Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 221538
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
838 AM MST SAT NOV 22 2014

.UPDATE...
ISSUED AT 835 AM MST SAT NOV 22 2014

POTENT NW CONUS UPPER TROUGH CONTINUES TO ADVECT EAST INTO THE
NORTHERN PLAINS. TIMING OF UVM LOOKS OT BE A LITTLE EARLIER THAN
PREVIOUS GUIDANCE SUGGESTED. GIVEN UPSTREAM OB TRENDS...WENT AHEAD
AND INCREASED POPS THIS AFTERNOON FAR NW. OTHERWISE...WENT AHEAD
AND ISSUED A HIGH WIND WATCH FOR NW SD SUNDAY GIVEN
MOMENTUM/MIXING PROGS. WIND GUSTS TO AROUND 60 LOOK LIKELY ACROSS
FAR NW SD...AND POSSIBLE AS FAR SOUTH AS RAPID CITY.

&&

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
ISSUED AT 301 AM MST SAT NOV 22 2014

AN ACTIVE WESTERLY FLOW ALOFT DOMINATES THE LARGE
SCALE FOR THE NORTHERN U.S. THIS MORNING.  WEAK IMPULSES EMBEDDED IN
THE FLOW ARE MOVING INTO THE NORTHERN PLAINS PRODUCING SOME VERY
LIGHT PRECIPITATION EAST OF THE CONTDVD...BUT NO SIGNIFICANT FRONTAL
BOUNDARIES ARE IN THE ANALYSIS ACROSS THE NORTHERN PLAINS OR
NORTHERN ROCKIES. EARLY MORNING TEMPERATURES ACROSS THE NORTHERN
PLAINS ARE SEASONABLY MILD BUT WARM CONSIDERABLY TO THE WEST IN THE
NORTHERN INTERMOUNTAIN REGION. A VIGOROUS FAST MOVING PACIFIC SHORT
WAVE WAS MOVING ONSHORE AT 09Z. A SPLIT FLOW OVER THE SOUTHERN GREAT
BASIN HAS PRETTY MUCH CUT OFF THE HIGH AMPLITUDE TROUGH OVER THE
SOUTHWESTERN U.S. AND NORTHERN MEXICO WHICH IS MAKING SLOW PROGRESS
EASTWARD.

TODAY...ANOTHER DAY OF ABOVE NORMAL TEMPERATURES IS IN STORE FOR
NORTHEAST WYOMING AND WESTERN SOUTH DAKOTA TODAY.  THE APPROACHING
WEATHER SYSTEM WILL PRODUCE INCREASING HIGH CLOUDS FROM MID MORNING
ONWARD...BUT MAXIMUM TEMPERATURES ARE STILL EXPECTED TO BE AT LEAST
A COUPLE DEGREES HIGHER THAN YESTERDAY.  A FEW LIGHT RAIN SHOWERS
ARE POSSIBLE OVER NORTHEAST WYOMING AND THE BLKHLS REGION LATE THIS
AFTERNOON WITH THE DCVA FROM THE APPROACHING SYSTEM.

TONIGHT...THE MAIN PRECIPITATION EVENT WILL BEGIN DURING THE LATE
EVENING HOURS AS THE FAST MOVING COLD FRONT MOVES INTO THE PLAINS.
THE PRECIP WILL FALL AS RAIN INITIALLY THEN BECOME MIXED WITH SNOW
AFTER 06Z AND BE ALL SNOW BY EARLY SUNDAY MORNING.  DEPENDING ON
WHEN THE SWITCHOVER ACTUALLY OCCURS THE HIGHER ELEVATIONS OF THE
BLKHLS AND NORTHEAST WYOMING COULD SEE FROM 4 TO 8 INCHES OF NEW
SNOW BY EARLY SUNDAY.

SUNDAY...THE PACIFIC TROUGH IS FORECAST TO BEGIN SPLITTING AND
SLOWING DOWN AS IT MOVES INTO THE PLAINS EARLY SUNDAY.  THIS
EVOLUTION WILL CREATE A PERIOD OF STRONG NORTHERLY SURFACE FLOW
...ESPECIALLY ACROSS WESTERN SOUTH DAKOTA...BY MIDDAY SUNDAY. THE
WINDS AND COLDER TEMPERATURES WILL BECOME THE MAIN WEATHER STORY ON
SUNDAY AS DYNAMICS TO SUPPORT THE LIGHT SNOW WILL GRADUALLY FADE.
WIND SPEEDS MEETING HIGH WIND CRITERIA ARE A POSSIBILITY EARLY
SUNDAY AFTERNOON.

SUNDAY NIGHT...LIGHT SNOW SHOWERS WILL CONTINUE THROUGH THE
OVERNIGHT HOURS BEHIND THE MAIN WEATHER SYSTEM WITH LITTLE
ACCUMULATION. MID LEVEL COLD ADVECTION AND A FEW WEAK EMBEDDED
IMPULSES WILL CONTINUE ALL NIGHT.

&&

.LONG TERM...MONDAY THROUGH FRIDAY
ISSUED AT 301 AM MST SAT NOV 22 2014

AN ACTIVE PATTERN ASSOCIATED WITH DEEP CYCLONIC FLOW
ALOFT WILL CONTINUE ACROSS THE NORTH CENTRAL CONUS THROUGH EARLY
NEXT WEEK. SEVERAL WEAK DISTURBANCES WITHIN THE NORTHWEST FLOW WILL
BRING CLOUDS AND CHANCES FOR SNOW AT TIMES THROUGH TUESDAY. A COLD
FRONT WILL CROSS THE DAKOTAS WEDNESDAY...BRINGING COOLER TEMPS
ACROSS MOST AREAS. SNOW IS ALSO EXPECTED TO DEVELOP ALONG THE
BAROCLINIC ZONE...ESPECIALLY ACROSS NE WY AND PORTIONS OF FAR WRN
SD.

THERE IS STILL UNCERTAINTY TOWARD THE LATTER PART OF NEXT
WEEK...WITH LONGER RANGE MODELS CONTINUING TO FIGURE OUT WHAT TYPE
OF AIRMASS WILL BE OVER THE AREA. MODELS HAVE BEEN SHOWING WARMER
AIR ADVECTING IN WITH THE FRONTAL BOUNDARY SLIDING EAST OF THE
CWA...BUT THE 00Z GFS HAS TRENDED BACK TO A COLDER SOLUTION WHILE
THE 00Z ECM HAS TRENDED WARMER. WILL STICK WITH TEMPS IN THE MIDDLE
OF ALL SOLUTIONS.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING
ISSUED AT 301 AM MST SAT NOV 22 2014

VFR CONDITIONS EXPECTED THROUGH THIS AFTERNOON. BREEZY
SOUTHWEST WILL CONTINUE ACROSS NORTHEAST WY/HIGHER ELEVATIONS OF THE
BLACK HILLS TODAY. A COLD FRONT WILL CROSS THE AREA TONIGHT...WITH
GUSTY NW WINDS DEVELOPING BEHIND THE FRONT. CHANCES FOR SHRA ARE
EXPECTED THIS AFTN AND TONIGHT...CHANGING TO SHSN OVERNIGHT.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...HIGH WIND WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR
     SDZ001-002-012-013-025-026-031-072-073.

WY...NONE.
&&

$$

UPDATE...JC
SHORT TERM...CARPENTER
LONG TERM...13
AVIATION...13





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