING HIGH LEVEL MOISTURE
INTO SOUTHWEST MONTANA AND WESTERN PORTIONS OF SOUTHCENTRAL
MONTANA BUT DO NOT EXPECT MOUNTAIN OBSCURATIONS TO BEGIN UNTIL
AFTER 0600Z. GUSTY WINDS WILL CONTINUE THROUGH EARLY AFTERNOON FOR
FAVORED LOCATIONS OVER THE FOOTHILLS BUT DECREASE THIS EVENING.
BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SAT SUN MON TUE WED THU
-------------------------------------------------------
BIL 060 032/046 024/041 026/041 025/044 026/050 031/052
0/B 23/W 12/S 21/B 12/S 10/B 00/B
LVM 056 029/041 022/037 018/037 024/041 025/048 030/051
0/N 34/W 13/S 21/B 12/S 10/B 00/N
HDN 061 028/051 024/043 024/048 023/048 023/051 023/052
0/B 02/W 12/O 21/B 12/S 20/B 00/B
MLS 059 026/050 024/046 024/044 021/045 022/050 025/052
0/U 02/W 21/B 21/B 12/S 20/B 00/B
4BQ 058 027/051 023/042 021/043 021/046 021/046 025/049
0/U 02/W 21/B 22/S 12/S 21/B 00/B
BHK 058 026/054 024/044 021/040 018/041 020/044 023/051
0/U 02/W 21/B 22/S 12/S 21/B 00/B
SHR 059 029/047 019/043 020/040 018/047 019/048 022/050
0/U 03/W 22/O 21/B 12/S 20/B 00/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KTFX 201207
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
505 AM MST FRI NOV 20 2009
...UPDATE TO AVIATION...
.DISCUSSION...
TODAY THROUGH SUNDAY...CURRENT PROGRESSIVE PATTERN WILL CONTINUE
AS A COUPLE UPPER TROUGHS WILL BE AFFECTING THE AREA OVER THE
WEEKEND. ONE UPPER TROUGH WILL MOVE THROUGH THE AREA SATURDAY INTO
SATURDAY EVENING WITH ANOTHER UPPER TROUGH WILL MOVE INTO THE AREA
ON SUNDAY. MODELS SEEM TO INDICATE MORE MOISTURE AND LIFT WILL BE
ASSOCIATED WITH THE UPPER TROUGH ON SUNDAY SO TENDED TO GO WITH
HIGHER CHANCES OF PRECIPITATION OVER THE SOUTHWEST VALLEYS ON
SUNDAY RELATIVE TO THOSE ON SATURDAY. BOTH SYSTEMS WILL LIKELY
BRING SNOW TO THE MOUNTAINS BUT DO NOT SEE AMOUNTS WORTHY OF A
HIGHLIGHT WITH EITHER UPPER TROUGH. DOWNSLOPE SHOULD KEEP THE
PLAINS GENERALLY DRY THROUGH THE WEEKEND BUT IT DOES APPEAR THERE
COULD BE ENOUGH LIFT AND MOISTURE WITH THE SECOND UPPER TROUGH TO
WARRANT AT LEAST A SLIGHT CHANCE OF PRECIPITATION OVER THE PLAINS.
THIS WAS COVERED WELL BY THE INHERITED FORECAST. ABOVE NORMAL
TEMPERATURES WILL CONTINUE TODAY BUT TONIGHTS COLD FRONT WILL
USHER IN TEMPERATURES CLOSER TO NORMAL ON SATURDAY WHICH WILL
CONTINUE SUNDAY AS THE NEXT UPPER TROUGH MOVES INTO THE AREA.
BLANK
SUNDAY NIGHT THROUGH FRIDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT WITH MOVING THE UPPER LEVEL TROUGH OUT OF THE AREA
SUNDAY NIGHT INTO MONDAY FOR A DECREASING CHANCE OF PRECIPITATION.
AS THE COLD FRONT ASSOCIATED WITH THIS SYSTEM ALSO MOVES THROUGH THE
AREA SUNDAY NIGHT...WEST WINDS WILL BECOME BREEZY AND GUSTY. THESE
WINDS WILL DECREASE ON MONDAY AS THE FRONT EXITS THE AREA TO THE
EAST...AS TEMPERATURES CONTINUE TO HOVER AROUND NORMAL. THE UPPER
LEVEL HIGH PRESSURE RIDGE OVER THE EASTERN PACIFIC WILL THEN BEGIN
TO BUILD BACK INTO THE WESTERN UNITED STATES MONDAY NIGHT THROUGH
TUESDAY NIGHT. HOWEVER...A WEAK SHORTWAVE WILL MOVE DOWN THE EAST
SIDE OF THE RIDGE AND THROUGH MONTANA DURING THIS TIME. THIS WILL
BRING A CHANCE OF PRECIPITATION TO THE AREA ONCE AGAIN...BUT IT WILL
MAINLY BE IN THE MOUNTAINS AS WESTERLY DOWNSLOPE WINDS WILL INCREASE
WITH THE PASSAGE OF THE SHORTWAVE. THESE WINDS WILL ALSO WARM
TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE NORMAL ON TUESDAY. THE
UPPER LEVEL RIDGE WILL THEN BUILD INTO MONTANA TUESDAY NIGHT THROUGH
THURSDAY (THANKSGIVING DAY)...WHICH WILL KEEP ONLY A SLIGHT CHANCE
OF PRECIPITATION IN THE WESTERN MONTANA MOUNTAINS. ALSO...WESTERLY
DOWNSLOPE WINDS WILL INCREASE ONCE AGAIN THROUGH THIS PERIOD...WHICH
WILL KEEP TEMPERATURES ABOUT 10 DEGREES ABOVE NORMAL. THE MODELS
BEGIN TO DIVERGE FOR THE REMAINDER OF THIS FORECAST PERIOD. THE GFS
IS MUCH FASTER THAN THE ECMWF WITH BRINGING THE NEXT PACIFIC WEATHER
SYSTEM THROUGH THE AREA. THE GFS MOVES IT THROUGH MONTANA ON
FRIDAY...WHILE THE ECMWF IS 12 TO 24 HOURS SLOWER IN MOVING IT
THROUGH FRIDAY NIGHT INTO SATURDAY. WITH THIS UNCERTAINTY...HAVE
GONE WITH A WIDESPREAD CHANCE OF PRECIPITATION FOR FRIDAY AND FRIDAY
NIGHT...WITH THE CHANCE BEING HIGHER THAN CLIMATOLOGICAL AVERAGES.
HAVE ALSO COOLED TEMPERATURES CLOSER TO NORMAL. THE INCREASES IN WIND
SUNDAY NIGHT...MONDAY NIGHT AND TUESDAY...AND THANKSGIVING DAY
INTO FRIDAY WILL NEED TO BE MONITORED FOR POSSIBLE HIGHLIGHTS.
COULSTON
&&
.AVIATION...
UPDATED 1205Z.
VFR CONDITIONS WILL GENERALLY CONTINUE ACROSS NORTH CENTRAL...
CENTRAL...AND SOUTHWEST MONTANA THROUGH AT LEAST 12Z SATURDAY...
UNLESS OTHERWISE STATED BELOW. A MOIST SOUTHWEST FLOW ALOFT AHEAD OF
AN UPPER LEVEL LOW PRESSURE TROUGH WILL CONTINUE THE SCATTERED TO
BROKEN HIGH LEVEL CLOUDS OVER THE AREA THROUGH THIS EVENING. GUSTY
SOUTH TO SOUTHWEST WINDS WILL INCREASE THROUGH 19Z ACROSS CENTRAL
AND NORTH CENTRAL MONTANA. THE UPPER LEVEL TROUGH WILL APPROACH THE
AREA FROM THE WEST OVERNIGHT FOR AN INCREASING CHANCE OF SHOWERS IN
THE WESTERN MONTANA MOUNTAINS...WHICH WILL CAUSE SOME MOUNTAIN
OBSCURATION. COULSTON
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 58 34 43 25 / 0 10 20 10
CTB 58 32 40 24 / 0 10 10 10
HLN 52 29 41 22 / 0 30 30 10
BZN 45 21 37 7 / 0 30 50 10
WEY 41 21 29 5 / 0 50 90 30
DLN 43 24 32 11 / 0 50 50 10
HVR 62 30 48 18 / 0 0 10 0
LWT 58 33 41 19 / 0 10 10 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BLANK
LONG TERM...COULSTON
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 201049
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
349 AM MST FRI NOV 20 2009
.DISCUSSION...
TODAY THROUGH SUNDAY...CURRENT PROGRESSIVE PATTERN WILL CONTINUE
AS A COUPLE UPPER TROUGHS WILL BE AFFECTING THE AREA OVER THE
WEEKEND. ONE UPPER TROUGH WILL MOVE THROUGH THE AREA SATURDAY INTO
SATURDAY EVENING WITH ANOTHER UPPER TROUGH WILL MOVE INTO THE AREA
ON SUNDAY. MODELS SEEM TO INDICATE MORE MOISTURE AND LIFT WILL BE
ASSOCIATED WITH THE UPPER TROUGH ON SUNDAY SO TENDED TO GO WITH
HIGHER CHANCES OF PRECIPITATION OVER THE SOUTHWEST VALLEYS ON
SUNDAY RELATIVE TO THOSE ON SATURDAY. BOTH SYSTEMS WILL LIKELY
BRING SNOW TO THE MOUNTAINS BUT DO NOT SEE AMOUNTS WORTHY OF A
HIGHLIGHT WITH EITHER UPPER TROUGH. DOWNSLOPE SHOULD KEEP THE
PLAINS GENERALLY DRY THROUGH THE WEEKEND BUT IT DOES APPEAR THERE
COULD BE ENOUGH LIFT AND MOISTURE WITH THE SECOND UPPER TROUGH TO
WARRANT AT LEAST A SLIGHT CHANCE OF PRECIPITATION OVER THE PLAINS.
