000
FXUS65 KCYS 082201
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
301 PM MST SUN NOV 8 2009

.SHORT TERM...TONIGHT THROUGH TUESDAY...BREEZY WEST TO NORTHWEST
WINDS WILL CONTINUE OVER THE CWA THROUGH THE EARLY EVENING AS HIGH
PRESSURE AT THE SFC SLIDES OVER THE REGION...AND THEN SHIFTS TO THE
EAST. WINDS WILL VEER TO BECOME SOUTHEAST OVERNIGHT WHICH WILL
ENHANCE UPSLOPE LIFT IN THE SOUTHERN AREAS. COULD SEE SOME PATCHY
FOG NEAR THE SUMMIT IN THIS UPSLOPE FLOW LATE TONIGHT. A WEAK PIECE
OF UPPER LEVEL ENERGY WILL MOVE ACROSS THE REGION OVERNIGHT AND WILL
INCREASE BROAD SCALE LIFT OVER THE ROCKIES. COUPLED WITH LOW LEVEL
UPSLOPE FLOW IN PLACE...WILL SEE INCREASED CHANCES FOR PRECIPITATION
THROUGH THE MORNING. SATELLITE IMAGERY FROM THIS AFTERNOON SHOWS A
VERY DRY ATMOSPHERE WHICH SHOULD LIMIT ANY PRECIP UNTIL THE
OVERNIGHT PERIOD SO HAVE BACKED OFF ON POPS UNTIL AFTER MIDNIGHT
WHEN UPSLOPE FLOW INTENSIFIES AND LOW LEVEL MOISTURE ADVECTION
INCREASES. HOWEVER...MOISTURE STILL LOOKS ON THE LOW END SO ANY
ACCUMULATIONS WILL BE LIGHT. EXPECT LIGHT SNOW IN THE MOUNTAINS WITH
A CHANGEOVER TO RAIN OR RAIN/SNOW MIX FURTHER EAST IN THE SOUTHERN
NEBRASKA PANHANDLE. SLIGHT RIDGING ALOFT WILL OCCUR MONDAY SO WILL
SEE DRY CONDITIONS WITH TEMPS IN THE LOW TO MID 50S ACROSS THE AREA.
THIS TREND WILL CONTINUE THROUGH TUESDAY. THE LEESIDE SFC PRESSURE
TROUGH WILL RETURN ON TUESDAY WHICH WILL TIGHTEN THE SFC PRESSURE
GRADIENT ACROSS THE MOUNTAINS AND INCREASE SOUTHERLY WINDS. WILL BE
WARMER ON TUESDAY WITH TEMPS RANGING FROM THE MID 50S TO MID 60S AS
THICKNESSES STEADILY INCREASE THROUGH THE DAY.

.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...CONFIDENCE REMAINS
HIGH THROUGH MID-WEEK...BUT DROPS OFF QUICKLY FOR FRIDAY INTO THE
UPCOMING WEEKEND AS MEDIUM RANGE MODELS CONTINUE STRUGGLE WITH
PATTERN EVOLUTION. DIGGING ERN PACIFIC TROUGH WILL YIELD
RELATIVELY DRY AND WARM SOUTHWEST FLOW TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT. MOISTURE WILL BEGIN TO INCREASE INTO THE
SNOWY/SIERRA MADRES WEDNESDAY NIGHT AND MORESO DURING THE DAY ON
THURSDAY. MODELS BEGIN TO DIVERGE BY EARLY FRIDAY...AS THE 12Z GFS
SLOWS THE PATTERN PROGRESSION BY BEGINNING TO CUT OFF THE UPPER
LOW OVER THE GREAT BASIN. MEANWHILE...THE 12Z ECMWF MAINTAINS A
PROGRESSIVE SOLUTION SWEEPING THE TROUGH THROUGH THE INTERMOUNTAIN
WEST...IN A SPLIT FLOW REGIME...WHICH WAS ALSO SUPPORTED BY THE
00Z GEM. WOULD TEND TO SIDE WITH THE PROGRESSIVE SPLIT FLOW
SOLUTION...WITH THE SLOWER CUT-OFF SOLUTION ONLY SUPPORTED BY THE
06Z AND 12Z GFS. GIVEN MASSIVE UNCERTAINTIES FOR THE FRIDAY
THROUGH SUNDAY TIMEFRAME...HAVE MAINTAINED GENERALLY BROAD
PRECIPITATION CHANCES AT OR SLIGHTLY ABOVE CLIMATOLOGY UNTIL
BETTER TEMPORAL AND SPATIAL DETAILS EMERGE. LIKEWISE...TEMPERATURES
WILL COOL GIVEN THE ANTICIPATED UNSETTLED WEATHER FOR FRIDAY
THROUGH SUNDAY.

&&

.AVIATION...GENERALLY DRY WEST/SOUTHWEST FLOW WILL PERSIST AT AREA
TERMINALS OVERNIGHT. THE EXCEPTION WILL BE AT KCYS...WHERE WINDS
WILL GRADUALLY TURN SOUTHERLY THROUGH THE EVENING...INCREASING LOW
LEVEL MOISTURE ACROSS THE SOUTHERN LARAMIE RANGE AND ADJACENT
CHEYENNE FOOTHILLS. A FEW SHOWERS MAY SQUEEZE OUT OF THIS
PATTERN...BUT AT LEAST SOME MVFR CIGS ARE EXPECTED AT KCYS.
MOUNTAIN OBSCURATIONS WILL ALSO BE A CONCERN...PARTICULARLY IN THE
SOUTHERN LARAMIE RANGE. OTHERWISE VFR CONDITIONS WILL PREVAIL
THROUGH THE PERIOD.

&&

.FIRE WEATHER...BREEZY NORTHWEST WINDS WILL DECREASE THROUGH THE
EVENING AS HIGH PRESSURE MOVES INTO THE AREA. WILL SEE LIGHT
PRECIPITATION INCREASE IN COVERAGE OVERNIGHT OVER SOUTHEASTERN
PORTIONS OF THE CWA AS AN UPPER LEVEL WAVE MOVES ACROSS THE REGION
AND SURFACE FLOW SHIFTS TO THE SOUTHEAST IN THIS AREA. SNOW CAN BE
EXPECTED IN THE MOUNTAINS WITH MAINLY RAIN OR A RAIN/SNOW MIX IN
THE LOWER ELEVATIONS OF WYOMING AND THE NEBRASKA PANHANDLE.
OVERALL ACCUMULATIONS OF PRECIPITATION WILL BE LIGHT THROUGH THE
MORNING. OTHERWISE...DRY CONDITIONS WITH SEASONABLE TEMPERATURES
CAN BE EXPECTED FOR MONDAY. TUESDAY WILL BE A REPEAT OF
MONDAY...EXCEPT FOR SOUTHERLY WINDS THAT WILL BECOME BREEZY BY THE
AFTERNOON.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.

&&

$$

SHORT TERM/AVIATION...RJM
LONG TERM...HAHN

000
FXUS63 KUNR 082054
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
154 PM MST SUN NOV 8 2009

.DISCUSSION...CURRENT SURFACE MAP PLACES TROF INTO EASTERN
DAKOTAS...WITH GUSTY NORTHWEST WINDS ACROSS WESTERN SOUTH DAKOTA.
HIGH PRESSURE BUILDS IN TONIGHT WITH MOSTLY CLEAR SKIES AND LIGHT
WINDS. HIGH MOVES EAST MONDAY WITH RETURN FLOW. TEMPERATURES NEAR
GUIDANCE. UPPER RIDGE ACROSS THE AREA MONDAY NIGHT/TUESDAY.
COMBINATION OF LOW LEVEL JET AND WAA WILL RESULT IN MILD LOWS
MONDAY NIGHT. HIGHS TUESDAY AROUND 15F ABOVE AVERAGE.

EXTENDED...MAINLY DRY AND MILD WEATHER IS EXPECTED INTO THE MIDDLE
PART OF THE WEEK AS AN UPPER LEVEL RIDGE PASSES OVER THE AREA. TEMPS
WILL BE ABOVE SEASONAL AVERAGES. NEXT CHANCE FOR PRECIPITATION LOOKS
TO BE LATE THURSDAY INTO FRIDAY AS AN UPPER LEVEL TROF DIGS ACROSS
THE NORTHERN ROCKIES. SOME TIMING AND TRACK ISSUES REMAIN BETWEEN
THE MEDIUM RANGE MODELS...BUT IT LOOKS LIKE BETTER CHANCES COULD BE
THURSDAY NIGHT INTO FRIDAY. TEMPERATURES WILL COOL TO NEAR AVERAGE
LATE IN THE WEEK.

&&

.AVIATION...VFR CONDITIONS CAN BE EXPECTED THROUGH THE FORECAST
PERIOD.

&&


.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

000
FXUS65 KRIW 082052
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
152 PM MST SUN NOV 8 2009

.SHORT TERM...TONIGHT THROUGH WEDNESDAY
WEST FLOW ALOFT WILL CONTINUE WITH LIMITED MOISTURE INTO THE
NORTHWEST MOUNTAINS FOR SOME CLOUDS AND FLURRIES THIS EVENING.
OTHERWISE THE AREA WILL REMAIN DRY WITH BREEZY AREAS IN AND NEAR
THE EAST SLOPES OF THE MOUNTAINS. TEMPERATURES WILL REMAIN COOL.
LITTLE CHANGE IS EXPECTED THROUGH MONDAY AND MONDAY NIGHT. THE
FLOW ALOFT WILL BACK TO THE SOUTHEAST TUESDAY THROUGH WEDNESDAY
WITH INCREASING WINDS. THIS WILL BRING LOCAL WINDY AREAS TO THE
SOUTH AND ALONG THE EAST SLOPES OF THE MOUNTAINS. TEMPERATURES
WILL WARM SLIGHTLY WITH INCREASED DOWNSLOPE WIND AND SLIGHT WARM
AIR ADVECTION AHEAD OF A DEEPENING PACIFIC TROUGH THAT WILL MOVE
INTO THE WEST COAST ON WEDNESDAY. CLOUDS WILL INCREASE IN THE FAR
WEST. MODELS IN FAIR AGREEMENT IN THE SHORT TERM WITH A BENIGN
FORECAST BRINGING ABOVE AVERAGE CONFIDENCE IN THE FORECAST.

