Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 271727
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1027 AM MST THU NOV 27 2014

.UPDATE...
ISSUED AT 938 AM MST THU NOV 27 2014

16Z SURFACE ANALYSIS HAD LOW OVER SOUTHERN AB WITH WARM FRONT INTO
SOUTHEAST WY. 2-4MB/3HR PRESSURE FALLS AHEAD OF FRONT...AND AHEAD
OF UPPER RIDGE BUILDING OVER THE ROCKIES. FRONT WILL SURGE
EASTWARD TODAY/TONIGHT BRINGING WARMER TEMPERATURES TO PORTIONS OF
THE CWA. PROBLEM IS ON THE SD PLAINS WHERE 12Z KUNR SOUNDING
SUGGESTS THE WARM AIR MAY OVERRIDE THE COLD AIR NEAR THE SURFACE
THROUGH THE DAY-TIME HOURS. THIS WILL CREATE A VERY TIGHT
TEMPERATURE GRADIENT WITH 40S OVER THE HIGHER ELEVATIONS AND 20S
ON THE PLAINS. HAVE MADE MINOR ADJUSTMENTS TO CURRENT FORECAST FOR
LATEST TRENDS.

&&

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 321 AM MST THU NOV 27 2014

UPPER LEVEL ANALYSIS HAS A TROF OVER THE MISSISSIPPI VALLEY WITH A
RIDGE OVER THE WEST COAST. FAST NORTHWEST FLOW CONTINUES OVER THE
NORTHERN PLAINS IN BETWEEN THESE TWO FEATURES...WITH 120KT JET
ACROSS THE WESTERN DAKOTAS. SKIES ARE CLOUDY WITH SOME PATCHY FOG
NEAR THE FOOTHILLS. RADAR SHOWS SOME LIGHT RETURNS /SNOW/ ACROSS
PORTIONS OF THE WESTERN SOUTH DAKOTA PLAINS.

FOR TODAY...THE WESTERN RIDGE AND WARMER AIR WILL CONTINUE TO BUILD
INTO THE NORTHERN ROCKIES AND PLAINS. THERE WILL BE A WIDE RANGE OF
TEMPERATURES ACROSS THE FORECAST AREA AS THE COLDER AIR RETREATS TO
THE EAST AND WARMER AIR MOVES IN FROM THE SOUTHWEST. OVERALL HIGHS
WILL BE TRICKY TODAY...ESPECIALLY IN THE TRANSITION ZONE CLOSE TO
THE EASTERN FOOTHILLS WHERE HIGHS COULD EASILY VARY 20 DEGREES
WITHIN A FEW MILES. OVERALL EXPECTING HIGHS TO RANGE FROM THE MID
50S IN NORTHEASTERN WYOMING TO THE MID 20S TOWARD NORTH CENTRAL
SOUTH DAKOTA. AS FAR AS PRECIPITATION GOES...A CHANCE FOR LIGHT SNOW
THIS MORNING IS POSSIBLE OVER FAR NORTHWESTERN SOUTH DAKOTA WITH A
CHANCE FOR FREEZING RAIN IN THIS SAME AREA THIS AFTERNOON AS WARMER
AIR JUST ABOVE THE SURFACE ADVECTS INTO THAT REGION. ALSO COULD SEE
SOME FLURRIES IN SOUTH CENTRAL SOUTH DAKOTA THROUGH EARLY THIS
MORNING.

FOR TONIGHT...PRECIPITATION WILL LIFT NORTH AND EAST OF THE AREA.
TEMPERATURES WILL BE IN THE MID 20S TO UPPER 30S WITH NEAR STEADY
TEMPERATURES OVER NORTHWESTERN SOUTH DAKOTA.

FOR FRIDAY AND FRIDAY NIGHT...UPPER FLOW BECOMES MORE ZONAL WITH WARM AIR
IN PLACE OVER THE FORECAST AREA. 850MB TEMPS BETWEEN +10 AND +15
SHOULD TRANSLATE INTO SURFACE HIGHS IN THE MID 40S TO UPPER 50S.
WITH WESTERLY FLOW...EXPECT GUSTY WEST/SOUTHWEST WINDS ESPECIALLY
OVER NORTHEASTERN WYOMING. WITH GUSTY WINDS CONTINUING OVERNIGHT...
TEMPERATURES WILL REMAIN FAIRLY MILD WITH LOWS ONLY IN THE MID 20S
TO MID 30S.

&&

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 321 AM MST THU NOV 27 2014

THE NEXT TROUGH WILL CROSS THE PACIFIC NORTHWEST SATURDAY...
BRINGING A SURGE OF COLD AIR TO THE NORTHERN PLAINS. A STRONG COLD
FRONT WILL CROSS THE CWA SATURDAY NIGHT. MAX TEMPS WILL CONTINUE
TO BE TRICKY FOR SATURDAY SINCE IT WILL LARGELY DEPEND ON THE
TIMING OF THE FRONTAL PASSAGE. SOME LIGHT SNOW IS POSSIBLE SAT
NIGHT INTO SUNDAY...BUT JUST LIGHT 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 FRIDAY)
ISSUED AT 1021 AM MST THU NOV 27 2014

WDSPRD MVFR/IFR CONDITIONS EXPECTED TO PERSIST TODAY ACROSS MUCH
OF THE SD PLAINS NORTH OF INTERSTATE 90...WITH SPOTTY AREAS OF
-SN/FZRA ACROSS FAR NORTHWEST SD THROUGH EARLY EVENING. LIFR
CIGS/VSBY WITH FG WILL AFFECT THE NRN AND ERN FOOTHILLS AREAS OF
THE BLKHLS THROUGH MID AFTERNOON BEFORE SLOWLY DISSIPATING. ALL
PCPN AND LOW STRATUS WILL SHIFT EAST OF THE REGION BY LATE THIS
EVENING. ELSEWHERE VFR CONDITIONS EXPECTED THROUGH FRI MORNING.

&&

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

$$

UPDATE...HELGESON
SHORT TERM...MLS
LONG TERM...13
AVIATION...15





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