THIS WAS COVERED WELL BY THE INHERITED FORECAST. ABOVE NORMAL
TEMPERATURES WILL CONTINUE TODAY BUT TONIGHTS COLD FRONT WILL
USHER IN TEMPERATURES CLOSER TO NORMAL ON SATURDAY WHICH WILL
CONTINUE SUNDAY AS THE NEXT UPPER TROUGH MOVES INTO THE AREA.
BLANK
SUNDAY NIGHT THROUGH FRIDAY NIGHT...THE MEDIUM RANGE MODELS ARE IN
DECENT AGREEMENT WITH MOVING THE UPPER LEVEL TROUGH OUT OF THE AREA
SUNDAY NIGHT INTO MONDAY FOR A DECREASING CHANCE OF PRECIPITATION.
AS THE COLD FRONT ASSOCIATED WITH THIS SYSTEM ALSO MOVES THROUGH THE
AREA SUNDAY NIGHT...WEST WINDS WILL BECOME BREEZY AND GUSTY. THESE
WINDS WILL DECREASE ON MONDAY AS THE FRONT EXITS THE AREA TO THE
EAST...AS TEMPERATURES CONTINUE TO HOVER AROUND NORMAL. THE UPPER
LEVEL HIGH PRESSURE RIDGE OVER THE EASTERN PACIFIC WILL THEN BEGIN
TO BUILD BACK INTO THE WESTERN UNITED STATES MONDAY NIGHT THROUGH
TUESDAY NIGHT. HOWEVER...A WEAK SHORTWAVE WILL MOVE DOWN THE EAST
SIDE OF THE RIDGE AND THROUGH MONTANA DURING THIS TIME. THIS WILL
BRING A CHANCE OF PRECIPITATION TO THE AREA ONCE AGAIN...BUT IT WILL
MAINLY BE IN THE MOUNTAINS AS WESTERLY DOWNSLOPE WINDS WILL INCREASE
WITH THE PASSAGE OF THE SHORTWAVE. THESE WINDS WILL ALSO WARM
TEMPERATURES TO ABOUT 5 TO 10 DEGREES ABOVE NORMAL ON TUESDAY. THE
UPPER LEVEL RIDGE WILL THEN BUILD INTO MONTANA TUESDAY NIGHT THROUGH
THURSDAY (THANKSGIVING DAY)...WHICH WILL KEEP ONLY A SLIGHT CHANCE
OF PRECIPITATION IN THE WESTERN MONTANA MOUNTAINS. ALSO...WESTERLY
DOWNSLOPE WINDS WILL INCREASE ONCE AGAIN THROUGH THIS PERIOD...WHICH
WILL KEEP TEMPERATURES ABOUT 10 DEGREES ABOVE NORMAL. THE MODELS
BEGIN TO DIVERGE FOR THE REMAINDER OF THIS FORECAST PERIOD. THE GFS
IS MUCH FASTER THAN THE ECMWF WITH BRINGING THE NEXT PACIFIC WEATHER
SYSTEM THROUGH THE AREA. THE GFS MOVES IT THROUGH MONTANA ON
FRIDAY...WHILE THE ECMWF IS 12 TO 24 HOURS SLOWER IN MOVING IT
THROUGH FRIDAY NIGHT INTO SATURDAY. WITH THIS UNCERTAINTY...HAVE
GONE WITH A WIDESPREAD CHANCE OF PRECIPITATION FOR FRIDAY AND FRIDAY
NIGHT...WITH THE CHANCE BEING HIGHER THAN CLIMATOLOGICAL AVERAGES.
HAVE ALSO COOLED TEMPERATURES CLOSER TO NORMAL. THE INCREASES IN WIND
SUNDAY NIGHT...MONDAY NIGHT AND TUESDAY...AND THANKSGIVING DAY
INTO FRIDAY WILL NEED TO BE MONITORED FOR POSSIBLE HIGHLIGHTS.
COULSTON
&&
.AVIATION...
UPDATED 0530Z.
SOUTHWEST FLOW ALOFT WILL CONTINUE OVER THE REGION TONIGHT THROUGH
FRIDAY EVENING. SCATTERED TO BROKEN HIGH LEVEL CLOUDS WILL STREAM
ACROSS THE FORECAST AREA THROUGH THE FORECAST PERIOD BUT EXPECT ONLY
A SLIGHT CHANCE OF SNOW SHOWERS IN THE GLACIER PARK AREA WITH DRY
CONDITIONS PREVAILING ELSEWHERE. GUSTY SOUTH TO SOUTHWEST WINDS
ACROSS NORTH CENTRAL MONTANA WILL INCREASE AGAIN BY 18Z FRIDAY THEN
ARE EXPECTED TO DIMINISH ONCE AGAIN AFTER 00Z SATURDAY. MPJ
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 58 34 43 25 / 0 10 20 10
CTB 58 32 40 24 / 0 10 10 10
HLN 52 29 41 22 / 0 30 30 10
BZN 45 21 37 7 / 0 30 50 10
WEY 41 21 29 5 / 0 50 90 30
DLN 43 24 32 11 / 0 50 50 10
HVR 62 30 48 18 / 0 0 10 0
LWT 58 33 41 19 / 0 10 10 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BLANK
LONG TERM...COULSTON
AVIATION...COULSTON
WEATHER.GOV/GREATFALLS
000
FXUS65 KMSO 201044
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
344 AM MST FRI NOV 20 2009
...ABOVE NORMAL TEMPERATURES FRIDAY...QUICKLY REPLACED BY WINTRY
CONDITIONS SATURDAY AND SUNDAY...
.DISCUSSION...A MOIST TROUGH WILL SPREAD SIGNIFICANT PRECIPITATION
INTO THE PACIFIC NORTHWEST TODAY...BUT THE NORTHERN ROCKIES WILL
SEE MAINLY HIGH CLOUDS ON THE EASTERN FRINGE OF THIS SYSTEM
THROUGH MUCH OF THE DAY. THE SOUTHERLY FLOW AHEAD OF THE TROUGH
WILL CREATE WARMER DAYTIME TEMPERATURES. BY THIS EVENING THE
TROUGH WILL MOVE EAST OF THE CASCADES...AND SPREAD VALLEY RAIN AND
MOUNTAIN SNOW THROUGHOUT NORTHERN IDAHO AND INTO FAR WESTERN
MONTANA. COOLER AIR WITH THE TROUGH WILL LOWER SNOW LEVELS TO MOST
VALLEY FLOORS LATE TONIGHT. THE MOST SIGNIFICANT SNOW
ACCUMULATIONS WILL BE OVER THE NORTHERN CLEARWATER MOUNTAINS AND
THE NORTHERN BITTERROOTS. TRAVEL IN THESE AREAS MAY BE
IMPACTED AT TIMES. A FRONT WITH THIS SYSTEM WILL CAUSE INCREASING
WINDS IN THE MOUNTAINS...AND LOCAL BLOWING SNOW WILL ALSO BE A
CONCERN. THE TROUGH WILL SLIDE EAST OF THE CONTINENTAL DIVIDE BY
SATURDAY AFTERNOON. LINGERING OROGRAPHIC LIFT AND INSTABILITY WILL
MAINTAIN MOUNTAIN SNOW SHOWERS...BUT ACCUMULATIONS WILL TAPER OFF.
A SECOND FAST MOVING TROUGH WILL PASS OVER THE NORTHERN ROCKIES
SUNDAY. MODELS ARE STILL STRUGGLING TO DEVELOP A CONSENSUS ON THE
STRENGTH OF THIS SYSTEM. IT WILL LIKELY BE AT LEAST AS GOOD A SNOW
PRODUCER AS TONIGHT`S TROUGH...PRODUCING ANOTHER 6 TO 8 INCHES IN
THE CLEARWATER MOUNTAINS AND THE BITTERROOTS. HOWEVER...THERE IS
SOME INDICATION IT MAY BE ABLE TO GENERATE UPWARDS OF A FOOT OF
NEW SNOW IN THE MOUNTAINS...BUT CONFIDENCE OF THIS IS NOT HIGH.
THE VALLEYS AND THE MOUNTAINS IN NORTHWEST MONTANA SHOULD ALSO SEE
SNOW ACCUMULATIONS WITH THIS FEATURE BUT TO A LESSER EXTENT THAN
THE BITTERROOTS AND CLEARWATERS.
MONDAY THROUGH THURSDAY...A QUICK MOVING SYSTEM WILL PASS THROUGH THE
REGION MONDAY NIGHT. AT THIS TIME IT APPEARS IT WILL BE QUICK
ENOUGH TO CAUSE MINIMAL IMPACT TO THE AREA BUT IT WILL KEEP CLOUDS
IN PLACE WHICH WILL CONTINUE TO LIMIT ANY WARMING...THUS COOLED
HIGHS ON TUESDAY A LITTLE. A RIDGE WILL ATTEMPT TO BUILD INTO THE
NORTHERN ROCKIES ON WEDNESDAY AND THURSDAY BUT A SMALL WAVE WILL
TRAVEL ALONG THE NORTHERN EDGE OF THE RIDGE KEEPING THE POTENTIAL
FOR MORE SNOWFALL ALONG THE CANADIAN BORDER. THIS KEEPS CONFIDENCE
THAT THIS RIDGE WILL ACTUALLY BUILD INTO THE AREA RATHER LOW. THE
FLOW STAYS ACTIVE WITH THE POTENTIAL OF ANOTHER SYSTEM THURSDAY
NIGHT.
&&
.AVIATION...THE NORTHERN ROCKIES WILL SEE MAINLY HIGH CLOUDS
THROUGH MUCH OF THE DAY UNDER A SOUTHERLY FLOW ALOFT. AN INCOMING
TROUGH WILL SPREAD WIDESPREAD VALLEY RAIN AND MOUNTAIN SNOW INTO
NORTHERN IDAHO THIS EVENING...THEN ACROSS WESTERN MONTANA
OVERNIGHT. SNOW LEVELS WILL LOWER TO VALLEY FLOORS OVERNIGHT AS
COLD AIR MOVES IN WITH THE TROUGH. THIS WILL CAUSE WIDESPREAD
TERRAIN OBSCURATIONS AND VISIBILITY REDUCTIONS.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...ID...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 10 AM PST
SATURDAY FOR NORTHERN CLEARWATER MOUNTAINS-SOUTHERN
CLEARWATER MOUNTAINS.