.LONG TERM...THURSDAY THROUGH SUNDAY

A FAIRLY ACTIVE EXTENDED IS EXPECTED WITH A SPLITTING TROUGH
AFFECTING THE AREA PRIMARILY WEDNESDAY NIGHT THROUGH FRIDAY.
HOWEVER...THIS FAR OUT MEDIUM RANGE MODELS HAVE SIGNIFICANT
TIMING...STRENGTH AND POSITION OF THIS SPLITTING TROUGH. ON
WEDNESDAY...SOUTHWEST FLOW AHEAD OF THE TROUGH AXIS COULD PRODUCE
SOME PRECIPITATION OUT WEST AND DRY WITH ABOVE AVERAGE TEMPERATURES
EAST OF THE DIVIDE. THE 00Z ECMWF IS A BIT STRONGER THAN THE 00Z GFS
WITH MORE OF AN IMPACT ACROSS THE AREA THURSDAY/FRIDAY.  THE GFS
ENSEMBLES SUPPORT A SLOWER MOVEMENT OF THIS TROUGH THAN THE
OPERATIONAL 00Z RUN. HAVE HIGHEST POPS WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT OUT WEST FOR THIS SYSTEM.  MEDIUM RANGE MODELS ARE
CONSISTENT IN NOT BRINGING UPSLOPE CONDITIONS EAST OF THE DIVIDE AS
FLOW STAYS WEST TO NORTHWEST EVEN BEHIND THE TROUGH...WITH LITTLE
HINT OF NORTHERLY WINDS AT THIS TIME.  BEHIND THIS TROUGH...LOOKS
LIKE A DRY PERIOD EITHER FRIDAY OR FRIDAY NIGHT.  THE ECMWF BRINGS
IN ANOTHER TROUGH INTO THE AREA ON SATURDAY...WHILE THE GFS HAS A
STRONG WESTERLY FLOW.  HAVE GONE WITH CLIMO POPS FOR SATURDAY AND
SUNDAY...WITH AN EMPHASIS OVER THE WEST.  ABOVE AVERAGE TEMPERATURES
ARE EXPECTED ON WEDNESDAY...WITH A COOLING TREND BACK TO SEASONAL TO
SLIGHTLY BELOW AVERAGE FRIDAY THROUGH SUNDAY.

&&

.AVIATION...
VFR CONDITIONS WITH SUSTAINED WIND SPEEDS LESS THAN 10KTS WILL
PREVAIL OVER WESTERN AND CENTRAL WYOMING THIS EVENING THROUGH SUNDAY
MORNING. LCL MVFR CEILINGS ARE POSSIBLE OVER THE NORTHWEST MOUNTAINS
THROUGH APPROXIMATELY 03Z MONDAY.

&&

.FIRE WEATHER...
WEST FLOW WILL CONTINUE OVER WYOMING WITH LIMITED MOISTURE. SOME
CLOUDS AND FLURRIES WILL BE SEEN IN THE NORTHWEST MOUNTAINS OTHERWISE
DRY AND BREEZY CONDITIONS WILL CONTINUE TONIGHT AND MONDAY.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...C.BAKER
LONG TERM...WM
AVIATION...CHURCH
FIRE WEATHER...CHURCH

000
FXUS65 KCYS 081842
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1142 AM MST SUN NOV 8 2009

.UPDATE...REDUCED SKY COVER AND POPS FOR TODAY BASED ON CURRENT
VISIBLE SATELLITE IMAGERY TRENDS. SOME HIGH CLOUDS ARE MOVING
ACROSS THE REGION EAST OF A LINE CHEYENNE TO CHADRON WITH CUMULUS
BUILDING OVER THE MOUNTAIN TOPS ACROSS CARBON COUNTY. KEPT THESE
AREAS PARTLY TO MOSTLY CLOUDY WITH THE REMAINING LOCATIONS MOSTLY
SUNNY. ALSO KEPT A SLIGHT CHANCE FOR SHOWERS OVER THE MOUNTAIN
TOPS OF THE SIERRA MADRE AND SNOWY RANGES OTHERWISE REDUCED ALL
POPS THROUGH THE EARLY EVENING AS WATER VAPOR IMAGERY SHOWS DRIER
AIR MOVING ACROSS UTAH AND WYOMING.

.PREV DISCUSSION... /ISSUED 240 AM MST SUN NOV 8 2009/

SHORT TERM...TODAY THROUGH MONDAY NIGHT...
LATEST IR IMAGERY SHOWING A BAND OF CLOUDS EXTENDING FROM CRAIG
COLORADO NORTHWARD THROUGH RAWLINS AND TOWARDS THE NORTHERN
LARAMIE RANGE. RADAR REFLECTIVITY INDICATES 10 TO 20 DBZ RETURNS
WITH RAWLINS REPORTING LIGHT RAIN AT 1 AM MST. HAVE UPDATED THE
FORECAST TO INCLUDE A SLIGHT CHANCE OF RAIN AND MIXED RAIN AND
SNOW TO CONTINUE THROUGH THE EARLY MORNING HOURS. THE 06Z NAM
SHOWS THIS PRECIPITATION SHIFTING NORTHEAST ACROSS THE NORTHERN
ZONES BY 12Z THIS MORNING. THUS HAVE KEPT A SLIGHT CHANCE
MENTIONED THROUGH MID MORNING.

BETWEEN NOW AND 12Z THIS MORNING BOTH THE NAM AND GFS INDICATE THE
PRESSURE GRADIENT TIGHTENING WITH THE SURFACE LOW OVER EASTERN
COLORADO SLOWLY MOVING EAST AND THE HIGH PRESSURE ACROSS WESTERN
WYOMING. THIS WILL ALLOW NORTHWEST WINDS TO INCREASE ACROSS
SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE WITH A POTENTIAL FOR
WIND GUSTS UP TO 35 MPH IN WYOMING. HOWEVER...DO NOT ANTICIPATE
WINDS TO REACH ANY HIGH WIND CRITERIA IN WYOMING OR WIND ADVISORY
CRITERIA IN THE NEBRASKA PANHANDLE. THE PRESSURE GRADIENT WILL
BEGIN TO RELAX THROUGH MID MORNING INTO THE AFTERNOON WITH WINDS
SLOWLY DECREASING BY LATE AFTERNOON.

AS THE SURFACE HIGH PRESSURE BEGINS TO SHIFT EAST THE SURFACE
WINDS WILL SWITCH FROM NORTHWEST TO A SOUTH AND SOUTHEASTERLY
COMPONENT SUNDAY NIGHT INTO MONDAY MORNING. THIS WILL ALLOW FOR
UPSLOPE FLOW ALONG THE COLORADO...WYOMING AND NEBRASKA BORDERS.
BOTH THE GFS AND THE ECMWF HAVE BEEN CONSISTENT IN DEVELOPING SOME
PRECIPITATION OVER THE AREA ON SUNDAY NIGHT INTO MONDAY MORNING.
NOT BUYING INTO THE NAM WHICH HAS BEEN CONSISTENTLY DRY. THUS HAVE
KEPT THE SLIGHT CHANCE OF PRECIPITATION WITH THE ANTICIPATION OF
LOW CLOUDS OR FOG DEVELOPING ALONG THE BORDER WITH POTENTIAL FOR
LIGHT PRECIPITATION OVERNIGHT. EXPECT LIGHT SNOW IN THE MOUNTAINS
WITH A MIX OF RAIN IN SNOW ACROSS THE CHEYENNE RIDGE THEN
TRANSITIONING OVER TO RAIN IN THE SOUTHERN NEBRASKA PANHANDLE.
LITTLE IF ANY ACCUMULATION OF SNOW IS ANTICIPATED IN THE
MOUNTAINS. WITH THE CLOUD COVER AND PRECIPITATION...TEMPERATURES
ACROSS THE AREA ON MONDAY WILL BE NEARLY 10F DEGREES COOLER
COMPARED TO TODAY WITH HIGHS IN THE MID 40S TO LOWER 50S. BY
LATE MONDAY THE PRECIPITATION WILL DIMINISH AS AN UPPER LEVEL
SHORTWAVE RIDGE BEGINS TO SHIFT EAST INTO THE AREA.

LONG TERM...TUESDAY THROUGH SATURDAY...
UPPER RIDGE AXIS PASSES EAST OF THE CWA EARLY TUESDAY LEAVING WSW
UPPER FLOW ACROSS THE REGION THROUGH WEDNESDAY. QUITE MILD AND
MAINLY DRY WEATHER EXPECTED THROUGH WEDS NIGHT THEN NEXT UPPER
SYSTEM SHOULD AFFECT THE CWA DURING THE LATER PART OF THE WEEK...
MAINLY LATE THURSDAY INTO FRIDAY. MODELS SIMILAR WITH HANDLING OF
THIS SYSTEM WITH GFS QUICKER WITH THE UPPER TROF...MOVING IT EAST
OF THE CWA BY LATE FRIDAY WHILE ECMWF ABOUT 12 HOURS SLOWER. FOR
NOW WILL LEAN TOWARD A SOMEWHAT SLOWER SOLUTION AS GFS TENDS TO BE
A LITTLE TOO FAST IN THIS FLOW PATTERN. PACIFIC COLD FRONT SHOULD
SWEEP ACROSS THE CWA BY LATE THURSDAY AS UPPER TROF MOVES INTO THE
NORTHERN ROCKYS AND GREAT BASIN WITH MORE SEASONAL TEMPERATURES
EXPECTED FRIDAY AND SATURDAY. SCTD RAIN AND SNOW SHOWERS SHOULD
SPREAD INTO THE FAR WESTERN CWA LATE WEDS NIGHT AND THURSDAY THEN
ACROSS MUCH OF THE REST OF THE CWA THURSDAY NIGHT AND FRIDAY.
SATURDAY CURRENTLY LOOKING MAINLY DRY AS CWA SHOULD BE IN BETWEEN
SYSTEMS THEN.

AVIATION...
LOWER CIGS ACROSS AREAS EXTENDING FROM KCAG TO KRWL TO KDGW AS THE
BAND OF LIGHT PRECIPITATION MOVES NORTHEAST ACROSS THE AREA. THIS
SHOULD BE EXPECTED THROUGH 12Z. ELSEWHERE ACROSS THE AREA EXPECT VFR
CONDITIONS. EXPECT CIGS TO TO LOWER ON SUNDAY NIGHT INTO MONDAY
MORNING WITH POTENTIAL FOR FOG AND LIGHT PRECIPITATION TO DEVELOP.

FIRE WEATHER...
NORTHWEST WINDS WILL INCREASE THIS MORNING ACROSS THE AREA AS THE
PRESSURE GRADIENT TIGHTENS ACROSS THE AREA AND CONTINUES THROUGH
THE EARLY EVENING. SOME AREAS COULD SEE GUSTS AROUND 35 MPH...WITH
STRONGEST WINDS IN EXTREME SOUTHEAST WYOMING. WITH COOLER TEMPS
BEHIND A FRONT...MINIMUM RELATIVE HUMIDITIES TODAY SHOULD REMAIN
IN THE 20S. WILL SEE PRECIPITATION INCREASE IN COVERAGE TONIGHT INTO
MONDAY MORNING AS AN UPPER LEVEL WAVE MOVES ACROSS THE REGION AND
SURFACE FLOW SHIFTS TO THE SOUTHERLY COMPONENT. SNOW CAN BE
EXPECTED IN THE MOUNTAINS WITH MAINLY RAIN OR A RAIN/SNOW MIX IN
THE LOWER ELEVATIONS OF WYOMING AND THE NEBRASKA PANHANDLE.
OVERALL ACCUMULATIONS OF PRECIPITATION WILL BE LIGHT THROUGH EARLY
MONDAY AFTERNOON.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.

