Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 031826
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1126 AM MST WED FEB 3 2016

.UPDATE...
ISSUED AT 1126 AM MST WED FEB 3 2016

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER SOUTHERN
MANITOBA...WITH TROF STRETCHING SOUTHWESTWARD ACROSS ND INTO
WESTERN SD. UPPER LEVEL ANALYSIS SHOWS LARGE SCALE TROF OVER THE
REGION...WITH EMBEDDED SHORTWAVE ENERGY MOVING ACROSS THE AREA.
STEEP LAPSE RATES AND LOW LEVEL MOISTURE HELPING TO PRODUCE SNOW
SHOWERS ACROSS PORTIONS OF THE AREA THIS MORNING...ESPECIALLY FROM
THE BLACK HILLS ONTO THE WESTERN SD PLAINS. SNOW SHOWERS HAVE
DECREASED IN COVERAGE AND INTENSITY LATE THIS MORNING. SKIES ARE
VARIABLY CLOUDY...WITH THE MOST CLOUDS GENERALLY ACROSS NORTHWEST
SD AND THE BLACK HILLS. TEMPS ARE IN THE 20S...WITH NORTHWESTERLY
WINDS BREEZY ACROSS NORTHWEST SD BEHIND THE SURFACE TROF.

HAVE UPDATED THE FORECAST TO MAKE MINOR ADJUSTMENTS TO POPS FOR
THIS AFTERNOON...WITH THE MAIN CHANCES ACROSS THE BLACK HILLS INTO
PORTIONS OF SOUTHWESTERN SD. ADDITIONAL LIGHT ACCUMULATIONS ARE
POSSIBLE IN A FEW AREAS...MAINLY THE NORTHERN BLACK HILLS AND
POSSIBLY ALONG THE PINE RIDGE. ACTIVITY SHOULD TAPER OFF BY
SUNSET. TEMPS WILL RISE A FEW MORE DEGREES IN MOST AREAS EARLY
THIS AFTERNOON...WITH HIGHS IN THE MID 20S TO LOWER 30S. BRISK
NORTHWEST WINDS OVER THE NORTHWEST AND WEST CENTRAL SD PLAINS
WILL ALSO GRADUALLY DECREASE TOWARD SUNSET.

&&

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
ISSUED AT 246 AM MST WED FEB 3 2016

UPPER LEVEL ANALYSIS HAS BROAD TROF ACROSS THE WESTERN CONUS WITH
RIDGE JUST MOVING ONTO THE WEST COAST. WEAK ENERGY ALONG A LOW
LEVEL FRONTAL BOUNDARY IN CYCLONIC FLOW IS PRODUCING SOME LIGHT
SNOW SHOWERS ACROSS FAR WESTERN SOUTH DAKOTA. SOME CLEARING IS
OCCURRING ACROSS FAR NORTHEAST WYOMING AND NORTHWESTERN SOUTH
DAKOTA. AT THE SURFACE...WEAK FRONTAL BOUNDARY RESIDES FROM SE
MONTANA THROUGH THE BLACK HILLS...AND INTO THE NEBRASKA PANHANDLE.
WINDS ARE LIGHT OUT OF THE WEST BEHIND THIS BOUNDARY...AND OUT OF
THE NORTH TO NORTHWEST ACROSS THE SOUTH DAKOTA PLAINS.
TEMPERATURES AT 3AM ARE IN THE TEENS TO LOWER 20S.

TODAY...CYCLONIC FLOW ALOFT COMBINED WITH THE WEAK FRONTAL
BOUNDARY WILL KEEP SOME LIGHT SNOW SHOWERS IN THE AREA...WITH
LIGHT UPSLOPE SNOWS EXPECTED ACROSS THE NORTHERN BLACK HILLS.
VERY LIGHT SNOW ACCUMULATIONS ARE LIKELY ACROSS PARTS OF THE
WESTERN SOUTH DAKOTA PLAINS THIS MORNING...WITH 1 TO 2 INCHES OF
SNOWFALL POSSIBLE OVER THE NORTHERN BLACK HILLS. BRISK NORTHWEST
WINDS WILL DEVELOP ACROSS THE NORTHWEST SD PLAINS DURING THE
MORNING AS STRONGER WINDS ALOFT MIX DOWN. TEMPS WILL REMAIN ON THE
COOL SIDE...WITH HIGHS MOSTLY IN THE MID 20S TO LOWER 30S. LIGHT
SNOW WILL FINALLY END BY THIS EVENING...WITH VARIABLY CLOUDY SKIES
EXPECTED. TEMPERATURES TONIGHT WILL MOSTLY BOTTOM OUT IN THE
TEENS...WITH SOME SINGLE DIGITS POSSIBLE IN VALLEY LOCATIONS.