&&
$$
SHORT TERM...WHITMORE
LONG TERM....LOEFFELBEIN
AVIATION...WHITMORE
000
FXUS65 KBYZ 201008
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
308 AM MST FRI NOV 20 2009
.SHORT TERM...VALID FOR TDY AND SAT...
ANOTHER VERY MILD DAY IS IN STORE TODAY...BEFORE A SMALL COOL
DOWN THIS WEEKEND. A FLAT RIDGE WAS OVER THE STATE THIS HOUR.
QUITE A BIT OF MID TO HIGH LEVEL MOISTURE WAS STREAMING OVER THE
TOP OF THE RIDGE. HEIGHTS ARE EXPECTED TO BUILD TODAY WHILE A
TROUGH DEEPENS OVER THE WEST COAST. BUILDING HEIGHTS SHOULD PUSH
THE THICKER MID AND HIGH LEVEL CLOUDS NORTH OF THE FORECAST AREA.
AS THE FLOW BACKS...TEMPERATURES WILL RESPOND WITH INCREASING
DOWNSLOPE FLOW. HIGHS SHOULD SURGE BACK INTO THE 50S TO AROUND 60
DEGREES THIS AFTERNOON.
THE WESTERN TROUGH WILL PROGRESS EAST TODAY AND TONIGHT. THIS
WILL CAUSE HEIGHTS TO FALL TONIGHT AND SATURDAY. SOUTHWEST FLOW
WILL BRING IN MOISTURE TONIGHT AS THE TROUGH MOVES INTO THE GREAT
BASIN. MOISTURE AND DYNAMICS SHOULD HOLD OFF UNTIL TONIGHT...SO
LEFT THE DAY TODAY DRY. THE TROUGH WILL LIFT NORTHEAST INTO THE
STATE LATE TONIGHT. THE STRONGEST DYNAMICS WILL SLIDE NORTH...BUT
WEST AND SOUTHWEST FACING SLOPES WILL GET A SHOT OF ACCUMULATING
SNOW. THE TROUGH AXIS WILL MOVE INTO EASTERN MONTANA SATURDAY.
THIS WILL TAKE THE BEST Q VECTOR FORCING INTO THE DAKOTAS
SATURDAY AFTERNOON. THEREFORE...HAVE FOCUSED THE BEST POPS ON
LATE TONIGHT AND EARLY SATURDAY. THE MOUNTAINS WILL HAVE LIKELY
POPS. KEPT ACCUMULATIONS DOWN DUE TO THE PROGRESSIVE NATURE OF
FORCING AND THE LACK OF TREMENDOUS MOISTURE WITH THIS SYSTEM.
A COLD FRONT ZIPS ACROSS THE FORECAST AREA EARLY SATURDAY. THIS
WILL PROVIDE COOLER TEMPERATURES AND GUSTY WEST TO NORTHWEST
WINDS. THE FRONT WILL BE OF PACIFIC NATURE...SO NOT ANTICIPATING
A MASSIVE COOL DOWN...BUT SHOULD TAKE HIGHS LOWER BY 10 TO 15
DEGREES. CYCLONIC FLOW AND WEAK SECONDARY ENERGY BEHIND THE MAIN
TROUGH WILL KEEP THE CHANCE OF RAIN AND SNOW SHOWERS ACROSS MOST
OF THE AREA...WITH THE EMPHASIS ON THE HIGHER TERRAIN. SMALL
SCALE RIDGE IS PROGGED TO MOVE IN SATURDAY NIGHT AND THIS SHOULD
ELIMINATE THE CHANCE OF PRECIPITATION FOR ALL BUT THE MOUNTAINS.
HUMPHREY
.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
A COUPLE OF SYSTEMS COMING DOWN THE PIPE FOR US IN THE EXTENDED
FORECAST WITH A NICE BREAK FOR THANKSGIVING. SUNDAY NIGHT INTO
MONDAY MORNING IS THE FIRST SYSTEM. THE MODELS INDICATE GOOD JET
LEVEL DIVERGENCE AND QG FORCING WITH THIS SYSTEM...BUT NOT A VERY
WELL DEFINED SURFACE FRONT. LATE SUNDAY NIGHT AND EARLY MONDAY
MORNING A LOW DEVELOPS IN NORTHEASTERN WYOMING WHICH FAVORS
PRECIPITATION FOR OUR EASTERN ZONES AND HAS GOOD UP-SLOPE INTO
THE PRYOR AND NORTH BIGHORN MOUNTAINS.
TUESDAY THE NEXT WAVE HAS WEAKER QG FORCING BUT A STRONGER LOW
LEVEL BAROCLINIC ZONE. THE QG ENERGY GIVES US A GLANCING BLOW ON
THE EASTERN ZONES WHILE THE COLDER AIRMASS BELOW MOVES NE-SW
ACROSS THE CWA. THIS PATTERN ALSO PROVIDES SOME GOOD UP-SLOPE
POTENTIAL TO THE PRIOR MOUNTAINS AN BIGHORNS AS WELL THE
BEARTOOTH MOUNTAINS. HOWEVER...THE MID AND UPPER LEVEL SUPPORT IS
WEAKER FOR THIS EVENT.
WEDNESDAY THE FLOW BECOMES ZONAL AND A LEE-SIDE TROUGH DOMINATES
THE SURFACE PATTERN. RAISED TEMPERATURES A FEW DEGREES WEDNESDAY
AND THANKSGIVING DAY IN LINE WITH GUIDANCE.
BY FRIDAY THE MODELS ARE IN COMPLETE DISAGREEMENT...HOWEVER THE
ENSEMBLE MEAN INDICATES A TROUGH MOVING TO THE NORTH OF THE CWA.
JUST RAISED POPS SLIGHTLY ABOVE CLIMATOLOGY FOR THE END OF THE
PERIOD. LEACH/HUMPHREY
&&
.AVIATION...
VFR CONDITIONS ACROSS THE CWA TODAY. A DIGGING TROUGH UPSTREAM
OVER THE WASHINGTON COAST IS SPILLING MOISTURE OVER THE UPPER
LEVEL RIDGE AND OUR CWA CAUSING FEW TO SCATTERED HIGH CLOUDS. THE
HIGH CLOUDS WILL REMAIN AS THE TROUGH APPROACHES...BUT DOWN-SLOPE
CONDITIONS FROM THE SOUTHWEST FLOW WILL PREVENT ANY LOW CLOUDS.
LEE-SIDE TROUGHING AND DOWN-SLOPE FLOW WILL CONTINUE TO CAUSE
WINDY CONDITIONS EAST OF THE MOUNTAINS AND WILL MAINLY IMPACT
KLVM WITH WIND GUSTS AROUND 30 KNOTS ALL DAY FRIDAY.
LEACH/HUMPHREY
&&
.PRELIMINARY POINT TEMP/POPS...
TDY SAT SUN MON TUE WED THU
-------------------------------------------------------
BIL 060 032/046 024/041 026/041 025/044 026/050 031/052
0/B 23/W 12/S 21/B 12/S 10/B 00/B
LVM 056 029/041 022/037 018/037 024/041 025/048 030/051
0/N 34/W 13/S 21/B 12/S 10/B 00/N
HDN 061 028/051 024/043 024/048 023/048 023/051 023/052
0/B 02/W 12/O 21/B 12/S 20/B 00/B
MLS 059 026/050 024/046 024/044 021/045 022/050 025/052
0/B 02/W 21/B 21/B 12/S 20/B 00/B
4BQ 058 027/051 023/042 021/043 021/046 021/046 025/049
0/U 02/W 21/B 22/S 12/S 21/B 00/B
BHK 058 026/054 024/044 021/040 018/041 020/044 023/051
0/U 02/W 21/B 22/S 12/S 21/B 00/B
SHR 059 029/047 019/043 020/040 018/047 019/048 022/050
0/B 03/W 22/O 21/B 12/S 20/B 00/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KGGW 200946
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
246 AM MST FRI NOV 20 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TODAY THROUGH SUNDAY...
UPPER RIDGE WILL COMBINE WITH A THERMAL RIDGE TO BRING
UNSEASONABLY WARM TEMPERATURES TO NORTHEAST MONTANA TODAY. CHINOOK
ARCH DEVELOPING ALONG THE ROCKY MOUNTAIN FRONT AT THIS TIME MAY
BRING SOME HIGH CLOUDS TO THE AREA TODAY. THE WARM AIR WILL LINGER
THROUGH TONIGHT ALLOWING FOR MILD TEMPERATURES IN MOST AREAS. WILL SEE
COLD AIR DRAINAGE IN SOME VALLEYS THAT HAVE LIGHT WINDS SIMILAR TO
THE LAST SEVERAL NIGHTS.
SHORTWAVE UPPER TROUGH CURRENTLY MOVING TOWARDS THE
WASHINGTON/OREGON COAST WILL AFFECT MONTANA ON SATURDAY. THIS WILL
BRING A COLD FRONT THROUGH EASTERN MONTANA SATURDAY MORNING. WITH
LIMITED MOISTURE MAKING IT EAST OF THE CONTINENTAL DIVIDE...THE
MAIN FEATURE WITH THE FRONT WILL BE GUSTY WEST WINDS. WILL LIKELY
NEED A LAKE WIND ADVISORY ON SATURDAY. THE RELATIVE HUMIDITIES MAY
BE LOW ENOUGH FOR FIRE WEATHER CONCERN WITH THE WIND ON SATURDAY.
WILL HOLD OFF ON A FIRE WEATHER WATCH FOR NOW.