&&

$$

SHORT TERM/AVIATION...MAK
LONG TERM...RE

000
FXUS63 KUNR 080948
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
248 AM MST SUN NOV 8 2009

.DISCUSSION...09Z SFC ANALYSIS SHOWED A LOW PRESSURE CENTER OVER
EASTERN COLORADO WITH A WEAK TROUGH EXTENDING NORTHWARD INTO THE
WESTERN DAKOTAS. HIGH PRESSURE WAS LOCATED OVER THE NORTHERN ROCKIES.
REGIONAL RADAR MOSAIC WAS SHOWING A FEW LIGHT RETURNS RESULTING FROM
LIFT ASSOCIATED WITH AN UPPER SHORTWAVE CROSSING THE AREA...BUT
WITH DRY AIR IN THE LOWER LEVEL EXPECT ONLY A FEW SPRINKLES WILL BE
ABLE TO REACH THE GROUND. THE SHORTWAVE WILL MOVE EAST OF THE AREA
THIS MORNING...LEADING TO DECREASING CLOUDS. AN UPPER RIDGDE
BUILDING OVER THE AREA WILL BRING MORE DRY WEATHER FOR MONDAY AND
TUESDAY. HIGH TEMPERATURES WILL BE NEAR NORMAL TODAY AND MONDAY...
WITH WARMER TEMPERATURES ON TUESDAY AS THE UPPER RIDGE AXIS CROSSES
THE REGION.

EXTENDED...MAINLY DRY AND MILD WEATHER IS EXPECTED INTO THE MIDDLE
PART OF THE WEEK AS AN UPPER LEVEL RIDGE PASSES OVER THE AREA. TEMPS
WILL BE ABOVE SEASONAL AVERAGES. NEXT CHANCE FOR PRECIPITATION LOOKS
TO BE THURSDAY INTO FRIDAY AS AN UPPER LEVEL TROF DIGS ACROSS THE
NORTHERN ROCKIES. SOME TIMING AND TRACK ISSUES REMAIN BETWEEN THE
MEDIUM RANGE MODELS...BUT IT LOOKS LIKE BETTER CHANCES COULD BE
THURSDAY NIGHT INTO FRIDAY. TEMPERATURES WILL COOL TO NEAR AVERAGE
LATE IN THE WEEK.

&&

.AVIATION...VFR CONDITIONS CAN BE EXPECTED THROUGH THE FORECAST
PERIOD. A FEW LIGHT SHOWERS ARE POSSIBLE ACROSS NORTHERN AND EASTERN
PORTIONS OF THE FORECAST AREA THIS MORNING.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

000
FXUS65 KRIW 080943
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
243 AM MST SUN NOV 8 2009

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT

A LOW AMPLITUDE SHORTWAVE IN NEARLY ZONAL FLOW AT H5 WILL MOVE
ACROSS WY THIS MORNING AND WEAKEN AS IT LIFTS NORTHEASTWARD ACROSS
THE NORTHERN PLAINS THIS AFTERNOON. A WEAK COLD FRONT ASSOCIATED
WITH THIS SHORTWAVE WILL PUSH INTO NORTHERN CO AND THE WESTERN
PLAINS THIS MORNING...AND SURFACE HIGH PRESSURE FROM THE NORTHERN
GREAT BASIN WILL BUILD ACROSS WY. CAA BEHIND THE COLD FRONT WILL
WEAKEN SIGNIFICANTLY THIS AFTERNOON ACROSS WESTERN AND CENTRAL
WY...BUT COLDER AIR MASS ALOFT WILL KEEP HIGH TEMPERATURES ACROSS THE
REGION MUCH COOLER...10 TO 15 F COOLER...THAN HIGHS ON SATURDAY.
MUCH DRIER LOW LEVEL AIR MASS FROM THE GREAT BASIN WILL PREDOMINATE
ACROSS WESTERN AND CENTRAL WY TONIGHT. DEWPOINTS ACROSS THE REGION
WILL FALL INTO THE SINGLE DIGITS AND TEENS LATE THIS AFTERNOON AND
TONIGHT. THESE LOWER DEWPOINTS IN CONJUNCTION WITH CLEAR TO MOSTLY
CLEAR SKIES AND LIGHT WINDS WILL RESULT IN COLDER LOW TEMPERATURES
TONIGHT IN THE BASINS AND VALLEYS...WHERE STRONG RADIATIONAL COOLING
IS EXPECTED. LOWS IN THE SINGLES DIGITS AND TEENS WILL OCCUR IN THE
LOWER ELEVATIONS WEST OF THE DIVIDE TONIGHT...WHILE LOWS IN THE 20S
ARE EXPECTED EAST OF THE DIVIDE. THE CENTER OF SFC HIGH PRESSURE
WILL SHIFT TO THE EAST MONDAY...AS A COMPACT...BUT
PRONOUNCED...RIDGE BUILDS AMPLIFIES ACROSS THE NORTHERN ROCKIES AND
INTERIOR WESTERN CANADA. A VERY DRY AIR MASS...WARMING TEMPERATURES
ALOFT AND NEAR MAXIMUM SUNSHINE MONDAY WILL ALLOW HIGH TEMPERATURES
TO REBOUND BY 2 TO 5 F...WHICH WILL BE 4 TO 7 F ABOVE NORMAL.
SLOW-MOVING LARGE SCALE TROUGH WILL APPROACH THE WEST COAST TUESDAY
AND TUESDAY NIGHT. PLUME OF MID LEVEL MOISTURE FROM
NORTHERN/CENTRAL CA ACROSS THE NORTHERN GREAT BASIN AND INTO WESTERN
WY. THE INCREASE IN MID LEVEL MOISTURE AND UPSLOPE WEST TO WEST
SOUTHWEST FLOW ALOFT WILL BRING SLIGHT CHANCES OF RAIN AND
HIGH-ELEVATION SNOW TO WESTERN WY TUESDAY NIGHT AND WEDNESDAY.
DOWNSLOPING FLOW AND A THERMAL RIDGE AT H7 EAST OF THE DIVIDE
TUESDAY WILL PRODUCE DRY WEATHER AND HIGH TEMPERATURES 10 TO 15 F
ABOVE NORMAL.

.LONG TERM...WEDNESDAY THROUGH SUNDAY

A FAIRLY ACTIVE EXTENDED IS EXPECTED WITH A SPLITTING TROUGH
AFFECTING THE AREA PRIMARILY WEDNESDAY NIGHT THROUGH FRIDAY.
HOWEVER...THIS FAR OUT MEDIUM RANGE MODELS HAVE SIGNIFICANT
TIMING...STRENGTH AND POSITION OF THIS SPLITTING TROUGH. ON
WEDNESDAY...SOUTHWEST FLOW AHEAD OF THE TROUGH AXIS COULD PRODUCE
SOME PRECIPITATION OUT WEST AND DRY WITH ABOVE AVERAGE TEMPERATURES
EAST OF THE DIVIDE. THE 00Z ECMWF IS A BIT STRONGER THAN THE 00Z GFS
WITH MORE OF AN IMPACT ACROSS THE AREA THURSDAY/FRIDAY.  THE GFS
ENSEMBLES SUPPORT A SLOWER MOVEMENT OF THIS TROUGH THAN THE
OPERATIONAL 00Z RUN. HAVE HIGHEST POPS WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT OUT WEST FOR THIS SYSTEM.  MEDIUM RANGE MODELS ARE
CONSISTENT IN NOT BRINGING UPSLOPE CONDITIONS EAST OF THE DIVIDE AS
FLOW STAYS WEST TO NORTHWEST EVEN BEHIND THE TROUGH...WITH LITTLE
HINT OF NORTHERLY WINDS AT THIS TIME.  BEHIND THIS TROUGH...LOOKS
LIKE A DRY PERIOD EITHER FRIDAY OR FRIDAY NIGHT.  THE ECMWF BRINGS
IN ANOTHER TROUGH INTO THE AREA ON SATURDAY...WHILE THE GFS HAS A
STRONG WESTERLY FLOW.  HAVE GONE WITH CLIMO POPS FOR SATURDAY AND
SUNDAY...WITH AN EMPHASIS OVER THE WEST.  ABOVE AVERAGE TEMPERATURES
ARE EXPECTED ON WEDNESDAY...WITH A COOLING TREND BACK TO SEASONAL TO
SLIGHTLY BELOW AVERAGE FRIDAY THROUGH SUNDAY.

&&

.AVIATION...

LINGERING SNOW SHOWERS IN THE NW MTS AND IN THE NORTHERN HALF OF THE
BIGHORN MTS UNTIL 16Z MAY PRODUCE LOCAL MVFR CONDITIONS AND MOUNTAIN
OBSCURATION. THE PRECIP WILL END BY 18Z. OTHERWISE VFR CONDITIONS
WILL OCCUR TODAY INTO THIS EVENING.

&&

.FIRE WEATHER...

A COLD FRONT WILL MOVE SOUTH OF WYOMING TODAY...AS SURFACE HIGH
PRESSURE MOVES ACROSS THE STATE FROM THE NORTHERN GREAT BASIN.
COOLER AIR MASS WILL RESULT IN HIGH TEMPERATURES 10 TO 15 F COOLER
THAN HIGHS ON SATURDAY AND MINIMUM RELATIVE HUMIDITY IN THE 20 TO 30
PERCENT RANGE IN THE LOWER ELEVATIONS. AS SURFACE HIGH PRESSURE
BUILDS ACROSS THE NORTHERN ROCKIES TODAY...WINDS WILL DECREASE AND
BECOME LIGHT DURING THE AFTERNOON HOURS. WARMER AIR MASS ALOFT AND
DRIER AIR NEAR THE SURFACE MONDAY WILL RESULT IN HIGH TEMPERATURES 4
TO 7 F ABOVE NORMAL. LIGHT WINDS ARE EXPECTED AGAIN ON MONDAY.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SHORT TERM...SMITH
LONG TERM...WM
AVIATION...AR
FIRE WEATHER...SMITH

000
FXUS65 KCYS 080940
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
240 AM MST SUN NOV 8 2009

.SHORT TERM...TODAY THROUGH MONDAY NIGHT...
LATEST IR IMAGERY SHOWING A BAND OF CLOUDS EXTENDING FROM CRAIG
COLORADO NORTHWARD THROUGH RAWLINS AND TOWARDS THE NORTHERN
LARAMIE RANGE. RADAR REFLECTIVITY INDICATES 10 TO 20 DBZ RETURNS
WITH RAWLINS REPORTING LIGHT RAIN AT 1 AM MST. HAVE UPDATED THE
FORECAST TO INCLUDE A SLIGHT CHANCE OF RAIN AND MIXED RAIN AND
SNOW TO CONTINUE THROUGH THE EARLY MORNING HOURS. THE 06Z NAM
SHOWS THIS PRECIPITATION SHIFTING NORTHEAST ACROSS THE NORTHERN
ZONES BY 12Z THIS MORNING. THUS HAVE KEPT A SLIGHT CHANCE
MENTIONED THROUGH MID MORNING.

