Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 262111
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
211 PM MST WED NOV 26 2014

.SHORT TERM...THIS EVENING THROUGH THURSDAY NIGHT
ISSUED AT 153 PM MST WED NOV 26 2014

UPPER LEVEL ANALYSIS HAS A TROF OVER THE UPPER MIDWEST WITH A
RIDGE OVER THE FAR SW CONUS. FAST NORTHWEST FLOW CONTINUES OVER
THE NORTHERN PLAINS IN BETWEEN THESE TWO FEATURES...WITH 150KT
JET ACROSS THE WESTERN DAKOTAS. SKIES ARE CLOUDY WITH ON AND OFF
LIGHT SNOW ACROSS MUCH OF THE FORECAST AREA. AT THE
SURFACE...ARCTIC HIGH IS LOCATED ACROSS SOUTHERN CANADA WITH WEAK
LOW/TROF ACROSS CENTRAL WYOMING. TEMPERATURES ARE IN THE 20S TO
LOWER 30S WITH GENERALLY LIGHT WINDS.

TONIGHT...NW-SE ORIENTED JET/BAROCLINIC ZONE OVER THE WESTERN
DAKOTAS WILL GRADUALLY MOVE NORTHEASTWARD OVERNIGHT. LIGHT SNOW OR
FLURRIES OVER NORTHEASTERN WYOMING AND PARTS OF WESTERN SOUTH
DAKOTA WILL CONTINUE...WITH THE PRECIPITATION SPREADING
NORTHEASTWARD TONIGHT AS 500MB HEIGHTS CONTINUE TO RISE AND LOW TO
MID LEVEL WARM ADVECTION INTENSIFIES. SREF PTYPE PROBABILITIES
AND NAM VERTICAL PROFILES SUPPORT A CHANCE OF SNOW WITH A SLIGHT
CHANCE OF LIGHT FZRA/FZDZ OVER PARTS OF NORTHEASTERN WY AND
NORTHWESTERN SD LATER TONIGHT INTO EARLY THURSDAY MORNING. LOW
TEMPERATURES WILL RANGE FROM THE TEENS ACROSS THE SOUTH DAKOTA
PLAINS...TO THE UPPER 20S ACROSS NORTHEAST WYOMING.

ON THURSDAY...WESTERN RIDGE AND WARMER AIR WILL CONTINUE TO BUILD
INTO THE NORTHERN ROCKIES AND PLAINS. THERE WILL BE A WIDE RANGE
OF TEMPERATURES ON THURSDAY AS THE COLDER AIR RETREATS TO THE EAST
AND WARMER AIR MOVES IN FROM THE SOUTHWEST. HIGHS ARE EXPECTED TO
RANGE FROM AROUND 30 DEGREES TOWARD NORTH CENTRAL SOUTH DAKOTA TO
AROUND 50 DEGREES OVER PARTS OF NORTHEAST WYOMING AND SOUTHWEST
SOUTH DAKOTA. THERE WILL BE A CONTINUED CHANCE OF LIGHT SNOW AND
LIGHT FREEZING DRIZZLE ACROSS FAR NORTHWEST SOUTH DAKOTA THROUGH
THE AFTERNOON. PRECIP WILL FINALLY LIFT NORTH AND EAST OF THE AREA
THURSDAY NIGHT...WITH LOW TEMPERATURES FALLING INTO THE 20S TO MID
30S.

&&

.LONG TERM...FRIDAY THROUGH WEDNESDAY
ISSUED AT 153 PM MST WED NOV 26 2014

UPPER FLOW WILL BECOME MORE ZONAL FOR THE END OF THE
WEEK AS WEAK RIDGING BREAKS DOWN AHEAD OF THE NEXT PACIFIC TROUGH.
WARMER AIRMASS OVER THE REGION FRIDAY WILL BRING TEMPS WELL ABOVE
SEASONAL AVERAGES.

THE NEXT TROUGH WILL CROSS THE PACIFIC NORTHWEST SATURDAY...BRINGING
A SURGE OF COLD AIR TO THE NORTHERN PLAINS. BOTH THE GFS AND ECMWF
HAVE SLOWED DOWN THE COLD FRONTAL PASSAGE FROM PREVIOUS RUNS...NOW
HAVING IT PASS THROUGH THE CWA SATURDAY NIGHT. ECMWF IS STILL
SLIGHTLY FASTER THAN THE GFS. HAVE INCREASED TEMPS SOME MORE TO
ACCOUNT FOR GFS...BUT CONFIDENCE IS LOW AT THIS TIME...AS BOTH THE
ECMWF AND GFS ENSEMBLES HAVE A 30-40 DEGREE SPREAD FOR HIGH TEMPS
SATURDAY. SOME LIGHT SNOW IS POSSIBLE SAT NIGHT INTO POSSIBLY
SUNDAY...BUT MINIMAL QPF IS EXPECTED.

SUNDAY LOOKS COLD...WITH HIGHS ONLY IN THE TEENS. MODELS SUGGEST
MAINLY DRY CONDITIONS WITH MODERATING TEMPERATURES EARLY NEXT WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z THURSDAY
ISSUED AT 153 PM MST WED NOV 26 2014

SNOW WILL CONTINUE ACROSS MUCH OF THE AREA THROUGH
TONIGHT...BRINGING WIDESPREAD MVFR/IFR CONDITIONS. SOME LIFR
CONDITIONS EXPECTED NEAR THE BLKHLS AREA.

&&

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

$$

SHORT TERM...15
LONG TERM...POJORLIE
AVIATION...POJORLIE






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