THE UPPER TROUGH EXITS SATURDAY NIGHT AND WINDS WILL DIMINISH AS
SURFACE GRADIENT RELAXES. ANOTHER SHORTWAVE TROUGH PLOWS INTO MONTANA
ON SUNDAY WITH ANOTHER COLD FRONT. IT LOOKS LIKE IT WILL BE SUNDAY
NIGHT BEFORE THE FRONT AND SHORTWAVE REACHES EASTERN MONTANA.
WHILE TEMPERATURES WILL BE AS MUCH AS 20 DEGREES COLDER THAN
TODAY...THEY WILL STILL BE ABOVE NORMAL. SOMEWHAT BETTER MOISTURE
IS EXPECTED WITH THIS SYSTEM. WILL MENTION A SLIGHT CHANCE OF RAIN
AND SNOW IN THE SOUTHWEST FOR NOW. FORRESTER
.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY...
AN UPPER SHORT-WAVE TROUGH SWINGS THROUGH EASTERN MONTANA SUNDAY
NIGHT BUT APPEARS TO KEEP MOST ENERGY TO OUR SOUTH. THE COLD FRONT
IS RATHER SUBTLE SO DO NOT EXPECT MUCH IN THE WAY OF QPF...BUT
CANNOT RULE IT OUT EITHER. WITH 850MB TEMPERATURES AT -2*C TO
-4*C ANY PRECIPITATION THAT DOES DEVELOP WILL LIKELY BE SNOW. THE
GFS AND EC DO NOT BEGIN IN PHASE...WITH THE GFS AROUND 6-HOURS
AHEAD OF THE EC. SO WILL KEEP 12-HOURS POP/WX GRIDS. THE GEM ALSO
FAVORS KEEPING MOST QPF TO OUR SOUTH BUT SUPPORTS LOW POPS FOR OUR
AREA. THE PHASE DIFFERENCE BETWEEN GFS AND EC BECOMES MORE
PRONOUNCED DURING THE REMAINDER OF THE EXTENDED PERIOD AS THE
MODELS BECOME MORE PROGRESSIVE.
MONDAY/MONDAY NIGHT...THE TROUGH MOVES TO THE EAST AS AN UPPER
RIDGE/WARM FRONT MOVES OVER THE WEST. THE RIDGE WILL LIKELY BE
SHORT LIVED SINCE MODELS SHOW ANOTHER SHORT WAVE TROUGH
APPROACHING. THE GEM IS SLOWER TO EXIT ANY PRECIPITATION SO WILL
MODIFY POPS BASED ON THE UNCERTAINTY.
TUESDAY/TUESDAY NIGHT...THE 00Z GFS AND 12Z EC AGREE WITH THE
SHORT-WAVE AFFECTING THE AREA BUT DIFFER QUITE A BIT ON LOCATION
AND TIMING. THE GFS BRINGS IN THE MOISTURE DURING THE DAY WHILE
THE EC PREFERS TUESDAY NIGHT. THE 00Z EC WHICH CAME IN DURING THE
SHIFT KEPT THE MOISTURE SOUTH OF THE AREA. THE GEM BY NOW APPEARS
TO BE ON A DIFFERENT PLANET...SO WILL DISREGARD. AGAIN ANY
PRECIPITATION THAT DEVELOPS WILL LIKELY BE LIGHT AND IN THE FORM
OF SNOW OR A MIX WITH MOST 850MB TEMPERATURES NEAR OR BELOW 0*C.
SURFACE TEMPERATURES WILL LIKELY DROP MUCH CLOSER TO NORMAL.
WEDNESDAY AND BEYOND...UPPER RIDGING APPEARS TO FOLLOW...ALTHOUGH
ENSEMBLE AND OPERATIONAL PHASING AND AMPLITUDE VARY GREATLY
BETWEEN GFS AND EC. SURFACE TEMPERATURES ARE EXPECTED TO ONCE
AGAIN RISE ABOVE NORMAL...BY AROUND 10*F TO 15*F. THE NEXT SHORT
WAVE TROUGH CRASHES INTO THE NORTHWEST COAST AROUND THURSDAY...BUT
THERE CONTINUES TO BE NO CONSENSUS AS TO HOW THE TROUGH DEVELOPS
AND AFFECTS NORTHEAST MONTANA. SCT
&&
.AVIATION...
VFR CONDITIONS. SCATTERED TO BROKEN HIGH CLOUDS WILL GIVE WAY TO
INCREASING MID-LEVEL CLOUDS LATE TONIGHT AS A COLD FRONT
APPROACHES THE AREA. EASTERLY TO SOUTHEASTERLY WINDS OF 5KT TO
10KT EXCEPT FOR 10KT TO 15KT NEAR KGGW. SCT
&&
.CLIMATE...
THROUGH THE FIRST 19 DAYS OF THE MONTH...THERE HAS BEEN NO
PRECIPITATION AT ALL AT THE GLASGOW AIRPORT. THE LAST TIME GLASGOW MADE
IT THROUGH A MONTH WITHOUT MEASURABLE PRECIPITATION WAS AUGUST
2001 WHEN ONLY A TRACE FELL. THE DRIEST NOVEMBER WAS IN 1969 WHEN
ONLY A TRACE OF PRECIPITATION FELL.
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KTFX 200530
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1030 PM MST THU NOV 19 2009
.UPDATE...
ONLY CHANGES THIS EVENING WERE TO LOWER OVERNIGHT TEMPERATURES
ACROSS SOME VALLEYS ACROSS CENTRAL AND SOUTHWEST MONTANA. HIGH CLOUDS
WILL GRADUALLY INCREASE OVERNIGHT SO INCREASED CLOUD COVER AFTER
MIDNIGHT ACROSS THE FORECAST AREA. REMAINDER OF THE FORECAST SEEMS
TO BE ON TRACK SO MADE NO FURTHER CHANGES. MLS
&&
.AVIATION...
UPDATED 0530Z.
SOUTHWEST FLOW ALOFT WILL CONTINUE OVER THE REGION TONIGHT THROUGH
FRIDAY EVENING. SCATTERED TO BROKEN HIGH LEVEL CLOUDS WILL STREAM
ACROSS THE FORECAST AREA THROUGH THE FORECAST PERIOD BUT EXPECT ONLY
A SLIGHT CHANCE OF SNOW SHOWERS IN THE GLACIER PARK AREA WITH DRY
CONDITIONS PREVAILING ELSEWHERE. GUSTY SOUTH TO SOUTHWEST WINDS
ACROSS NORTH CENTRAL MONTANA WILL INCREASE AGAIN BY 18Z FRIDAY THEN
ARE EXPECTED TO DIMINISH ONCE AGAIN AFTER 00Z SATURDAY. MPJ
&&
.PREV DISCUSSION...
/ISSUED 440 PM MST THU NOV 19 2009/
TODAY THROUGH SATURDAY EVENING...HIGH PRESSURE RIDGE STILL
IN PLACE OVER THE GREAT BASIN AND EXTENDING INTO THE NORTHERN
ROCKIES. DRY AIR UNDER THE RIDGE IS PRODUCING WIDESPREAD CLEAR
SKIES AND WARM TEMPERATURES OVER MOST OF SOUTHWEST AND CENTRAL MT
THIS AFTN. ONLY EXCEPTION IS FROM GREAT FALLS NORTHWARD TO US/CAN
BORDER WHERE CHINOOK ARCH CLOUD COVER HAS REDEVELOPED IN MOIST
SOUTHWEST FLOW ALOFT ON BACKSIDE OF THE RIDGE. OTHER THAN A SLIGHT
CHANCE FOR A STRAY SNOWSHOWER ALONG THE NORTHERN ROCKY MTN
FRONT...NO PRECIPITATION IS EXPECTED ACROSS THE REGION THIS AFTN OR
TONIGHT. SHORT-TERM MODELS SHOWING GOOD AGREEMENT AND CONSISTENCY
IN BUILDING THE RIDGE OVER MT TOMORROW IN RESPONSE TO CURRENT GULF
OF ALASKA LOW PRESSURE SYSTEM DIGGING SOUTHWARD ALONG BC/WA COAST.
LOOKS LIKE MOISTURE FROM THE PACIFIC SYSTEM WILL STAY WEST OF THE
DIVIDE UNTIL FRI NIGHT. STRENGTHENING SOUTHWEST FLOW AND SCATTERED
CLOUDS WILL PROVIDE ONE MORE DAY OF WELL-ABOVE NORMAL TEMPS TOMORROW
BEFORE SURFACE COLD FRONT ASSOCIATED WITH THE PACIFIC TROF MOVES
THROUGH CENTRAL AND SOUTHWEST MT ON SATURDAY MORNING...SHARPLY
DROPPING TEMPS ON SAT BACK TO LOW-MID 40S WHICH ARE MORE TYPICAL FOR
MID-NOVEMBER. PRECIP BECOMES WIDESPREAD ACROSS SOUTHWEST MT AND
THE ROCKY MTN FRONT SAT MORNING AND AFTN...BUT PRECIP WILL TAPER OFF
AS THE UPPER TROF MAKES STEADY PROGRESS INTO EASTERN MT BY SAT EVE.