BETWEEN NOW AND 12Z THIS MORNING BOTH THE NAM AND GFS INDICATE THE
PRESSURE GRADIENT TIGHTENING WITH THE SURFACE LOW OVER EASTERN
COLORADO SLOWLY MOVING EAST AND THE HIGH PRESSURE ACROSS WESTERN
WYOMING. THIS WILL ALLOW NORTHWEST WINDS TO INCREASE ACROSS
SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE WITH A POTENTIAL FOR
WIND GUSTS UP TO 35 MPH IN WYOMING. HOWEVER...DO NOT ANTICIPATE
WINDS TO REACH ANY HIGH WIND CRITERIA IN WYOMING OR WIND ADVISORY
CRITERIA IN THE NEBRASKA PANHANDLE. THE PRESSURE GRADIENT WILL
BEGIN TO RELAX THROUGH MID MORNING INTO THE AFTERNOON WITH WINDS
SLOWLY DECREASING BY LATE AFTERNOON.

AS THE SURFACE HIGH PRESSURE BEGINS TO SHIFT EAST THE SURFACE
WINDS WILL SWITCH FROM NORTHWEST TO A SOUTH AND SOUTHEASTERLY
COMPONENT SUNDAY NIGHT INTO MONDAY MORNING. THIS WILL ALLOW FOR
UPSLOPE FLOW ALONG THE COLORADO...WYOMING AND NEBRASKA BORDERS.
BOTH THE GFS AND THE ECMWF HAVE BEEN CONSISTENT IN DEVELOPING SOME
PRECIPITATION OVER THE AREA ON SUNDAY NIGHT INTO MONDAY MORNING.
NOT BUYING INTO THE NAM WHICH HAS BEEN CONSISTENTLY DRY. THUS HAVE
KEPT THE SLIGHT CHANCE OF PRECIPITATION WITH THE ANTICIPATION OF
LOW CLOUDS OR FOG DEVELOPING ALONG THE BORDER WITH POTENTIAL FOR
LIGHT PRECIPITATION OVERNIGHT. EXPECT LIGHT SNOW IN THE MOUNTAINS
WITH A MIX OF RAIN IN SNOW ACROSS THE CHEYENNE RIDGE THEN
TRANSITIONING OVER TO RAIN IN THE SOUTHERN NEBRASKA PANHANDLE.
LITTLE IF ANY ACCUMULATION OF SNOW IS ANTICIPATED IN THE
MOUNTAINS. WITH THE CLOUD COVER AND PRECIPITATION...TEMPERATURES
ACROSS THE AREA ON MONDAY WILL BE NEARLY 10F DEGREES COOLER
COMPARED TO TODAY WITH HIGHS IN THE MID 40S TO LOWER 50S. BY
LATE MONDAY THE PRECIPITATION WILL DIMINISH AS AN UPPER LEVEL
SHORTWAVE RIDGE BEGINS TO SHIFT EAST INTO THE AREA.

.LONG TERM...TUESDAY THROUGH SATURDAY...
UPPER RIDGE AXIS PASSES EAST OF THE CWA EARLY TUESDAY LEAVING WSW
UPPER FLOW ACROSS THE REGION THROUGH WEDNESDAY. QUITE MILD AND
MAINLY DRY WEATHER EXPECTED THROUGH WEDS NIGHT THEN NEXT UPPER
SYSTEM SHOULD AFFECT THE CWA DURING THE LATER PART OF THE WEEK...
MAINLY LATE THURSDAY INTO FRIDAY. MODELS SIMILAR WITH HANDLING OF
THIS SYSTEM WITH GFS QUICKER WITH THE UPPER TROF...MOVING IT EAST
OF THE CWA BY LATE FRIDAY WHILE ECMWF ABOUT 12 HOURS SLOWER. FOR
NOW WILL LEAN TOWARD A SOMEWHAT SLOWER SOLUTION AS GFS TENDS TO BE
A LITTLE TOO FAST IN THIS FLOW PATTERN. PACIFIC COLD FRONT SHOULD
SWEEP ACROSS THE CWA BY LATE THURSDAY AS UPPER TROF MOVES INTO THE
NORTHERN ROCKYS AND GREAT BASIN WITH MORE SEASONAL TEMPERATURES
EXPECTED FRIDAY AND SATURDAY. SCTD RAIN AND SNOW SHOWERS SHOULD
SPREAD INTO THE FAR WESTERN CWA LATE WEDS NIGHT AND THURSDAY THEN
ACROSS MUCH OF THE REST OF THE CWA THURSDAY NIGHT AND FRIDAY.
SATURDAY CURRENTLY LOOKING MAINLY DRY AS CWA SHOULD BE IN BETWEEN
SYSTEMS THEN.

&&

.AVIATION...
LOWER CIGS ACROSS AREAS EXTENDING FROM KCAG TO KRWL TO KDGW AS THE
BAND OF LIGHT PRECIPITATION MOVES NORTHEAST ACROSS THE AREA. THIS
SHOULD BE EXPECTED THROUGH 12Z. ELSEWHERE ACROSS THE AREA EXPECT VFR
CONDITIONS. EXPECT CIGS TO TO LOWER ON SUNDAY NIGHT INTO MONDAY
MORNING WITH POTENTIAL FOR FOG AND LIGHT PRECIPITATION TO DEVELOP.

&&

.FIRE WEATHER...
NORTHWEST WINDS WILL INCREASE THIS MORNING ACROSS THE AREA AS THE
PRESSURE GRADIENT TIGHTENS ACROSS THE AREA AND CONTINUES THROUGH
THE EARLY EVENING. SOME AREAS COULD SEE GUSTS AROUND 35 MPH...WITH
STRONGEST WINDS IN EXTREME SOUTHEAST WYOMING. WITH COOLER TEMPS
BEHIND A FRONT...MINIMUM RELATIVE HUMIDITIES TODAY SHOULD REMAIN
IN THE 20S. WILL SEE PRECIPITATION INCREASE IN COVERAGE TONIGHT INTO
MONDAY MORNING AS AN UPPER LEVEL WAVE MOVES ACROSS THE REGION AND
SURFACE FLOW SHIFTS TO THE SOUTHERLY COMPONENT. SNOW CAN BE
EXPECTED IN THE MOUNTAINS WITH MAINLY RAIN OR A RAIN/SNOW MIX IN
THE LOWER ELEVATIONS OF WYOMING AND THE NEBRASKA PANHANDLE.
OVERALL ACCUMULATIONS OF PRECIPITATION WILL BE LIGHT THROUGH EARLY
MONDAY AFTERNOON.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.

&&

$$

SHORT TERM/AVIATION...MAK
LONG TERM...RE

000
FXUS63 KUNR 080234
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
734 PM MST SAT NOV 7 2009

.DISCUSSION...HAVE UPDATED FCST TO ADD MENTION OF ISOLD -SHRA ACRS
SCNTRL SD THROUGH THE NIGHT. KUNR 00Z SOUNDING DOES SHOW SOME
MINIMAL INSTABILITY ABOVE 700MB...AND WITH WEAK SHORT WAVE
EMBEDDED IN SW FLOW ALOFT SOME ECHOES ARE SHOWING UP FROM THE NEB
PANHANDLE THROUGH SCNTRL SD. EVEN THOUGH AMS IS QUITE DRY...THERE
HAVE BEEN REPORTS OF SPRINKLES (AND EVEN A LIGHTNING STRIKE WEST
OF WHITE RIVER). REST OF FCST LOOKS GOOD WITH STILL A POSSIBILITY
OF A FEW -SHRA ACRS NWRN PORTIONS OF OUR CWFA AS WELL.

&&

.PREV DISCUSSION... /ISSUED 156 PM MST SAT NOV 7 2009/

DISCUSSION...CURRENT SURFACE MAP PLACES HIGH PRESSURE ACROSS
EASTERN SOUTH DAKOTA...WITH WEAK TROF ACROSS EASTERN WYOMING.
SHORTWAVE MOVING INTO THE PACIFIC NORTHWEST WILL MOVE ACROSS
NORTHERN ROCKIES TONIGHT...AND ACROSS ND ON SUNDAY. MODELS
CONTINUE TO SHOW WEAK LIFT/MARGINAL QPF ACROSS NW SD TONIGHT...SO
WILL LEAVE IN ISOLATED SHOWERS. DRY WEATHER SUNDAY AS COLD FRONT
MOVES THROUGH. WARMER ON MONDAY WITH UPPER LEVEL RIDGING.

EXTENDED...MAINLY DRY AND MILD WEATHER IS EXPECTED INTO THE MIDDLE
PART OF NEXT WEEK AS AN UPPER LEVEL RIDGE PASSES OVER THE AREA.
TEMPS WILL GENERALLY BE ABOVE SEASONAL AVERAGES. NEXT CHANCE FOR
PRECIPITATION LOOKS TO BE LATE THURSDAY INTO FRIDAY AS NEXT UPPER
TROF DIGS INTO THE NORTHERN ROCKIES. OPERATIONAL GFS DIFFERS FROM
ITS ENSEMBLE MEMBERS AND LATEST EC WITH TIMING OF THIS TROF. OP GFS
BRINGS TROF THROUGH MUCH EARLIER...WHILE OTHER SOLNS KEEP RIDGING
OVER THE NORTHERN PLAINS THROUGH WEDNESDAY. WILL SIDE WITH SLOWER
SOLN FOR THE EXTENDED. TEMPERATURES WILL COOL TO NEAR AVERAGE LATE
IN THE WEEK.

&&

AVIATION...VFR CONDITIONS CAN BE EXPECTED THROUGH THE FORECAST
PERIOD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$
JOHNSON

000
FXUS65 KRIW 072232
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
332 PM MST SAT NOV 7 2009

.SHORT TERM...TONIGHT THROUGH TUESDAY
STRONG...SOMEWHAT MOIST SOUTHWEST FLOW FROM H7 UP TO H2 CONTINUING
OVER WESTERN AND CENTRAL WYOMING TODAY. THIS STRONG DIFLUENT
FLOW AND ENOUGH PACIFIC MOISTURE IN THE FLOW COMBINING TO PRODUCE
SCATTERED SNOW SHOWERS ALONG AND WEST OF THE DIVIDE THIS
AFTERNOON. MID AND UPPER LEVEL INSTABILITY IN THIS DIFLUENT FLOW
FORECAST BY ALL NUMERICAL PREDICTION MODELS TO CONTINUE INTO THE
EARLY MORNING HOURS. INTRODUCE SCATTERED SNOW SHOWERS TO THE WIND
RIVER MOUNTAINS...MAINLY FOR THE WEST SLOPES BUT WITH ISOLATED
SHOWERS EXPECTED TO MAKE IT UP AND OVER THE MOUNTAIN CRESTS.
ANOTHER SHORT-WAVE TROUGH/VORT-LOBE WILL CLIP NORTHWEST WYOMING
TONIGHT. RAISED SNOW SHOWER CHANCES FROM APPROXIMATELY GRAND TETON
PARK NORTHWARD INTO YELLOWSTONE PARK FOR TONIGHT AS 12Z GFS
CONTINUES WITH RIGHT REAR QUAD OF 110-KT JET STREAM REMAINING OVER
THE CWA THROUGH ABOUT 09Z SUNDAY. A GOOD DEAL OF MID-LEVEL DRY AIR
FROM THE CENTRAL GREAT BASIN WILL MAKE WIDESPREAD SNOWFALL
UNLIKELY WITH PLENTY OF DRY AIR ENTRAINMENT OCCURRING IN DEVELOPING
CUMULUS. THE SHORT-WAVE TROUGH AND ASSOCIATED JET STREAK RACE
NORTHEAST OF THE AREA EARLY SUNDAY MORNING. THE SOUTHWESTERLY FLOW
ALOFT FLATTENS ON SUNDAY WITH CAA TAKING PLACE. NEXT DISCERNIBLE
SHORT-WAVE TROUGH PROGGED TO MOVE THROUGH SOUTHERN WYOMING MONDAY
MORNING. ENOUGH ATMOSPHERIC LIFT AND PACIFIC MOISTURE ARE
EXPECTED FOR AT LEAST A MENTION OF A SLIGHT CHANCE OF SHOWERS FOR
CENTRAL AND EASTERN SWEETWATER COUNTY. A SHORT-WAVE RIDGE IS
EXPECTED TO TRANSLATE EASTWARD OVER WESTERN AND CENTRAL WYOMING
LATE-DAY MONDAY AND MONDAY NIGHT. THE FLOW ALOFT IS EXPECTED TO
BACK TUESDAY WITH A STRONG SOUTHWEST FLOW ALOFT DEVELOPING...SIMILAR TO
TODAY..