THURSDAY...WESTERN RIDGE WILL CROSS THE ROCKIES AND NOSE INTO THE
NORTHERN PLAINS. MOSTLY SUNNY TO PARTLY CLOUDY SKIES ARE EXPECTED
WITH TEMPERATURES WARMING INTO THE 30S. ANOTHER WEAK SHORTWAVE
WILL SLIDE ACROSS THE NORTHERN PLAINS THURSDAY NIGHT...BRINGING
ADDITIONAL VERY LIGHT SNOW SHOWERS TO MUCH OF THE AREA. LOWS
THURSDAY NIGHT WILL FALL INTO THE TEENS.

.LONG TERM...FRIDAY THROUGH TUESDAY
ISSUED AT 246 AM MST WED FEB 3 2016

UPPER RIDGE OVER THE ROCKIES WILL MOVE INTO THE AREA FOR
FRIDAY/EARLY SATURDAY WITH THERMAL RIDGE AND WARMING TREND.
SHORTWAVE TROUGH WILL BRIEFLY BREAK DOWN RIDGE FOR SATURDAY
AFTERNOON INTO SUNDAY MORNING WITH POPS WARRANTED FOR RAIN/SNOW.
HIGHLY AMPLIFIED FLOW THEN DEVELOPS FOR SUNDAY INTO EARLY NEXT
WEEK WITH STRONG UPPER RIDGE OVER THE WEST AND DEEP TROUGH OVER
THE CWA. CWA WILL REMAIN ON THE EDGE OF BOTH FEATURES WITH A VERY
SHARP ARCTIC BOUNDARY ACROSS THE DAKOTAS OR EVEN EASTERN MT/WY.
RESULT WILL BE CHANCES FOR RAIN/SNOW AND GREAT UNCERTAINTY FOR
TEMPERATURES. GFS ENSEMBLE MOS HAS HIGHS FROM 19-64F FOR WEDNESDAY
FOR KRAP. LATEST ECMWF RUN CONTINUES TO BE WARMER FOR MOST OF THE
CWA EARLY NEXT WEEK...ALTHOUGH SUSPECT WE MIGHT SEE A DAY OR TWO
OF FZFG/TEMPERATURES IN THE 20S ON THE SD PLAINS AND 50S OVER THE
HIGHER TERRAIN AND OVER NORTHEAST WY.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z THURSDAY
ISSUED AT 1030 AM MST WED FEB 3 2016

IFR CIGS AND POSSIBLY A FEW FLURRIES WILL OCCUR OVER PARTS OF FAR
NORTHWESTERN SOUTH DAKOTA THIS AFTERNOON WITH CONDITIONS
IMPROVING TO VFR THERE DURING THE LATE AFTN OR EARLY EVE. ISOLD TO
SCT -SHSN WILL CONTINUE TO MOVE SOUTHEASTWARD ACROSS PARTS OF
WESTERN AND SOUTH CENTRAL SOUTH DAKOTA THIS AFTERNOON MVFR
CONDITIONS CAN BE EXPECTED WITH THE SNOW SHOWERS. ISOLD-SCT -SHSN
ARE ALSO EXPECTED OVER THE NRN AND CNTL BLACK HILLS TODAY WITH LCL
IFR CONDITIONS POSSIBLE WITH THE SHOWERS OVER THE HILLS.
CONDITIONS WILL IMPROVE TO VFR BY LATE AFTN/EARLY EVE.


&&

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

$$

UPDATE...26
SHORT TERM...15
LONG TERM...HELGESON
AVIATION...10


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