WINDS WILL REMAIN GUSTY ACROSS WESTERN PORTIONS OF THE HILINE DOWN
TO AROUND GREAT FALLS BOTH TOMORROW AND SATURDAY AS GRADIENT BETWEEN
THE RIDGE AND APPROACHING TROF CONTINUES TO BE TIGHT THROUGH THE
PERIOD. WARANAUSKAS
SATURDAY NIGHT THROUGH TUESDAY NIGHT...MEDIUM RANGE MODELS BEGINNING
TO SHOW DIFFERENCES IN THEIR RESPECTIVE SOLUTIONS. THE GFS APPEARS
TO BE FASTER IN ITS OVERALL DEPICTIONS. THE PERIOD STARTS WITH AN
UPPER TROF EXITING THE AREA TO THE EAST AS ANOTHER UPPER TROF SWINGS
ACROSS THE PACIFIC NORTHWEST. SHOWERS OVER THE WESTERN AND SOUTHWEST
MOUNTAINS WILL DEVELOP SATURDAY NIGHT. BY SUNDAY THE UPPER TROF
CROSSES THE CONTINENTAL DIVIDE AND SCATTERED SHOWERS WILL BECOME A
BIT MORE WIDESPREAD. A POSITIVE TILT UPPER RIDGE NOSES INTO WESTERN
MONTANA MONDAY BRINGING DRIER AND A LITTLE WARMER CONDITIONS TO THE
AREA. DIFFERENCE IN MODEL SOLUTIONS SHOW UP TUESDAY AS THE EUROPEAN
MODEL IS SLOWER IN BRINGING SHORT WAVE ENERGY ACROSS THE AREA. BUT
BOTH MODELS AGREE ON A STRONGER UPPER RIDGE BUILDING OVER THE
WESTERN STATES OVERNIGHT TUESDAY. TEMPERATURES WILL CONTINUE ABOVE
SEASONAL AVERAGES.
WEDNESDAY AND THURSDAY...MODELS SHOW AN UPPER LEVEL RIDGE OVER THE
REGION ON WEDNESDAY AND THURSDAY. HOWEVER...THE RIDGE DOES FLATTEN A
BIT ON THURSDAY...IN ADVANCE OF AN UPPER LEVEL WEATHER DISTURBANCE
MOVING INTO THE PACIFIC NORTHWEST...AS PER GFS MODEL.
GFS AND ECMWF BOTH SHOW GUSTY DOWN SLOPE WINDS ON WEDNESDAY.
THE PRESSURE GRADIENT WEAKENS ON THURSDAY FOR LIGHTER WINDS...WHILE
THE ECMWF SHOW A WEAK SURFACE HIGH MOVING INTO NORTHERN MONTANA
FROM BRITISH COLUMBIA. THUS...WILL GO WITH ABOVE SEASONAL AVERAGE
TEMPERATURES BOTH DAYS...ESPECIALLY WEDNESDAY AND MOSTLY DRY
CONDITIONS OVER THE PLAINS AND VALLEYS WITH A ISOLATED/SCATTERED
SNOW SHOWERS OVER THE SOUTHWEST MOUNTAINS AND ALONG THE DIVIDE.
WILLIAMSON DC
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 30 57 30 42 / 0 0 20 20
CTB 32 58 33 40 / 0 0 20 20
HLN 24 51 26 41 / 0 0 40 50
BZN 13 54 24 36 / 0 0 40 50
WEY 3 42 22 30 / 0 0 50 90
DLN 19 45 25 31 / 0 0 60 50
HVR 32 62 29 48 / 0 0 10 10
LWT 26 55 29 41 / 0 0 10 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KTFX 200440
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
940 PM MST THU NOV 19 2009
.UPDATE...
ONLY CHANGES THIS EVENING WERE TO LOWER OVERNIGHT TEMPERATURES
ACROSS SOME VALLEYS ACROSS CENTRAL AND SOUTHWEST MONTANA. HIGH CLOUDS
WILL GRADUALLY INCREASE OVERNIGHT SO INCREASED CLOUD COVER AFTER
MIDNIGHT ACROSS THE FORECAST AREA. REMAINDER OF THE FORECAST SEEMS
TO BE ON TRACK SO MADE NO FURTHER CHANGES. MLS
&&
.AVIATION...
UPDATED 2340Z.
SOUTHWEST FLOW ALOFT WILL CONTINUE OVER THE REGION TONIGHT THROUGH
FRIDAY AFTERNOON. MID AND HIGH LEVEL CLOUDS WILL STREAM ACROSS THE
FORECAST AREA THIS EVENING BUT EXPECT ONLY A SLIGHT CHANCE OF SNOW
SHOWERS IN THE GLACIER PARK AREA WITH DRY CONDITIONS PREVAILING
ELSEWHERE. GUSTY SOUTH TO SOUTHWEST WINDS ACROSS NORTH CENTRAL
MONTANA WILL DIMINISH BY 02Z BUT ARE EXPECTED TO INCREASE AGAIN BY
18Z FRIDAY. MPJ
&&
.PREV DISCUSSION...
/ISSUED 440 PM MST THU NOV 19 2009/
TODAY THROUGH SATURDAY EVENING...HIGH PRESSURE RIDGE STILL
IN PLACE OVER THE GREAT BASIN AND EXTENDING INTO THE NORTHERN
ROCKIES. DRY AIR UNDER THE RIDGE IS PRODUCING WIDESPREAD CLEAR
SKIES AND WARM TEMPERATURES OVER MOST OF SOUTHWEST AND CENTRAL MT
THIS AFTN. ONLY EXCEPTION IS FROM GREAT FALLS NORTHWARD TO US/CAN
BORDER WHERE CHINOOK ARCH CLOUD COVER HAS REDEVELOPED IN MOIST
SOUTHWEST FLOW ALOFT ON BACKSIDE OF THE RIDGE. OTHER THAN A SLIGHT
CHANCE FOR A STRAY SNOWSHOWER ALONG THE NORTHERN ROCKY MTN
FRONT...NO PRECIPITATION IS EXPECTED ACROSS THE REGION THIS AFTN OR
TONIGHT. SHORT-TERM MODELS SHOWING GOOD AGREEMENT AND CONSISTENCY
IN BUILDING THE RIDGE OVER MT TOMORROW IN RESPONSE TO CURRENT GULF
OF ALASKA LOW PRESSURE SYSTEM DIGGING SOUTHWARD ALONG BC/WA COAST.
LOOKS LIKE MOISTURE FROM THE PACIFIC SYSTEM WILL STAY WEST OF THE
DIVIDE UNTIL FRI NIGHT. STRENGTHENING SOUTHWEST FLOW AND SCATTERED
CLOUDS WILL PROVIDE ONE MORE DAY OF WELL-ABOVE NORMAL TEMPS TOMORROW
BEFORE SURFACE COLD FRONT ASSOCIATED WITH THE PACIFIC TROF MOVES THROUGH
CENTRAL AND SOUTHWEST MT ON SATURDAY MORNING...SHARPLY DROPPING
TEMPS ON SAT BACK TO LOW-MID 40S WHICH ARE MORE TYPICAL FOR
MID-NOVEMBER. PRECIP BECOMES WIDESPREAD ACROSS SOUTHWEST MT AND
THE ROCKY MTN FRONT SAT MORNING AND AFTN...BUT PRECIP WILL TAPER OFF
AS THE UPPER TROF MAKES STEADY PROGRESS INTO EASTERN MT BY SAT EVE.
WINDS WILL REMAIN GUSTY ACROSS WESTERN PORTIONS OF THE HILINE DOWN
TO AROUND GREAT FALLS BOTH TOMORROW AND SATURDAY AS GRADIENT BETWEEN
THE RIDGE AND APPROACHING TROF CONTINUES TO BE TIGHT THROUGH THE
PERIOD. WARANAUSKAS
SATURDAY NIGHT THROUGH TUESDAY NIGHT...MEDIUM RANGE MODELS BEGINNING
TO SHOW DIFFERENCES IN THEIR RESPECTIVE SOLUTIONS. THE GFS APPEARS
TO BE FASTER IN ITS OVERALL DEPICTIONS. THE PERIOD STARTS WITH AN
UPPER TROF EXITING THE AREA TO THE EAST AS ANOTHER UPPER TROF SWINGS
ACROSS THE PACIFIC NORTHWEST. SHOWERS OVER THE WESTERN AND SOUTHWEST
MOUNTAINS WILL DEVELOP SATURDAY NIGHT. BY SUNDAY THE UPPER TROF
CROSSES THE CONTINENTAL DIVIDE AND SCATTERED SHOWERS WILL BECOME A
BIT MORE WIDESPREAD. A POSITIVE TILT UPPER RIDGE NOSES INTO WESTERN
MONTANA MONDAY BRINGING DRIER AND A LITTLE WARMER CONDITIONS TO THE
AREA. DIFFERENCE IN MODEL SOLUTIONS SHOW UP TUESDAY AS THE EUROPEAN
MODEL IS SLOWER IN BRINGING SHORT WAVE ENERGY ACROSS THE AREA. BUT
BOTH MODELS AGREE ON A STRONGER UPPER RIDGE BUILDING OVER THE
WESTERN STATES OVERNIGHT TUESDAY. TEMPERATURES WILL CONTINUE ABOVE
SEASONAL AVERAGES.
WEDNESDAY AND THURSDAY...MODELS SHOW AN UPPER LEVEL RIDGE OVER THE
REGION ON WEDNESDAY AND THURSDAY. HOWEVER...THE RIDGE DOES FLATTEN A
BIT ON THURSDAY...IN ADVANCE OF AN UPPER LEVEL WEATHER DISTURBANCE
MOVING INTO THE PACIFIC NORTHWEST...AS PER GFS MODEL.
GFS AND ECMWF BOTH SHOW GUSTY DOWN SLOPE WINDS ON WEDNESDAY.
THE PRESSURE GRADIENT WEAKENS ON THURSDAY FOR LIGHTER WINDS...WHILE
THE ECMWF SHOW A WEAK SURFACE HIGH MOVING INTO NORTHERN MONTANA
FROM BRITISH COLUMBIA. THUS...WILL GO WITH ABOVE SEASONAL AVERAGE
TEMPERATURES BOTH DAYS...ESPECIALLY WEDNESDAY AND MOSTLY DRY
CONDITIONS OVER THE PLAINS AND VALLEYS WITH A ISOLATED/SCATTERED
SNOW SHOWERS OVER THE SOUTHWEST MOUNTAINS AND ALONG THE DIVIDE.