.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
PACIFIC MOISTURE REMAINS TO THE WEST UNTIL WEDNESDAY AS THE
PACIFIC TROUGH MOVES INLAND. PRECIPITATION... MAINLY SNOW WITH
SOME RAIN IN THE VALLEYS WILL MOVE INTO THE WEST, WINDS WILL PICK
UP EAST OF THE DIVIDE. THURSDAY THE TROUGH WILL PASS TROUGH THEN
FOLLOWED BY A CANADIAN TROUGH. THIS WILL SPREAD THE THREAT OF
PRECIPITATION EAST OF THE DIVIDE. MODELS HAVE BEEN INCONSISTENT
WITH THE STRENGTH OF THE CLIPPER TROUGH AND THE AMOUNT OF
PRECIPITATION WITH IT. FORECAST RATHER CONSERVATIVE AT THIS TIME
DUE TO MODEL FLIP FLOPS. SHOULD BE COLDER AS ZONAL FLOW BUCKLES
WITH A DEVELOPING LONG WAVE TROUGH OVER THE WEST AND THE FLOW
SHIFTING FROM THE PACIFIC TO CANADA. THERE IS CONSIDERABLE MODEL
SPREAD WITH THE FEATURES WITHIN THE LONG WAVE TROUGH. THERE IS
POTENTIAL FOR A MUCH MORE SIGNIFICANT SPREAD OF PRECIPITATION...JUST
AS THERE IS POTENTIAL FOR THE ZONAL NATURE OF THE FLOW TO HOLD OUT
WITH LESS DIGGING OF THE MEAN TROUGH WITH THE PASSAGE OF A SERIES
OF SHORT WAVE TROUGHS. THE MODELS A FAR APART TO THE NORTH...ACROSS
CANADA AND TO THE WEST ACROSS THE EASTERN PACIFIC AND GULF OF
ALASKA BY FRIDAY. THE MAIN STORY THURSDAY AND FRIDAY WILL BE
COLDER AND MAYBE SNOW SHOWERS...OR MORE ORGANIZED PRECIPITATION
ACROSS THE NORTH AND EAST. MODELS ARE QUITE CHAOTIC ON SATURDAY SO
HAVE MAINLY A PERSISTENCE FORECAST WITH LOWER VALLEY POPS THEN BUT
LITTLE CHANGE IN TEMPERATURES. THIS MAKES FOR LOW CONFIDENCE IN
THE EXTENDED AFTER WEDNESDAY.

&&

.AVIATION...
A WEAK DISTURBANCE IN THE STRONG UPPER WESTERLY FLOW WILL CAUSE A
CLOUD DECK WITH A BASE OF 5K TO PERSIST ACROSS NORTHWEST WY THROUGH
03Z THIS EVENING WITH LOCAL CIGS OF 3K INCLUDING THE VCNTY OF KJAC.
PATCHY LIGHT VALLEY RAIN AND MOUNTAIN SNOW WILL CAUSE LOCAL MVFR
CONDITIONS AND MOUNTAIN OBSCURATIONS THROUGH 03Z IN NW WY. FROM 03Z
THIS EVENING THROUGH 18Z SUNDAY ANY LINGERING MVFR CONDITIONS AND
LOCAL MOUNTAIN OBSCURATIONS WILL BE RESTRICTED TO THE HIGHER TERRAIN
OF NORTHWEST MOUNTAIN. VFR CONDITIONS ARE EXPECTED OTHERWISE. WEST
WINDS OF 15 TO 25 MPH WILL OCCUR OVER PORTIONS OF CENTRAL AND
SOUTHERN WY AND OVER THE HIGHER TERRAIN EARLY THIS EVENING AND
SUNDAY.

&&

.FIRE WEATHER...
A MODERATE TO STRONG SOUTHWEST FLOW ALOFT WILL CONTINUE TO BRING
SCATTERED SNOW SHOWERS TO WESTERN AREAS WITH BREEZY WARM
CONDITIONS EAST OF THE DIVIDE. A DRY WEST TO EAST FLOW IS EXPECTED
ON SUNDAY WITH A WEAK PACIFIC STORM SYSTEM CLIPPING SOUTHERN
WYOMING MONDAY MORNING...WITH ONLY A SLIGHT CHANCE FOR ISOLATED LIGHT
SHOWERS IN CENTRAL AND EASTERN SWEETWATER COUNTY MONDAY MORNING. A
MAINLY DRY SOUTHWESTERLY FLOW WILL REMAIN OVER THE DISTRICT
THROUGH AT LEAST TUESDAY.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...CHURCH
LONG TERM...C.BAKER
AVIATION...LIPSON
FIRE WEATHER...CHURCH

000
FXUS65 KCYS 072148
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
248 PM MST SAT NOV 7 2009

.SHORT TERM...WATER VAPOR LOOP SHOWS A SHORTWAVE DIGGING INTO THE
INTERMOUNTAIN WEST THIS AFTERNOON. MSAS SFC PRESSURE ANALYSIS
SHOWS WIDESPREAD PRESSURE FALLS ACROSS THE ROCKIES AHEAD OF THE
WAVE...WITH LEESIDE SFC TROUGH BECOMING APPARENT. BREEZY SOUTHERLY
SFC WINDS HAVE BECOME WIDESPREAD ACROSS THE CWA THIS EARLY
AFTERNOON AS THE LEE TROUGH DEEPENS. A PLUME OF MID AND HIGH LEVEL
MOISTURE IS MOVING THROUGH THE ROCKIES IN STRONG SOUTHWEST FLOW
ALOFT THIS AFTERNOON...SO HAVE PARTLY CLOUDY SKIES WITH EMBEDDED
MOUNTAINS WAVES WHICH CAN BE SEEN ON VISIBLE SATELLITE IMAGERY.
TEMPS ACROSS THE BOARD ARE ONCE AGAIN MILD...ALTHOUGH COOLER THAN
PREVIOUS DAYS. AS THE UPPER LEVEL WAVE MOVES ACROSS NORTHERN
WYOMING...EXPECT OROGRAPHIC SHOWERS TO INCREASE THROUGH THE
EVENING. TEMPERATURES IN THE HIGH TERRAIN BASED ON MESOWEST SITES
ARE WARM ENOUGH TO SUGGEST A MIX OF RAIN/SNOW INITIALLY WHICH
SHOULD CHANGE OVER TO ALL SNOW AS TEMPS COOL OVERNIGHT.
ACCUMULATIONS SHOULD REMAIN LIGHT OVERALL. ANOTHER SHORTWAVE WILL
MOVE ACROSS THE REGION OVERNIGHT WITH A DRY COLD FRONT MOVING THROUGH
THE EASTERN ZONES EARLY SUNDAY MORNING. TEMPS WILL AGAIN BE COOLER
TOMORROW AND NW WINDS WILL INCREASE BEHIND THE FRONT AS HIGH
PRESSURE AT THE SFC BUILDS ACROSS THE INTERMOUNTAIN WEST. 12Z NAM
SHOWS MUCH STRONGER WINDS THAN EITHER THE GFS...ECMWF OR CANADIAN
MODELS SO WILL RELY MORE ON THE MODEL CONSENSUS THEN THE OUTLIER
NAM. IT SHOULD STILL BE A BREEZY DAY ACROSS THE EASTERN ZONES
THOUGH WITH LOCAL SPOTS GUSTING 30 MPH IN SOUTHERN PORTIONS OF
SOUTHEAST WYOMING AND THE NEBRASKA PANHANDLE. YET ANOTHER
SHORTWAVE WILL MOVE ACROSS THE REGION SUNDAY NIGHT INTO MONDAY.
WITH LOW LEVEL UPSLOPE WINDS IN PLACE ACROSS THE SOUTHERN CWA IN
ADDITION TO SUPPORT FROM THE UPPER WAVE...WILL SEE PRECIPITATION
ACROSS THIS AREA INCREASE IN COVERAGE THROUGH THE NIGHT. WILL SEE
SNOW IN THE HIGHER ELEVATIONS WITH RAIN OR A RAIN/SNOW MIX LIKELY
FURTHER EAST AS THICKNESSES DO NOT DECREASE SUBSTANTIALLY WITH THE
PASSING WAVE. TOTAL PRECIP ACCUMULATIONS SHOULD BE LIGHT AS THE
UPPER LEVEL SUPPORT QUICKLY TRANSLATES EAST OF THE AREA BY MONDAY
AFTERNOON AND UPSLOPE FLOW WEAKENS.

