Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 251031
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
331 AM MST TUE NOV 25 2014

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
ISSUED AT 254 AM MST TUE NOV 25 2014

MORNING UPPER ANALYSIS SHOWED A TROUGH OVER THE EASTERN HALF OF THE
CONUS WITH A RIDGE OFF THE WEST COAST. A SHORTWAVE TROUGH
CURRENTLY LOCATED OVER MONTANA WILL CROSS THE DAKOTAS TODAY INTO
TONIGHT. A SFC LOW WAS LOCATED OVER ALBERTA WITH DEEPENING LEE
SIDE SFC TROUGH EAST OF THE NRN ROCKIES.

MID-HIGH LEVEL WAA AND MOISTURE WILL INCREASE AHEAD OF THE SHORTWAVE
TROUGH THIS MORNING...SPREADING WIDESPREAD CLOUDS AND PRECIPITATION ACROSS
THE AREA. MAINLY SNOW IS EXPECTED THIS MORNING AS THE PRECIP MOVES
IN FROM THE NORTHWEST BUT GIVEN THE WARMING PROFILES THERE MAY BE
A MIX OF RAIN AND SNOW ACROSS MUCH OF THE PLAINS THIS AFTN. UP TO
A COUPLE OF INCHES OF SNOW IS EXPECTED TO FALL ACROSS PARTS OF
NORTHEASTERN WYOMING...BUT WITH SFC TEMPS RISING ABOVE THE
FREEZING MARK LATER THIS MORNING...SNOW ACCUMULATIONS ON THE ROADS
THERE MAY BE LIMITED. UP TO 3 INCHES OF SNOW IS EXPECTED ACROSS
THE NORTHWESTERN PARTS OF THE BLACK HILLS TODAY WITH LOCALLY
HIGHER AMOUNTS POSSIBLE OVER THE HIGHEST ELEVATIONS.

THE SFC LOW WILL DROP SOUTHEASTWARD FROM WESTERN NORTH DAKOTA AROUND
MID-DAY INTO EASTERN SOUTH DAKOTA THIS EVENING. NORTHWESTERLY WINDS
WILL BECOME VERY WINDY ACROSS NORTHWESTERN SOUTH DAKOTA THIS
AFTERNOON AS THE LOW DROPS SOUTHWARD AND TIGHTENS THE SFC PRESSURE
GRADIENT. THE ARRIVAL OF THE COLDER AIR LOOKS LIKE IT WILL BE
DELAYED UNTIL THIS EVENING BUT THEN GUSTY WINDS WILL SPREAD
SOUTHWARD ACROSS THE AREA AS THE COOLER AIR MOVES INTO THE AREA.
AT THIS TIME IT LOOKS LIKE MOST OF THE SNOW WILL BE OVER BY THE
TIME THE WIND PICKS UP OVER NORTHWESTERN SOUTH DAKOTA THIS AFTN
AND DUE TO THE WARM TEMPS BLOWING SNOW SHOULDN/T BE MUCH OF A
PROBLEM. THEREFORE HAVE DECIDED TO ISSUE A WIND ADVISORY FROM LATE
THIS AFTERNOON INTO TONIGHT. IF THE PRECIPITATION LINGERS LONGER
OR THE SNOW IS A BIT HEAVIER OVER NWRN SD WHEN THE WIND INCREASES
THEN THE WIND ADVISORY THERE MAY NEED TO BE CHANGED TO A WINTER
WEATHER ADVISORY UNTIL THE SNOW TAPERS OFF. 06 NAM SHOWS 850MB
WINDS INCREASING TO 45-50KTS BEHIND THE FRONT THIS AFT/EVE.
HOWEVER THERE ISN/T A VERY STRONG TEMPERATURE CONTRAST ALONG OR
DIRECTLY BEHIND THE FRONTAL BOUNDARY. THIS IS EXPECTED TO LIMIT
MIXING AND THE POTENTIAL MOMENTUM TRANSFER TO THE SFC SO IT LOOKS
LIKE THE WIND ADVISORY WILL BE ADEQUATE FOR THE SITUTATION.

THE PRECIPITATION WILL DIMINISH THIS EVENING ALTHOUGH FLURRIES OR
LIGHT SNOW ARE POSSIBLE THROUGH THE NIGHT AS THE COLDER AIR
CONTINUES TO FLOW INTO THE REGION. THERE IS A ANOTHER CHANCE OF
LIGHT SNOW ON WEDNESDAY AS A NE-SW ORIENTED REGION OF MID LEVEL
FRONTOGENESIS WORKS EASTWARD ACROSS THE FORECAST AREA AND RELATIVELY
WARMER AIR ALOFT OVER RIDES THE COLDER AIR AT THE SFC.

&&

.LONG TERM...THURSDAY THROUGH MONDAY
ISSUED AT 254 AM MST TUE NOV 25 2014

LOW AMPLITUDE RIDGING WILL DEVELOP THANKSGIVING DAY
ACROSS THE ROCKIES INTO THE NORTHERN PLAINS. STRONG WARM AIR
ADVECTION WILL DEVELOP WEDNESDAY NIGHT INTO THURSDAY PUSHING THE
WARM FRONT NE INTO THE CENTRAL DAKOTAS. THE RESULT WILL BE DRY AND
MUCH WARMER WEATHER FOR THANKSGIVING AND FRIDAY. CNTRL SD WILL REACH
THE 30S AS THE FRONTAL BOUNDARY GRADUALLY PUSHES THROUGH DURING THE
DAY. FARTHER WEST INTO THE WARM SECTOR...HIGHS WILL LIKELY REACH
WELL INTO THE 40S TO POSSIBLY LOWER 50S. ON FRIDAY...HIGHS WILL
REACH THE UPPER 40S TO UPPER 50S.

THE NEXT COLD FRONT WILL CROSS THE AREA SATURDAY AS A SHALLOW TROUGH
CROSSES SRN CANADA INTO MT/ND. IF THIS SOLUTION PANS OUT...TEMPS
WILL BE DROPPING THROUGH THE DAY SATURDAY INTO THE TEENS AND
20S...AND THEN SINGLE DIGITS OVERNIGHT. WELL BELOW AVERAGE TEMPS ARE
EXPECTED AGAIN SUNDAY...BUT THEN MODELS SHOW WARMER AIR ADVECTING
BACK IN EARLY NEXT WEEK POTENTIALLY RESULTING IN NEAR AVERAGE TEMPS.
AT THIS TIME IT APPEARS SOME SNOW WILL ACCOMPANY THE FRONTAL
PASSAGE/CAA SATURDAY AND SUNDAY...BUT IT APPEARS QPF WILL BE MINIMAL.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING
ISSUED AT 254 AM MST TUE NOV 25 2014

SNOW WILL REDEVELOP ACROSS THE REGION FROM THE NW TO SE
THIS MORNING BRINGING WIDESPREAD MVFR/IFR CONDITIONS. SOME LIFR
CONDITIONS EXPECTED AROUND THE NRN BLKHLS. GUSTY W/NW WINDS EXPECTED
TO DEVELOP BY THIS AFTERNOON.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM 7 PM THIS EVENING TO 5 AM MST WEDNESDAY FOR
     SDZ014-025-026-031-032-043-072-073.

     WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 1 AM MST WEDNESDAY FOR
     SDZ001-002-012-013.

WY...NONE.
&&

$$

SHORT TERM...10
LONG TERM...13
AVIATION...13





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