WILLIAMSON DC
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 30 57 30 42 / 0 0 20 20
CTB 32 58 33 40 / 0 0 20 20
HLN 24 51 26 41 / 0 0 40 50
BZN 13 54 24 36 / 0 0 40 50
WEY 3 42 22 30 / 0 0 50 90
DLN 19 45 25 31 / 0 0 60 50
HVR 32 62 29 48 / 0 0 10 10
LWT 26 55 29 41 / 0 0 10 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
WEATHER.GOV/GREATFALLS
000
FXUS65 KGGW 200353
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
853 PM MST THU NOV 19 2009
.SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SATURDAY...
HIGH CHINOOK ARCH TYPE CLOUDS HAVE BEEN GREATER THAN ANTICIPATED.
WATER VAPOR AND GFS PROGGED 250 MB MOISTURE SHOWING IT TO CONTINUE
MOVING IN THROUGH FRIDAY MORNING. THEREFORE INCREASED CLOUDS INTO
FRIDAY MORNING. REST OF FORECAST LOOKED GOOD. JAMBA
PREVIOUS DISCUSSION...
THE CURRENT LONGWAVE PATTERN OVER NORTH AMERICA FEATURES A BROAD
HIGH AMPLITUDE RIDGE OVER THE EASTERN TWO THIRDS OF THE CONTINENT
WITH A CLOSED LOW SITUATED SOUTH OF THE RIDGE OVER THE GREAT LAKES
REGION. CURRENT GOES WATER VAPOR IMAGERY REVEALS A VIGOROUS TROUGH
DRIVING ACROSS THE EAST PACIFIC. THIS TROUGH WILL PROGRESS EAST
AND AFFECT NORTHEAST MONTANA BY SATURDAY AS THE HIGHLY BLOCKED
PATTERN OVER EASTERN NORTH AMERICA STEADILY SUBSIDES.
PLEASANT CONDITIONS WILL PRECEDE THE APPROACH OF THE TROUGH AS
HIGH PRESSURE ALOFT REMAINS THE DOMINANT FEATURE. LIGHT WIND
SPEEDS OVERNIGHT WILL ALLOW FOR COLD AIR DRAINAGE IN THE VALLEYS
RESULTING IN SEASONABLY COOL LOW TEMPERATURES WITH WARMER READINGS
AT HIGHER ELEVATIONS...ESPECIALLY WITH THE COMMENCEMENT OF WARM
AIR ADVECTION. THE WARM ADVECTION RESULTS IN A THERMAL RIDGE OVER
THE LOCAL AREA FRIDAY WITH SOUTHERLY FLOW AS A LEE-SIDE SURFACE
TROUGH DEVELOPS OVER CENTRAL MONTANA. SIMILAR WIND AND THERMAL
PATTERNS HAVE RESULTED IN MILD DAYS IN THE RECENT PAST...SO
TEMPERATURES WERE RAISED A FEW DEGREES...AND ARE ALSO WELL ABOVE
MOS.
THE AFOREMENTIONED TROUGH AND ASSOCIATED COLD FRONT REACH THE AREA
SATURDAY. COLD AIR ADVECTION AND SUBSIDENCE SHOULD ALLOW THE WIND
TO GET RATHER EXCITED LATE SATURDAY MORNING AND AFTERNOON. A
WESTERLY DIRECTION WILL ALLOW FOR A STRONG DOWNSLOPE COMPONENT
RESULTING IN LOW RELATIVE HUMIDITY VALUES ACROSS THE REGION. THE
COMBINATION OF A STRONG WIND AND LOW RELATIVE HUMIDITY COULD
CREATE FIRE WEATHER CONCERNS SATURDAY AFTERNOON. AJZ
.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...
THE EXTENDED PERIODS BEGINS WITH A SERIES OF SHORTWAVE TROUGHS WEST
OF THE REGION...WHICH WILL MOVE ACROSS MONTANA OVER THE WEEKEND.
THE FIRST SHORTWAVE IS LOCATED OVER OVER WESTERN MONTANA SATURDAY
EVENING. IT WAS RESPONSIBLE FOR PUSHING A COLD FRONT INTO THE
DAKOTAS EARLY DURING THE DAY. THE LATEST MODEL RUNS CONTINUE TO
KEEP THE ENERGY AND LIFT ASSOCIATED WITH THIS WAVE SOUTH OF THE
REGION...ALONG WITH ANY PRECIPITATION. LEFT THE FORECAST DRY
DURING THIS PERIOD.
ANOTHER SHORTWAVE QUICKLY FOLLOWS SUNDAY AFTERNOON AND SUNDAY
NIGHT. THINGS HAVE CHANGED SOMEWHAT WITH THE SECOND WAVE IN THE
LATEST MODELS RUNS. THE CANADIAN...GFS AND ECMWF MODELS OVER THE
LAST FEW RUNS WERE KEEPING THE ENERGY/QPF ASSOCIATED WITH THE
SECOND SHORTWAVE SOUTH OF THE REGION. THE NEW 00Z GFS AND ECMWF
STILL HAVE THE MAJORITY OF ENERGY SOUTH OF THE REGION BUT NOW ARE
ALSO SHOWING SOME ENERGY/QPF ACROSS NORTHERN MONTANA. THE 00Z
CANADIAN REMAINS DRY AS IT STILL SHOWS THE ENERGY AND QPF PASSING
SOUTH OF THE REGION. THIS PUT A LITTLE UNCERTAINTY IN THE FORECAST
FOR SUNDAY EVENING THROUGH MONDAY MORNING. SINCE WE TOOK THE
PRECIPITATION OUT OF THE FORECAST FOR THIS TIME FRAME YESTERDAY...AND
SINCE THE 00Z RUNS WERE THE FIRST RUNS TO ADD THE PRECIPITATION
BACK TO NORTHERN MONTANA. I WILL CONTINUE TO KEEP THE ZONES DRY
FOR NOW...AND LET A FEW MORE MODEL RUNS COME OUT BEFORE JUMPING
BACK ON THE SLIGHT CHANCE OF PRECIPITATION FOR SUNDAY NIGHT BANDWAGON.
I DID INCREASE THE POPS FOR THIS PERIOD UP TO 14 AND JUST UNDER THE
SLIGHT CHANCE. IF THE PRECIPITATION WERE TO HAPPEN IT WOULD LIKELY BE
IN THE FORM OF LIGHT SNOW. THE SHORTWAVE IS A LITTLE SLOWER ON
THE ECMWF THEN IT IS ON THE GFS SO IT MIGHT LINGER INTO MONDAY
AFTERNOON WHICH WOULD KEEP THINGS A LITTLE COOLER ON MONDAY. KEPT
HIGH IN THE LOWER 40S TO REFLECT THIS SINCE WE ARE LIKELY TO
MAINTAIN CLOUD COVER MOST OF THE DAY.
MONDAY NIGHT AND BEYOND... MODELS BEGIN TO LOSE PHASE BY 24 HOURS DURING
THIS PERIOD WITHE GFS BEING THE FASTER MODEL AND ECMWF BEING THE
SLOWER MODEL. BOTH SHOW A SHORTWAVE WITH EMBEDDED PRECIPITATION
MOVING THROUGH THE REGION SOME TIME MONDAY NIGHT THROUGH TUESDAY
NIGHT. FOR NOW... HAVE TAKEN A MODERATED APPROACH WITH TUESDAY
BEING THE PERIOD THAT RECEIVES RAIN DUE TO THE CLIPPER SYSTEM.
WEDNESDAY ONWARD A UPPER LEVEL RIDGE IS ANTICIPATED TO MOVE INTO THE
REGION GENERATING FURTHER CLEAR SKIES AND DRY CONDITIONS. GHICKS/RSMITH
&&
.AVIATION...
VFR CONDITIONS WILL CONTINUE THROUGH TONIGHT WITH BROKEN HIGH CLOUD
COVER. WINDS WILL BE LIGHT AND VARIABLE TONIGHT...EXCEPT FOR
SOUTHEASTERLY WINDS OF AROUND 10KT NEAR KGGW. GAH/SCT
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
WEATHER.GOV/GLASGOW
000
FXUS65 KBYZ 200336
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
836 PM MST THU NOV 19 2009
.EVENING UPDATE...
HIGH PRESSURE RIDGE WILL CONTINUE OVER THE FORECAST AREA TONIGHT.
SATELLITE SHOWING MOUNTAIN WAVE ACTIVITY UNDER THIS RIDGE ALONG
THE ENTIRE EAST SIDE OF THE ROCKY MOUNTAIN FRONT RANGE. SOME OF
THESE CLOUDS CONTINUE TO SPILL DOWN OVER OUR NORTHERN AND WESTERN
ZONES THIS EVENING. AS A RESULT...HAVE INCREASED CLOUD COVER SOME
ACROSS THESE LOCATIONS FOR THE REMAINDER OF THE NIGHT. QUIET AND
DRY WEATHER TO CONTINUE THROUGH FRIDAY.