&&

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY...
UPPER RIDGE AXIS WILL MOVE EAST OUT ONTO THE CENTRAL PLAINS MONDAY
NIGHT...TURNING THE MID/UPPER-LEVEL FLOW SOUTHWESTERLY INTO THE
INTERMOUNTAIN WEST. THIS PATTERN WILL INDUCE THERMAL RIDGING ACROSS
THE REGION...WHICH WILL BE MAXIMIZED LATE TUESDAY. BENIGN CONDITIONS
WILL OCCUR FOR MONDAY NIGHT THROUGH TUESDAY...WITH TEMPERATURES
WARMING BACK ABOVE NORMAL AFTER A COOLER MONDAY. MEDIUM RANGE
DETERMINISTIC MODEL OUTPUT FROM 12Z ARE BECOMING MORE CONGRUENT FOR
THE WEDNESDAY THROUGH FRIDAY TIMEFRAME...BUT THEN BECOME OUT OF
PHASE BY THE WEEKEND. UPPER LOW WILL DIG INTO THE ERN PACIFIC EARLY
WEDNESDAY...WITH INITIAL SHORTWAVE ENERGY REACHING THE ID/WY BORDER
BY LATE WEDNESDAY. THE ECMWF WAS THE SLOWEST WITH THIS ENERGY...
HOLDING IT BACK NR THE CASCADES BY THIS TIME. CONTINUED THE EARLIER
THINKING OF SPREADING PRECIPITATION CHANCES FIRST INTO THE
SNOWY/SIERRA MADRES ON WEDNESDAY...THEN OUT INTO LOWER ELEVATIONS OF
CARBON AND ALBANY COUNTIES WEDNESDAY NIGHT...AND FINALLY OUT ONTO
THE ERN PLAINS BY THURSDAY. THE GFS/GEM SUPPORT THE IDEA OF BRINGING
THE MAIN TROUGH INTO WRN WY BY EARLY FRIDAY...ALTHOUGH THE GEM
CLOSES IT OFF OVER IDAHO. MEANWHILE...THE ECMWF WOULD SUGGEST A
SPLIT FLOW PATTERN...WHICH IF VERIFIES WOULD LIMIT PRECIPITATION
CHANCES ACROSS THE REGION. SO...ALLOWING FOR SOME UNCERTAINTY IN THE
PATTERN...HAVE INCREASE PRECIPITATION CHANCES SOME DURING THE
THURSDAY NIGHT THROUGH FRIDAY PERIOD. LIKEWISE...AFTER ABOVE AVERAGE
TEMPERATURES TUESDAY AND WEDNESDAY...COOLER TEMPERATURES ARE IN
STORE FOR THURSDAY THROUGH SATURDAY. PREFRONTAL WINDS INCREASE ABOVE
50 KNOTS AT H7 LATE WEDNESDAY/EARLY THURSDAY...SO THIS PERIOD WILL
HAVE BE MONITORED CLOSELY FOR THE POTENTIAL FOR HIGH WINDS AT THE
SURFACE. INITIAL PRECIPITATION WILL LIKELY BE IN THE FORM OF RAIN AT
ALL LOWER ELEVATIONS THROUGH THURSDAY...WITH BEST COLD AIR ADVECTION
AND ANY POTENTIAL CHANGE-OVER HOLDING OFF UNTIL DURING THE DAY ON
FRIDAY.

&&

.AVIATION...A WEAK DISTURBANCE WILL DRAG A WEAK...AND MOSTLY DRY...COLD FRONT
THROUGH THE REGION TONIGHT. ONLY IMPACT AT AREA TERMINALS WILL BE A
WIND SWITCH FROM PREDOMINATELY S/SE EAST OF THE LARAMIE RANGE...AND
SW WEST OF THE LARAMIE RANGE...TO AN EVENTUAL NORTHWEST BEHIND THE
FRONT. BROUGHT CIGS DOWN SOMEWHAT OVERNIGHT...BUT MAINTAINED VFR
CONDITIONS AT ALL TERMINALS. CIGS WILL BEGIN TO INCREASE DURING THE
DAY ON SUNDAY...AS THE UPPER LEVEL DISTURBANCE DEPARTS.

&&

.FIRE WEATHER...NORTHWEST WINDS WILL INCREASE EARLY SUNDAY ACROSS
EASTERN ZONES AND WILL CONTINUE THROUGH THE EVENING. SOME AREAS
COULD SEE GUSTS AROUND 30 MPH...WITH STRONGEST WINDS IN EXTREME
SOUTHEAST WYOMING AND THE SOUTHERN NEBRASKA PANHANDLE. WITH COOLER
TEMPS BEHIND A FRONT MOVING THROUGH THE AREA TONIGHT...MINIMUM
RELATIVE HUMIDITIES SHOULD REMAIN IN THE 20S AND 30S IN THIS AREA
FOR SUNDAY. WILL SEE PRECIPITATION INCREASE IN COVERAGE SUNDAY NIGHT
INTO MONDAY AS AN UPPER LEVEL WAVE MOVES ACROSS THE REGION. WILL
SEE SNOW IN THE MOUNTAINS WITH MAINLY RAIN OR A RAIN/SNOW MIX IN
THE LOWER ELEVATIONS OF WYOMING AND THE NEBRASKA PANHANDLE.
OVERALL ACCUMULATIONS OF PRECIPITATION WILL BE LIGHT THROUGH EARLY
MONDAY AFTERNOON.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.

&&

$$

SHORT TERM/FIRE WEATHER...RJM
LONG TERM/AVIATION...HAHN

000
FXUS63 KUNR 072056
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
156 PM MST SAT NOV 7 2009

.DISCUSSION...CURRENT SURFACE MAP PLACES HIGH PRESSURE ACROSS
EASTERN SOUTH DAKOTA...WITH WEAK TROF ACROSS EASTERN WYOMING.
SHORTWAVE MOVING INTO THE PACIFIC NORTHWEST WILL MOVE ACROSS
NORTHERN ROCKIES TONIGHT...AND ACROSS ND ON SUNDAY. MODELS
CONTINUE TO SHOW WEAK LIFT/MARGINAL QPF ACROSS NW SD TONIGHT...SO
WILL LEAVE IN ISOLATED SHOWERS. DRY WEATHER SUNDAY AS COLD FRONT
MOVES THROUGH. WARMER ON MONDAY WITH UPPER LEVEL RIDGING.

EXTENDED...MAINLY DRY AND MILD WEATHER IS EXPECTED INTO THE MIDDLE
PART OF NEXT WEEK AS AN UPPER LEVEL RIDGE PASSES OVER THE AREA.
TEMPS WILL GENERALLY BE ABOVE SEASONAL AVERAGES. NEXT CHANCE FOR
PRECIPITATION LOOKS TO BE LATE THURSDAY INTO FRIDAY AS NEXT UPPER
TROF DIGS INTO THE NORTHERN ROCKIES. OPERATIONAL GFS DIFFERS FROM
ITS ENSEMBLE MEMBERS AND LATEST EC WITH TIMING OF THIS TROF. OP GFS
BRINGS TROF THROUGH MUCH EARLIER...WHILE OTHER SOLNS KEEP RIDGING
OVER THE NORTHERN PLAINS THROUGH WEDNESDAY. WILL SIDE WITH SLOWER
SOLN FOR THE EXTENDED. TEMPERATURES WILL COOL TO NEAR AVERAGE LATE
IN THE WEEK.

&&

.AVIATION...VFR CONDITIONS CAN BE EXPECTED THROUGH THE FORECAST
PERIOD.

&&




&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

000
FXUS65 KRIW 071610
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
910 AM MST SAT NOV 7 2009

.UPDATE...
JUST SENT QUICK UPDATE TO INCREASE CLOUD COVER AND INTRODUCE A
SLIGHT CHANCE FOR LIGHT RAIN IN THE NORTHERN BIG HORN BASIN THIS
MORNING WITH KGEY ASOS REPORTING LIGHT RAIN. STRONG MID AND UPPER
LEVEL DIFLUENCE ASSOCIATED WITH A 110KT JET STREAK OVER NORTHEAST
WYOMING PRODUCING THE LARGE 12-13K FEET AGL CLOUD DECK EAST OF THE
DIVIDE THIS MORNING. THE JET STREAK AND ASSOCIATED CLOUD DECK WILL
GRADUALLY TRANSLATE EAST OF THE AREA DURING THE AFTERNOON.

&&

.PREV DISCUSSION... /ISSUED 308 AM MST SAT NOV 7 2009/

SHORT TERM...TODAY THROUGH MONDAY NIGHT

SHORTWAVE APPROACHING THE PAC WEST COAST THIS MORNING WITH BACKING
SOUTHWEST FLOW OVER WYOMING.  JET STRENGTHENING AS WELL OVER THE
NORTHERN PLAINS AND ACROSS MONTANA.  RIGHT ENTRANCE REGION SETTING
UP OVER NORTHERN WYOMING AS WELL OFFERING SOME LIFT.  THIS WILL KEEP
THE SHOWERS GOING THERE TODAY...THOUGH THE MOISTURE FETCH WILL BE
LIMITED.  CLOUD TOPS COOLING EARLY THIS MORNING WITH PERHAPS A BIT
OF A WEAK BAROCLINIC LEAF FORMING UNDER THE BACKING FLOW AND JET
DYNAMICS.  HOWEVER...RADAR ECHOES ON THE DECREASE.  SOME SOUTHWEST
WINDS WILL CONTINUE TODAY BUT WILL BE MUCH LESS THAN THE PAST FEW
DAYS.  THE SHORTWAVE MOVES THROUGH THIS AFTERNOON AND EVENING WITH
DRYING AIR MOVING IN OVERNIGHT ENDING THE SHOWER ACTIVITY.  WILL
ALSO SEE CLOUDS DISSIPATE AS WELL.  ZONAL FLOW REMAINS OVER WYOMING
SUNDAY WITH RELATIVELY LIGHT WINDS AT THE SURFACE.  WILL HAVE SOME
HIGH CLOUDS MOVING THROUGH AS HIGH LEVEL MOISTURE MOVES THROUGH.
RIDGE BUILDS IN FOR MONDAY WITH DRY CONDITIONS AND LIGHT WINDS
CONTINUING.  RIDGE SHIFTS EAST MONDAY NIGHT AS THE NEXT PACIFIC
TROUGH APPROACHES.  THIS WILL ALLOW THE SOUTHWEST GRADIENT TO
DEVELOP AS THE LEE TROUGH DEVELOPS.  TEMPERATURES WILL BE MILD TODAY
OVER MOST OF THE AREA THOUGH COOLER THAN YESTERDAY.  THEY COOL A
LITTLE FOR TOMORROW AND MONDAY...WITH NEAR NORMAL READINGS.

LONG TERM...TUESDAY THROUGH SATURDAY

FAST PROGRESSIVE ZONAL FLOW WITH A BROAD FLAT TROUGH WILL EXTEND
FROM THE EASTERN PACIFIC ACROSS THE PACIFIC NORTHWEST...THE
NORTHERN GREAT BASIN AND ACROSS WYOMING INTO THE NORTHERN AND
CENTRAL PLAINS. A SERIES OF FAST MOVING SHORT WAVE TROUGHS WILL
BRING PACIFIC MOISTURE INTO THE WESTERN MOUNTAINS BRINGING LOCAL
SHOWERS TO THE WESTERN MOUNTAINS, THIS WILL BRING BREEZY AREAS
EAST OF THE CONTINENTAL DIVIDE AND ACROSS THE SOUTH.  TUESDAY THE
FLOW BACKS AHEAD OF A DEEPENING PACIFIC TROUGH. WIND SHOULD PICK
UP AND TEMPERATURES SHOULD RISE. PACIFIC MOISTURE REMAINS TO THE
WEST UNTIL WEDNESDAY AS THE PACIFIC TROUGH MOVES INLAND.
PRECIPITATION... MAINLY SNOW WITH SOME RAIN IN THE VALLEYS WILL
MOVE INTO THE WEST, WINDS WILL PICK UP EAST OF THE DIVIDE.
THURSDAY THE TROUGH WILL PASS TROUGH THEN FOLLOWED BY A CANADIAN
TROUGH. THIS WILL SPREAD THE THREAT OF PRECIPITATION EAST OF THE
DIVIDE. MODELS HAVE BEEN INCONSISTENT WITH THE STRENGTH OF THE
CLIPPER TROUGH AND THE AMOUNT OF PRECIPITATION WITH IT. FORECAST
RATHER CONSERVATIVE AT THIS TIME DUE TO MODEL FLIP FLOPS. SHOULD
BE COLDER AS ZONAL FLOW BUCKLES WITH A DEVELOPING LONG WAVE TROUGH
OVER THE WEST AND THE FLOW SHIFTING FROM THE PACIFIC TO CANADA.
THERE IS CONSIDERABLE MODEL SPREAD WITH THE FEATURES WITHIN THE
LONG WAVE TROUGH. THERE IS POTENTIAL FOR A MUCH MORE SIGNIFICANT
SPREAD OF PRECIPITATION...JUST AS THERE IS POTENTIAL FOR THE ZONAL
NATURE OF THE FLOW TO HOLD OUT WITH LESS DIGGING OF THE MEAN
TROUGH WITH THE PASSAGE OF A SERIES OF SHORT WAVE TROUGHS. THE
MODELS A FAR APART TO THE NORTH...ACROSS CANADA AND TO THE WEST
ACROSS THE EASTERN PACIFIC AND GULF OF ALASKA BY FRIDAY. THE MAIN
STORY THURSDAY AND FRIDAY WILL BE COLDER AND MAYBE SNOW
SHOWERS...OR MORE ORGANIZED PRECIPITATION ACROSS THE NORTH AND
EAST. MODELS ARE QUITE CHAOTIC ON SATURDAY SO HAVE MAINLY A
PERSISTENCE FORECAST WITH LOWER VALLEY POPS THEN BUT LITTLE CHANGE
IN TEMPERATURES.  THIS MAKES FOR LOW CONFIDENCE IN THE EXTENDED
AFTER WEDNESDAY.

AVIATION...

VFR CONDITIONS WILL PREVAIL ACROSS MOST OF THE AREA THROUGH 12Z
SUNDAY WITH LOCAL MVFR CONDITIONS AND OCCASIONAL MOUNTAIN
OBSCURATIONS VCNTY AND NORTH OF A KJAC-KCOD LINE.  A FETCH OF
MOISTURE WILL REMAIN JUST SOUTH OF A JET STREAM AXIS...ACROSS IDAHO
INTO NORTHWEST WYOMING.  AREAS OF MOUNTAIN SNOW AND LOCAL VALLEY
LIGHT RAIN/SNOW...SNOW LEVELS AROUND 7KFT WILL BE ENCOUNTERED IN THE
NORTHWEST.  BKN CLOUD DECKS 120-130MSL WILL EXTEND SOUTH TO VCNTY
KBPI/KPNA.  AN UPPER LEVEL DISTURBANCE WILL MOVE INTO THE WEST
AROUND 00Z SUNDAY WITH IMPROVING CONDITIONS BEHIND THIS SYSTEM.
THIS SYSTEM WILL SPREAD SCT-BKN120-150MSL CLOUD DECKS EAST OF THE
DIVIDE 00Z-08Z SUNDAY.

FIRE WEATHER...

SOUTHWEST WINDS WILL CONTINUE TODAY OVER MUCH OF THE AREA THOUGH
LESS SPEED THAN YESTERDAY.  SHOWERS WILL CONTINUE OVER THE NORTHWEST
AS WELL TODAY.  DRIER AIR MOVES IN TONIGHT WITH DRY CONDITIONS WITH
LIGHT WINDS EXPECTED FOR SUNDAY.  IT WILL BE A LITTLE COOLER...BUT
STILL AROUND NORMAL.  MONDAY WILL BE NICE DAY AS WELL.  WINDS WILL
BEGIN TO INCREASE MONDAY NIGHT AND TUESDAY AS THE NEXT PACIFIC
TROUGH APPROACHES.  THIS SYSTEM LOOKS TO BRING WIND AND
PRECIPITATION TO THE REGION MID NEXT WEEK.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...CHURCH
SHORT TERM...TWB
AVIATION...AEM
LONG TERM...C.BAKER

000
FXUS65 KCYS 071106
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
406 AM MST SAT NOV 7 2009

.SHORT TERM...
GENERALLY MILD AND MAINLY DRY WEATHER EXPECTED ACROSS THE CWA DURING
THE PERIOD.  VARYING AMOUNTS OF MAINLY HIGH CLOUDS EXPECTED AS
DECENT HIGH LEVEL MOISTURE CONTINUES ACROSS THE REGION ON WSW UPPER
FLOW WITH SOME LEE ENHANCEMENT...EVIDENT NOW OVER FAR SE WY INTO THE
NEB PANHANDLE.  LESS WIND TODAY WITH MODEST SFC TROF DEVELOPING
ALONG THE MTNS.  SHORTWAVE ENERGY MOVING ACROSS THE NORTHERN ROCKYS
LATER TODAY AND TONIGHT WILL PUSH A PACIFIC COOL FRONT ACROSS THE
CWA OVERNIGHT WITH MAXS SUNDAY ABOUT 5-8 DEGREES LESS THAN TODAY.
RATHER DRY AIR MASS WILL HINDER PCPN WITH LATEST NAM SHOWING ONLY A
BIT OF LIGHT PCPN OVER THE HIGHER MTNS LATER TONIGHT.

.LONG TERM...
AN UPPER LEVEL SHORTWAVE WILL IMPACT THE AREA ON SUNDAY NIGHT INTO
MONDAY MORNING. BOTH THE ECMWF AND GFS INDICATE PRECIPITATION
EXTENDING FROM THE SIERRA MADRE MOUNTAIN RANGE EASTWARD THROUGH
THE SOUTHERN NEBRASKA PANHANDLE BY ON MONDAY MORNING. THERE WILL
BE SNOW IN THE HIGHER TERRAIN...BUT LITTLE ACCUMULATION. ALL
MEMBERS FROM THE SREF FORECAST FOR SCOTTSBLUFF INDICATE THE
PRECIPITATION TYPE AS RAIN. THUS ANTICIPATE THERE WILL BE SNOW AND
RAIN MIX EARLY IN THE MORNING ACROSS LARAMIE COUNTY WITH RAIN
FURTHER EAST. THROUGH MONDAY MORNING RAIN AND SNOW MIX WILL
TRANSITION INTO RAIN. EXPECT SHOWERS TO DIMINISH THROUGH THE LATE
MORNING. TEMPERATURES WILL BE COOLER WITH HIGHS IN THE UPPER 40S
TO LOWER 50S ON MONDAY.

HIGH PRESSURE WILL REGAIN STRENGTH ON TUESDAY AND WEDNESDAY WITH
HIGH TEMPERATURES REBOUNDING INTO THE UPPER 50S AND LOWER 60S. 500
MB HEIGHT ANOMALIES FROM THE GEFS INDICATE AROUND ONE STANDARD
DEVIATION WARMER THAN THE CLIMATOLOGY FOR TUESDAY AND WEDNESDAY.
THUS EXPECT DRY CONDITIONS THROUGH MID WEEK. MODELS TEND TO DIFFER
BY MID WEEK WITH THE GEM MODEL INDICATING A CLOSED OFF UPPER LEVEL
LOW OFF THE WEST COAST AND THE GFS AND ECMWF INDICATING OPEN WAVE
TROUGHS. BOTH THE GFS AND ECMWF HAVE TIMING ISSUES AS WELL.
LOOKING AT THE GFS ENSEMBLE FORECAST SYSTEM SHOWS A VARIETY OF
MODEL SOLUTIONS AMONG THE MEMBERS IN DEVELOPING THIS UPPER LEVEL
SYSTEM ON THURSDAY INTO NEXT WEEKEND. THE GFS 00Z MODEL RUN
COMPLETELY DIFFERS IN THE QPF AMOUNT ACROSS THE AREA COMPARED TO
THE LATEST 06Z RUN. ALSO THE ECMWF INDICATES SOME QPF BUT NOT SURE
IF THE WARRANTED HIGHER POPS IN THE CURRENT FORECAST. THUS
HAVE DROPPED THE POPS MORE IN LINE WITH THE CLIMATOLOGICAL POPS
FOR THE AREA GIVEN THE UNCERTAINTY. AT THIS TIME...CERTAINLY DO
NOT WANT TO EVEN CONSIDER THE SNOW VERSUS RAIN ISSUES WITH THE
SYSTEM NEXT WEEK.

&&

.AVIATION...VFR CONDITIONS EXPECTED ACROSS THE AREA THOUGH SUNDAY.
SFC COOL FRONT WILL PASS ACROSS TONIGHT WITH A FEW MTNS SNOW SHOWERS
POSSIBLE LATE TONIGHT/EARLY SUNDAY.

&&

.FIRE WEATHER...NO CONCERNS SEEN WITH LESS WIND AND COOLER
TEMPERATURES THROUGH SUNDAY.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.

&&

$$

SHORT TERM/AVIATION...RE
LONG TERM...MAK

000
FXUS63 KUNR 071038
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
340 AM MST SAT NOV 7 2009

.DISCUSSION...10Z SFC ANALYSIS SHOWS A WEAK TROUGH EXTENDING FROM
LATE SUPERIOR INTO SOUTHWESTERN KANSAS WITH WEAK HIGH PRESSURE OVER
THE NORTHERN PLAINS. UPPER AIR ANALYSIS SHOWS A FEW WEAK SHORTWAVE
EMBEDDED IN ZONAL FLOW OVER THE AREA.

HIGH TEMPERATURES TODAY WILL RANGE FROM 10 TO 15 DEGREES COOLER THAN
YESTERDAY DUE TO HIGH PRESSURE THAT MOVED IN BEHIND A WEAK COLD
FRONT OVERNIGHT. LIGHT WINDS WILL BE FOUND ACROSS MUCH OF THE AREA
THIS MORNING DUE TO THE HIGH PRESSURE. AS THE HIGH MOVES EAST
TODAY...SOUTHEASTERLY WINDS WILL INCREASE ACROSS NORTHEASTERN
WYOMING AND WESTERN SOUTH DAKOTA. A SHORTWAVE WILL CROSS THE
NORTHERN PLAINS TONIGHT WHICH WILL INTERACT WITH A WEAK SURFACE
BOUNDARY OVER FAR NORTHEASTERN WYOMING AND FAR NORTHWESTERN SOUTH
DAKOTA. THERE MAY BE ENOUGH FORCING FOR SOME LIGHT PRECIPITATION TO
DEVELOP OVER THOSE AREAS SO HAVE INCLUDED A SLIGHT CHANCE OF
PRECIPITATION TONIGHT.

TEMPERATURES WILL REMAIN SLIGHTLY WARMER THAN NORMAL ON SUNDAY AND
MONDAY. A COUPLE MORE SHORTWAVES WILL CROSS THE AREA...BUT
MODELS CONTINUE TO INDICATE JUST AN INCREASE IN MID AND HIGH CLOUD
COVER WITH DRY AIR IN THE LOWER LEVELS.

EXTENDED...MAINLY DRY AND MILD WEATHER IS EXPECTED INTO THE MIDDLE
PART OF NEXT WEEK AS AN UPPER LEVEL RIDGE PASSES OVER THE AREA.
TEMPS WILL GENERALLY BE ABOVE SEASONAL AVERAGES. NEXT CHANCE FOR
PRECIPITATION LOOKS TO BE WEDNESDAY NIGHT INTO THURSDAY AS NEXT
SHORTWAVE APPROACHES. TEMPERATURES WILL COOL TO NEAR AVERAGE LATE IN
THE WEEK.