FORECAST CONCERN FOR TONIGHT WILL BE CONTINUED WINDY CONDITIONS
ACROSS THE UPPER YELLOWSTONE AND UPPER STILLWATER VALLEYS. LEE-
SIDE TROUGHING IS IN PLACE ACROSS SOUTH CENTRAL AND SOUTHEAST
MONTANA WITH AN AREA OF LOW PRESSURE OVER SOUTHERN CANADA AND
HIGH PRESSURE OVER EASTERN IDAHO. AS A RESULT...WINDY CONDITIONS
ARE BEING OBSERVED ACROSS THE GAP AREAS OF THE WEST. PRESSURE
GRADIENTS BETWEEN LEWISTOWN AND IDAHO FALLS HAVE BEGUN TO RISE
DURING THE PAST COUPLE OF HOURS. DO NOT BELIEVE WINDS WILL REACH
ADVISORY CRITERIA TONIGHT ACROSS THESE LOCATIONS BUT IT DOES BARE
WATCHING. EVENING TEMPERATURES ARE STILL IN THE 40S FROM BILLINGS
TO LIVINGSTON DUE TO THESE DOWNSLOPE WINDS. BELIEVE READINGS WILL
COOL BUT REMAIN MILD OVERNIGHT AND HAVE RAISED OVERNIGHT LOWS
ACROSS THESE AREAS SEVERAL DEGREES AS SOME LOCATIONS MAY NOT DIP
MUCH BELOW FREEZING. OVERALL FORECAST IN GOOD SHAPE WITH UPDATE
TO ABOVE MENTIONED CHANGES OUT SHORTLY. HOOLEY
.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
ZONAL FLOW WITH LOWER HEIGHTS THAN WE HAVE SEEN OF LATE WILL
ALLOW FOR A SERIES OF PACIFIC SHORTWAVES TO AFFECT OUR AREA
THROUGH THE EXTENDED PERIOD. FIRST OF THESE WAVES WILL BE SUNDAY
AND SUNDAY NIGHT...THE SECOND MONDAY NIGHT AND TUESDAY. DOWNSLOPE
FLOW LOOKS TO BE FAIRLY STRONG WITH EACH SYSTEM SO SEE NO REASON
TO GO HIGHER THAN NEAR TO SLIGHTLY ABOVE CLIMO POPS FOR THE LOWER
ELEVATIONS. THE WESTERN SLOPES OF THE MOUNTAINS WILL BE FAVORED
FOR SOME SNOWFALL WITH EACH OF THESE...ESPECIALLY SUNDAY AND
SUNDAY NIGHT AS JET POSITION IS A BIT MORE FAVORABLE AS IT NOSES
INTO NW WYOMING. PLENTY OF INSTABILITY THROUGH THE DENDRITIC LAYER
WITH THE SUNDAY WAVE AS WELL...SO ALTHOUGH IT IS A RELATIVELY FAST
MOVING WAVE WE COULD SEE A DECENT SNOWFALL OVER OUR WESTERN
SLOPES. HAVE RAISED POPS/SNOWFALL TO ACCOUNT FOR THIS. JET ENERGY
IS A BIT FURTHER NORTH TUESDAY...AND AT AN INITIAL GLANCE THIS
COULD BE A MORE SIGNIFICANT WIND MAKER FOR THE PLAINS. WILL NEED
TO KEEP WATCH OF THIS. FOR NOW HAVE INCREASED WINDS AND ADDED A
SLIGHT POP FOR THE EASTERN PLAINS MONDAY NIGHT INTO TUESDAY NIGHT.
THOUGH IT WILL BE A QUICK HITTER PCPN-WISE...SOME TIMING
DIFFERENCES AMONG THE MEDIUM RANGE MODELS NEED TO BE WORKED OUT
YET.
WITH THE LOW HEIGHTS TEMPS SUN-TUE WILL STAY ON THE COOL SIDE
COMPARED TO THE RECENT WARMTH BUT STILL NEAR NORMAL...AGAIN PER
THE DOMINANT DOWNSLOPE REGIME EXPECTED. ZONAL FLOW DOES NOT FAVOR
ANY TAPS OF SIGNIFICANTLY COLD AIR IN NORTHERN CANADA.
MODELS STILL IN GOOD AGREEMENT IN DEVELOPING A RIDGE OVER THE
REGION WED-THU OF NEXT WEEK...AS UPPER TROF DEEPENS OVER THE
CENTRAL CONUS...SETTING UP A GOOD PERIOD OF TRAVEL CONDITIONS AND
A POTENTIALLY WARM THANKSGIVING IN OUR AREA. ENSEMBLES ALSO
SUPPORT THIS SCENARIO. WILL KEEP THE REGION DRY WITH WARMING
TEMPERATURES FOR DAYS 6 AND 7.
JKL
&&
.AVIATION...
VFR CONDITIONS ACROSS THE CWA TONIGHT AND TOMORROW. A DIGGING
TROUGH UPSTREAM OVER THE WASHINGTON COAST IS SPILLING MOISTURE
OVER THE UPPER LEVEL RIDGE AND OUR CWA CAUSING SCATTERED TO BROKEN
HIGH CLOUDS. THE HIGH CLOUDS WILL REMAIN AS THE TROUGH
APPROACHES...BUT DOWN-SLOPE CONDITIONS FROM THE SOUTHWEST FLOW WILL
PREVENT ANY LOW CLOUDS. LEE-SIDE TROUGHING AND DOWN-SLOPE FLOW WILL
CONTINUE TO CAUSE WINDY CONDITIONS EAST OF THE MOUNTAINS AND WILL
MAINLY IMPACT KLVM WITH WIND GUSTS AROUND 30 KNOTS TONIGHT. LEACH/HOOLEY
&&
.PRELIMINARY POINT TEMP/POPS...
FRI SAT SUN MON TUE WED THU
-----------------------------------------------------------
BIL 032/060 030/046 023/042 023/044 027/046 026/048 029/048
00/U 23/O 12/J 21/B 11/N 10/B 00/B
LVM 033/056 029/041 021/039 018/040 025/042 025/047 027/049
00/N 34/O 23/J 21/B 11/N 10/B 00/N
HDN 025/061 028/051 023/046 022/046 022/047 023/049 023/049
00/U 13/O 12/W 21/B 12/S 20/B 00/B
MLS 024/059 026/050 023/048 022/046 021/047 022/048 023/049
00/U 02/O 21/B 21/B 22/S 20/B 00/B
4BQ 024/058 027/051 022/045 021/043 021/043 021/046 022/046
00/U 02/O 21/B 22/J 12/S 21/B 00/B
BHK 025/058 026/054 023/046 021/043 019/043 020/043 020/045
00/U 02/R 21/B 22/J 22/S 21/B 00/B
SHR 023/059 029/047 018/043 018/042 017/044 019/045 019/047
00/B 14/O 22/W 21/B 12/S 20/B 00/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
000
FXUS65 KMSO 200325
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
825 PM MST THU NOV 19 2009
.UPDATE...
OVERNIGHT TEMPERATURES TRENDED LOWER FOR PORTIONS OF WESTERN
MONTANA AND NORTH CENTRAL IDAHO.
&&
.DISCUSSION...
WARM AIR ALOFT HAS BEGUN TO INFILTRATE THE NORTHERN
ROCKIES...HOWEVER SOME LOCATIONS HAVE NOT QUITE REACHED THEIR
MINIMUM TEMPERATURE FOR TONIGHT. BASED ON CLOUD COVERAGE AND WEAK
MIXING WITHIN SOME AREA VALLEYS...OVERNIGHT TEMPERATURES HAVE BEEN
DECREASED...PARTICULARLY IN THE MISSOULA...BITTERROOT...FLATHEAD...
AND MISSION VALLEYS. DESPITE OCCASIONAL CLOUDINESS...VALLEY
INVERSION ARE IMMINENT FOR THE CURRENT WEATHER SCENARIO.
&&
.AVIATION...
MOISTURE WILL CONTINUE TO MOVE ACROSS NORTHWEST MONTANA THIS EVENING
RESULTING IN MOUNTAIN OBSCURATIONS AND LOCAL LOWER VISIBILITIES IN
THE VALLEYS AS WELL. CLOUDS WILL GRADUALLY DECREASE ACROSS MUCH OF
THE NORTHERN ROCKIES LATER TONIGHT AS SOUTHWESTERLY FLOW ALOFT
BRINGS DRIER AIR TO THE REGION. VISIBILITY MAY BECOME BRIEFLY
REDUCED BY HAZE/SMOKE AT KSMN AROUND DAWN 19/1400Z FRIDAY MORNING.
&&
.PREV DISCUSSION... /ISSUED 241 PM MST THU NOV 19 2009/
..ABOVE NORMAL TEMPERATURES FRIDAY...QUICKLY REPLACED BY WINTRY
CONDITIONS SATURDAY AND SUNDAY...
DISCUSSION...A DEEPENING TROUGH OFF THE PACIFIC COAST WILL AMPLIFY
SOUTHWESTERLY FLOW ALOFT OVER THE INLAND WESTERN STATES. THIS
WILL DRAW DRIER AND WARMER AIR ALOFT OVER THE REGION WHICH SHOULD
PRODUCE A GRADUAL DECREASE IN CLOUD COVER OVERNIGHT. TEMPERATURES
WILL THUS BE TRICKY SINCE GOOD RADIATIONAL COOLING MIGHT BE OFF
SET SOMEWHAT BY WARMING TEMPERATURES ABOVE THE MOUNTAIN TOPS.
THE AFOREMENTIONED UPPER TROUGH WILL MOVE INLAND FRIDAY AND BRING
WIDESPREAD PRECIPITATION IN THE FORM OF VALLEY RAIN AND MOUNTAIN
SNOW IN THE EVENING...CHANGING OVER TO ALL SNOW BY SATURDAY
MORNING. THE MODELS HAVE BACKED OFF ON THEIR PREVIOUS SOLUTIONS OF SPLITTING
THE ENERGY WITH MORE ENERGY MOVING INTO NORTHERN CALIFORNIA. NOW
THE MODELS ARE KEEPING THE TROUGH MORE CONSOLIDATED AND BRING
MORE MOISTURE AND ENERGY INTO THE INTERMOUNTAIN REGION. THIS HAS
RESULTED IN CHANGES TO THE GOING FORECAST BY INCREASING
ACCUMULATIONS IN THE HIGHER VALLEYS OF NORTHERN CLEARWATER
MOUNTAINS AND INCREASING CHANCES OF PRECIPITATION IN SOUTHWEST
MONTANA AND LEMHI COUNTY FOR SATURDAY.