&&

.AVIATION...VFR CONDITIONS CAN BE EXPECTED THROUGH THE FORECAST
PERIOD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

000
FXUS65 KRIW 071008
AFDRIW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RIVERTON WY
308 AM MST SAT NOV 7 2009

.SHORT TERM...TODAY THROUGH MONDAY NIGHT

SHORTWAVE APPROACHING THE PAC WEST COAST THIS MORNING WITH BACKING
SOUTHWEST FLOW OVER WYOMING.  JET STRENGTHENING AS WELL OVER THE
NORTHERN PLAINS AND ACROSS MONTANA.  RIGHT ENTRANCE REGION SETTING
UP OVER NORTHERN WYOMING AS WELL OFFERING SOME LIFT.  THIS WILL KEEP
THE SHOWERS GOING THERE TODAY...THOUGH THE MOISTURE FETCH WILL BE
LIMITED.  CLOUD TOPS COOLING EARLY THIS MORNING WITH PERHAPS A BIT
OF A WEAK BAROCLINIC LEAF FORMING UNDER THE BACKING FLOW AND JET
DYNAMICS.  HOWEVER...RADAR ECHOES ON THE DECREASE.  SOME SOUTHWEST
WINDS WILL CONTINUE TODAY BUT WILL BE MUCH LESS THAN THE PAST FEW
DAYS.  THE SHORTWAVE MOVES THROUGH THIS AFTERNOON AND EVENING WITH
DRYING AIR MOVING IN OVERNIGHT ENDING THE SHOWER ACTIVITY.  WILL
ALSO SEE CLOUDS DISSIPATE AS WELL.  ZONAL FLOW REMAINS OVER WYOMING
SUNDAY WITH RELATIVELY LIGHT WINDS AT THE SURFACE.  WILL HAVE SOME
HIGH CLOUDS MOVING THROUGH AS HIGH LEVEL MOISTURE MOVES THROUGH.
RIDGE BUILDS IN FOR MONDAY WITH DRY CONDITIONS AND LIGHT WINDS
CONTINUING.  RIDGE SHIFTS EAST MONDAY NIGHT AS THE NEXT PACIFIC
TROUGH APPROACHES.  THIS WILL ALLOW THE SOUTHWEST GRADIENT TO
DEVELOP AS THE LEE TROUGH DEVELOPS.  TEMPERATURES WILL BE MILD TODAY
OVER MOST OF THE AREA THOUGH COOLER THAN YESTERDAY.  THEY COOL A
LITTLE FOR TOMORROW AND MONDAY...WITH NEAR NORMAL READINGS.

.LONG TERM...TUESDAY THROUGH SATURDAY

FAST PROGRESSIVE ZONAL FLOW WITH A BROAD FLAT TROUGH WILL EXTEND
FROM THE EASTERN PACIFIC ACROSS THE PACIFIC NORTHWEST...THE
NORTHERN GREAT BASIN AND ACROSS WYOMING INTO THE NORTHERN AND
CENTRAL PLAINS. A SERIES OF FAST MOVING SHORT WAVE TROUGHS WILL
BRING PACIFIC MOISTURE INTO THE WESTERN MOUNTAINS BRINGING LOCAL
SHOWERS TO THE WESTERN MOUNTAINS, THIS WILL BRING BREEZY AREAS
EAST OF THE CONTINENTAL DIVIDE AND ACROSS THE SOUTH.  TUESDAY THE
FLOW BACKS AHEAD OF A DEEPENING PACIFIC TROUGH. WIND SHOULD PICK
UP AND TEMPERATURES SHOULD RISE. PACIFIC MOISTURE REMAINS TO THE
WEST UNTIL WEDNESDAY AS THE PACIFIC TROUGH MOVES INLAND.
PRECIPITATION... MAINLY SNOW WITH SOME RAIN IN THE VALLEYS WILL
MOVE INTO THE WEST, WINDS WILL PICK UP EAST OF THE DIVIDE.
THURSDAY THE TROUGH WILL PASS TROUGH THEN FOLLOWED BY A CANADIAN
TROUGH. THIS WILL SPREAD THE THREAT OF PRECIPITATION EAST OF THE
DIVIDE. MODELS HAVE BEEN INCONSISTENT WITH THE STRENGTH OF THE
CLIPPER TROUGH AND THE AMOUNT OF PRECIPITATION WITH IT. FORECAST
RATHER CONSERVATIVE AT THIS TIME DUE TO MODEL FLIP FLOPS. SHOULD
BE COLDER AS ZONAL FLOW BUCKLES WITH A DEVELOPING LONG WAVE TROUGH
OVER THE WEST AND THE FLOW SHIFTING FROM THE PACIFIC TO CANADA.
THERE IS CONSIDERABLE MODEL SPREAD WITH THE FEATURES WITHIN THE
LONG WAVE TROUGH. THERE IS POTENTIAL FOR A MUCH MORE SIGNIFICANT
SPREAD OF PRECIPITATION...JUST AS THERE IS POTENTIAL FOR THE ZONAL
NATURE OF THE FLOW TO HOLD OUT WITH LESS DIGGING OF THE MEAN
TROUGH WITH THE PASSAGE OF A SERIES OF SHORT WAVE TROUGHS. THE
MODELS A FAR APART TO THE NORTH...ACROSS CANADA AND TO THE WEST
ACROSS THE EASTERN PACIFIC AND GULF OF ALASKA BY FRIDAY. THE MAIN
STORY THURSDAY AND FRIDAY WILL BE COLDER AND MAYBE SNOW
SHOWERS...OR MORE ORGANIZED PRECIPITATION ACROSS THE NORTH AND
EAST. MODELS ARE QUITE CHAOTIC ON SATURDAY SO HAVE MAINLY A
PERSISTENCE FORECAST WITH LOWER VALLEY POPS THEN BUT LITTLE CHANGE
IN TEMPERATURES.  THIS MAKES FOR LOW CONFIDENCE IN THE EXTENDED
AFTER WEDNESDAY.

&&

.AVIATION...

VFR CONDITIONS WILL PREVAIL ACROSS MOST OF THE AREA THROUGH 12Z
SUNDAY WITH LOCAL MVFR CONDITIONS AND OCCASIONAL MOUNTAIN
OBSCURATIONS VCNTY AND NORTH OF A KJAC-KCOD LINE.  A FETCH OF
MOISTURE WILL REMAIN JUST SOUTH OF A JET STREAM AXIS...ACROSS IDAHO
INTO NORTHWEST WYOMING.  AREAS OF MOUNTAIN SNOW AND LOCAL VALLEY
LIGHT RAIN/SNOW...SNOW LEVELS AROUND 7KFT WILL BE ENCOUNTERED IN THE
NORTHWEST.  BKN CLOUD DECKS 120-130MSL WILL EXTEND SOUTH TO VCNTY
KBPI/KPNA.  AN UPPER LEVEL DISTURBANCE WILL MOVE INTO THE WEST
AROUND 00Z SUNDAY WITH IMPROVING CONDITIONS BEHIND THIS SYSTEM.
THIS SYSTEM WILL SPREAD SCT-BKN120-150MSL CLOUD DECKS EAST OF THE
DIVIDE 00Z-08Z SUNDAY.

&&

.FIRE WEATHER...

SOUTHWEST WINDS WILL CONTINUE TODAY OVER MUCH OF THE AREA THOUGH
LESS SPEED THAN YESTERDAY.  SHOWERS WILL CONTINUE OVER THE NORTHWEST
AS WELL TODAY.  DRIER AIR MOVES IN TONIGHT WITH DRY CONDITIONS WITH
LIGHT WINDS EXPECTED FOR SUNDAY.  IT WILL BE A LITTLE COOLER...BUT
STILL AROUND NORMAL.  MONDAY WILL BE NICE DAY AS WELL.  WINDS WILL
BEGIN TO INCREASE MONDAY NIGHT AND TUESDAY AS THE NEXT PACIFIC
TROUGH APPROACHES.  THIS SYSTEM LOOKS TO BRING WIND AND
PRECIPITATION TO THE REGION MID NEXT WEEK.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...TWB
LONG TERM...C.BAKER
AVIATION...AEM
FIRE WEATHER...TWB

000
FXUS63 KUNR 070235
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
735 PM MST FRI NOV 6 2009

.DISCUSSION...02Z SURFACE ANALYSIS HAD COOL FRONT FROM KBIS TO
K2WX TO KSHR...MOVING SOUTHEAST. IT HAS A 4-5MB/3HR PRESSURE RISE
BUBBLE WITH IT...CREATING SOME 40KT GUSTS AS IT COMES THROUGH.
WILL UPDATE FORECAST TO BRING WINDS UP WITH FRONTAL PASSAGE FOR A
COUPLE OF HOURS. REST OF FORECAST IN GOOD SHAPE.

&&

.PREV DISCUSSION... /ISSUED 155 PM MST FRI NOV 6 2009/

DISCUSSION...CURRENT SURFACE MAP PLACES TROF ACROSS CENTRAL
DAKOTAS. DEEP MIXING AND ABUNDANT SUNSHINE HAS ALLOWED FOR RECORD
TEMPERATURES TODAY. COLD FRONT SLIDING THROUGH MONTANA...WILL
CROSS THE AREA OVERNIGHT AS SHORTWAVE TRACKS ACROSS NORTH DAKOTA.
LIGHT WINDS EARLY SATURDAY WITH HIGH PRESSURE...AS HIGH MOVE EAST
DURING THE DAY SOUTHEAST WINDS WILL INCREASE ACROSS NORTHEAST
WYOMING/WESTERN SOUTH DAKOTA. NEXT SHORTWAVE CROSSES THE NORTHERN
PLAINS SATURDAY NIGHT/SUNDAY. MODELS INDICATING SOME VERY LIGHT
PRECIPITATION ACROSS NORTHWEST SOUTH DAKOTA SATURDAY NIGHT...THOUGH
SOUNDINGS SHOW DRY AIR IN LOW LEVELS. MAY BE A FEW SPRINKLES...HOWEVER
WILL KEEP DRY FORECAST FOR NOW.

EXTENDED...MAINLY DRY AND MILD WEATHER IS EXPECTED FOR THE FIRST
HALF OF NEXT WEEK AS AN UPPER RIDGE REMAINS OVER THE AREA BEHIND
EXITING SHORTWAVE SYSTEM. TEMPS WILL GENERALLY BE ABOVE SEASONAL
AVERAGES. NEXT CHANCE FOR PRECIPITATION LOOKS TO BE WEDNESDAY NIGHT
INTO THURSDAY AS NEXT SHORTWAVE APPROACHES. TEMPERATURES WILL COOL
TO NEAR AVERAGE LATE IN THE WEEK.

AVIATION...VFR CONDITIONS CAN BE EXPECTED THROUGH THE FORECAST
PERIOD. GUSTY WEST WINDS WILL SLOWLY SUBSIDE OVERNIGHT.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&

$$

HELGESON