AN ASSOCIATED SURFACE COLD FRONT SWEEPS ACROSS THE REGION FRIDAY
NIGHT LOWERING SNOW LEVELS TO MOST VALLEY FLOORS BY EARLY SATURDAY
MORNING. BEST ACCUMULATING SNOWS LOOK TO IMPACT THE HIGHER
VALLEYS OF THE NORTHERN CLEARWATER MOUNTAINS IN NORTH CENTRAL
IDAHO...AS WELL AS THE PASSES ALONG THE MONTANA/IDAHO BORDER AND
MCDONALD...ROGERS AND HOMESTAKE PASSES ALONG THE CONTINENTAL
DIVIDE. IN ADDITION THE COLD FRONT WILL ALLOW BREEZY SOUTHWEST TO
WEST WINDS TO COMBINE WITH THE SNOW AND CREATE REDUCTIONS TO
VISIBILITIES FROM BLOWING AND DRIFTING SNOW. THE LOWER VALLEYS OF
WESTERN MONTANA...ESPECIALLY CENTRAL AND SOUTHERN VALLEYS COULD
SEE UP TO AN INCH OF WET SLUSHY SNOW BY SATURDAY MORNING. THIS
SNOW COMBINED WITH INCREASED SNOW OVER THE PASSES MAY RESULT IN
TRAVEL IMPACTS SATURDAY MORNING. AT THIS TIME...THE ACCUMULATIONS
IN THE ABOVE MENTIONED REGIONS LOOK BELOW ANY HEADLINE
CRITERIA...BUT WILL CONTINUE TO MONITOR THIS SYSTEM AS IT MOVES
ONSHORE. STAY TUNED TO LATTER FORECASTS AS WINTER HEADLINES MAY BE
NECESSARY.
SUNDAY THROUGH WEDNESDAY. THE RECENT TREND OF THE MODELS HAS BEEN
TO CONSOLIDATE THE FLOW WITH THE SUNDAY SYSTEM. IF THIS
OCCURS...IT WILL TRANSLATE INTO MORE SIGNIFICANT PRECIPITATION.
HOWEVER...GIVEN MANY RECENT SYSTEMS HAVE SPLIT SOMEWHAT...AND
IT DOES SEEM THERE IS A RESIDUAL RIDGE OF HIGH PRESSURE ALONG THE
WEST COAST...IT STILL SEEMS POSSIBLE THAT THE SUNDAY SYSTEM MAY
SPLIT AND WEAKEN A LITTLE AS IT SHIFTS ACROSS THE NORTHERN
ROCKIES. AS SUCH...WE SHOULD STILL SEE SIGNIFICANT SNOWS IN THE
MOUNTAINS AND SOME LIGHT SNOW IN THE VALLEYS...BUT MAYBE NOT
WARNING AMOUNTS FOR THE CLEARWATERS AS SOME MODELS SUGGEST. WEAK
HIGH PRESSURE SHOULD RETURN MONDAY. ANOTHER WEATHER SYSTEM MAY
BRUSH THE AREA LATE MONDAY INTO TUESDAY. THERE IS A LOT
UNCERTAINTY FOR THE THANKSGIVING TRAVEL PERIOD WITH A POSSIBLE
RIDGE OF HIGH PRESSURE AGAIN RETURNING TO THE REGION.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
UPDATE...ZUMPFE
SHORT TERM...DICKERSON/MEAD
LONG TERM....BAUCK
AVIATION...DICKERSON
000
FXUS65 KTFX 192340
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
440 PM MST THU NOV 19 2009
...UPDATE TO AVIATION...
.DISCUSSION...
TODAY THROUGH SATURDAY EVENING...HIGH PRESSURE RIDGE STILL
IN PLACE OVER THE GREAT BASIN AND EXTENDING INTO THE NORTHERN
ROCKIES. DRY AIR UNDER THE RIDGE IS PRODUCING WIDESPREAD CLEAR
SKIES AND WARM TEMPERATURES OVER MOST OF SOUTHWEST AND CENTRAL MT
THIS AFTN. ONLY EXCEPTION IS FROM GREAT FALLS NORTHWARD TO US/CAN
BORDER WHERE CHINOOK ARCH CLOUD COVER HAS REDEVELOPED IN MOIST
SOUTHWEST FLOW ALOFT ON BACKSIDE OF THE RIDGE. OTHER THAN A SLIGHT
CHANCE FOR A STRAY SNOWSHOWER ALONG THE NORTHERN ROCKY MTN
FRONT...NO PRECIPITATION IS EXPECTED ACROSS THE REGION THIS AFTN OR
TONIGHT. SHORT-TERM MODELS SHOWING GOOD AGREEMENT AND CONSISTENCY
IN BUILDING THE RIDGE OVER MT TOMORROW IN RESPONSE TO CURRENT GULF
OF ALASKA LOW PRESSURE SYSTEM DIGGING SOUTHWARD ALONG BC/WA COAST.
LOOKS LIKE MOISTURE FROM THE PACIFIC SYSTEM WILL STAY WEST OF THE
DIVIDE UNTIL FRI NIGHT. STRENGTHENING SOUTHWEST FLOW AND SCATTERED
CLOUDS WILL PROVIDE ONE MORE DAY OF WELL-ABOVE NORMAL TEMPS TOMORROW
BEFORE SURFACE COLD FRONT ASSOCIATED WITH THE PACIFIC TROF MOVES THROUGH
CENTRAL AND SOUTHWEST MT ON SATURDAY MORNING...SHARPLY DROPPING
TEMPS ON SAT BACK TO LOW-MID 40S WHICH ARE MORE TYPICAL FOR
MID-NOVEMBER. PRECIP BECOMES WIDESPREAD ACROSS SOUTHWEST MT AND
THE ROCKY MTN FRONT SAT MORNING AND AFTN...BUT PRECIP WILL TAPER OFF
AS THE UPPER TROF MAKES STEADY PROGRESS INTO EASTERN MT BY SAT EVE.
WINDS WILL REMAIN GUSTY ACROSS WESTERN PORTIONS OF THE HILINE DOWN
TO AROUND GREAT FALLS BOTH TOMORROW AND SATURDAY AS GRADIENT BETWEEN
THE RIDGE AND APPROACHING TROF CONTINUES TO BE TIGHT THROUGH THE
PERIOD. WARANAUSKAS
SATURDAY NIGHT THROUGH TUESDAY NIGHT...MEDIUM RANGE MODELS BEGINNING
TO SHOW DIFFERENCES IN THEIR RESPECTIVE SOLUTIONS. THE GFS APPEARS
TO BE FASTER IN ITS OVERALL DEPICTIONS. THE PERIOD STARTS WITH AN
UPPER TROF EXITING THE AREA TO THE EAST AS ANOTHER UPPER TROF SWINGS
ACROSS THE PACIFIC NORTHWEST. SHOWERS OVER THE WESTERN AND SOUTHWEST
MOUNTAINS WILL DEVELOP SATURDAY NIGHT. BY SUNDAY THE UPPER TROF
CROSSES THE CONTINENTAL DIVIDE AND SCATTERED SHOWERS WILL BECOME A
BIT MORE WIDESPREAD. A POSITIVE TILT UPPER RIDGE NOSES INTO WESTERN
MONTANA MONDAY BRINGING DRIER AND A LITTLE WARMER CONDITIONS TO THE
AREA. DIFFERENCE IN MODEL SOLUTIONS SHOW UP TUESDAY AS THE EUROPEAN
MODEL IS SLOWER IN BRINGING SHORT WAVE ENERGY ACROSS THE AREA. BUT
BOTH MODELS AGREE ON A STRONGER UPPER RIDGE BUILDING OVER THE
WESTERN STATES OVERNIGHT TUESDAY. TEMPERATURES WILL CONTINUE ABOVE
SEASONAL AVERAGES.
WEDNESDAY AND THURSDAY...MODELS SHOW AN UPPER LEVEL RIDGE OVER THE
REGION ON WEDNESDAY AND THURSDAY. HOWEVER...THE RIDGE DOES FLATTEN A
BIT ON THURSDAY...IN ADVANCE OF AN UPPER LEVEL WEATHER DISTURBANCE
MOVING INTO THE PACIFIC NORTHWEST...AS PER GFS MODEL.
GFS AND ECMWF BOTH SHOW GUSTY DOWN SLOPE WINDS ON WEDNESDAY.
THE PRESSURE GRADIENT WEAKENS ON THURSDAY FOR LIGHTER WINDS...WHILE
THE ECMWF SHOW A WEAK SURFACE HIGH MOVING INTO NORTHERN MONTANA
FROM BRITISH COLUMBIA. THUS...WILL GO WITH ABOVE SEASONAL AVERAGE
TEMPERATURES BOTH DAYS...ESPECIALLY WEDNESDAY AND MOSTLY DRY
CONDITIONS OVER THE PLAINS AND VALLEYS WITH A ISOLATED/SCATTERED
SNOW SHOWERS OVER THE SOUTHWEST MOUNTAINS AND ALONG THE DIVIDE.
WILLIAMSON DC
&&
.AVIATION...
UPDATED 2340Z.
SOUTHWEST FLOW ALOFT WILL CONTINUE OVER THE REGION TONIGHT THROUGH
FRIDAY AFTERNOON. MID AND HIGH LEVEL CLOUDS WILL STREAM ACROSS THE
FORECAST AREA THIS EVENING BUT EXPECT ONLY A SLIGHT CHANCE OF SNOW
SHOWERS IN THE GLACIER PARK AREA WITH DRY CONDITIONS PREVAILING
ELSEWHERE. GUSTY SOUTH TO SOUTHWEST WINDS ACROSS NORTH CENTRAL
MONTANA WILL DIMINISH BY 02Z BUT ARE EXPECTED TO INCREASE AGAIN BY
18Z FRIDAY. MPJ
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 32 57 30 42 / 0 0 20 20
CTB 32 58 33 40 / 0 0 20 20
HLN 25 51 26 41 / 0 0 40 50
BZN 16 54 24 36 / 0 0 40 50
WEY 3 42 22 30 / 0 0 50 90
DLN 19 45 25 31 / 0 0 60 50
HVR 25 62 29 48 / 0 0 10 10
LWT 26 55 29 41 / 0 0 10 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...WARANAUSKAS
LONG TERM...EMANUEL/WILLIAMSON DC
AVIATION...MPJ
WEATHER.GOV/GREATFALLS
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