Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 050327
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
827 PM MST THU FEB 4 2016

.UPDATE...
ISSUED AT 818 PM MST THU FEB 4 2016

CURRENT SURFACE MAP SHOWS LOW ACROSS EASTERN MONTANA...WITH TROF
EXTENDING INTO EASTERN WYOMING. COMPACT SHORTWAVE DROPPING THROUGH
EASTERN MONTANA...WITH SNOW SHOWERS MOVING INTO SOUTHEAST
MONTANA. SHORTWAVE CROSSES WESTERN SOUTH DAKOTA OVERNIGHT...AND
MOVES EAST OF THE AREA EARLY FRIDAY MORNING. STEEP MID LEVEL LAPSE
RATES WITH SHORT WINDOW OF FAVORABLE FORCING SHOULD BRING SNOW
SHOWERS INTO NORTHEAST WYOMING/FAR WESTERN SOUTH DAKOTA TONIGHT.
0-2KM RH/WIND AND LOW LEVEL LAPSE RATES GIVE UPSLOPE AREAS OF
NORTHERN BLACK HILLS/BEAR LODGE MOUNTAINS 4-6 HOUR PERIOD OF
UPSLOPE POTENTIAL LATER TONIGHT/EARLY FRIDAY. MADE SOME
ADJUSTMENT TO POPS/QPF/SNOW FOR BETTER CHANCE OF UPSLOPE SNOWS.

&&

.SHORT TERM...THIS EVENING THROUGH FRIDAY NIGHT
ISSUED AT 300 PM MST THU FEB 4 2016

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER SOUTHWEST
SK...WITH FRONTAL BOUNDARY TO THE NORTH AND EAST OF THE AREA AND A
TROF STRETCHING SOUTHWARD INTO EASTERN WY. UPPER LEVEL ANALYSIS
SHOWS LARGE SCALE TROF TO THE EAST OF THE REGION...WITH A RIDGE
ALONG THE WEST COAST. NORTHWESTERLY FLOW REMAINS ACROSS THE
ROCKIES AND HIGH PLAINS. SHORTWAVE ENERGY WITHIN THE FLOW IS
MOVING ACROSS CENTRAL MT AND WESTERN WY. REGIONAL RADARS SHOW SOME
LIGHT RETURNS ACROSS PORTIONS OF EASTERN MT...EASTERN WY...AND NOW
THE BLACK HILLS...BUT LITTLE IN THE WAY OF PCPN IS REACHING THE
GROUND AT THIS POINT. CLOUDS HAVE INCREASED ACROSS NORTHEAST WY
AND WESTERN SD LATE THIS MORNING AND AFTERNOON. TEMPS ARE IN THE
UPPER 20S TO MID 30S WITH LIGHT WEST OR SOUTHWEST WINDS IN MOST
AREAS...THOUGH A BIT BREEZY OVER PORTIONS OF THE BLACK HILLS.

SHORTWAVE WILL MOVE ACROSS THE REGION TONIGHT AND EARLY FRIDAY...
BRINGING SOME SNOW SHOWERS TO THE AREA. THE BEST CHANCES FOR SNOW
WILL BE OVER THE BEAR LODGE MTS AND NORTHERN BLACK HILLS WHERE AN
INCH OR TWO OF ACCUMULATION IS LIKELY...ESPECIALLY NORTHWEST FACING
SLOPES AS WINDS INCREASE OVERNIGHT AND SOME UPSLOPE ENHANCED
SNOWFALL DEVELOPS. ELSEWHERE...CHANCES FOR MEASURABLE PCPN SHOULD
REMAIN LOW...WITH 20 TO 30 PERCENT POPS MOST EVERYWHERE ELSE.
LINGERING SNOW SHOWERS SHOULD END ACROSS THE AREA BY LATE MORNING AS
THE SHORTWAVE TRACKS SOUTHEAST OF THE AREA.

SURFACE LOW WILL TRACK ACROSS NORTHEAST MT AND ND TONIGHT AND DRAG
THE TROF THROUGH THE AREA. BREEZY NORTHWEST WINDS CAN BE EXPECTED
LATE TONIGHT AND FRIDAY...ESPECIALLY OVER NORTHWEST SD. THE TROF
WILL HELP TO MIX SOME MILDER AIR ALOFT DOWN TO THE SURFACE ON
FRIDAY...WITH HIGHS MOSTLY IN THE MID 30S TO LOWER 40S. SKIES WILL
BE MOSTLY CLEAR FRIDAY NIGHT AS WINDS TURN BACK TO THE WEST AND
SOUTHWEST BEHIND THE SYSTEM. THIS WILL HELP TO KEEP TEMPS ON THE
MILDER SIDE OVERNIGHT...WITH LOWS MOSTLY IN THE LOW TO MID 20S.
BRISK SOUTHWEST WINDS CAN BE EXPECTED ACROSS MUCH OF NORTHEAST WY
AND INTO FAVORED AREAS OF THE BLACK HILLS OVERNIGHT.

.LONG TERM...SATURDAY THROUGH THURSDAY
ISSUED AT 300 PM MST THU FEB 4 2016

FAST ACTIVE NW FLOW WILL DOMINATE THE WEATHER FOR MUCH
OF THE PERIOD...SUPPORTING PERIODIC IMPULSES INTO THE NORTHERN
PLAINS. FORECAST MODELS DO SUGGEST MASSIVE RIDGING OVER WESTERN NOAM
EARLY NEXT WEEK AS A DEEP TROUGH DIGS INTO THE EASTERN PAC.
HOWEVER...ACTIVE RIDGE TOPPING FLOW WILL LIKELY PERSIST GIVEN THE SE
BIAS TO THE ARCTIC COLD BUBBLE OVER INTERIOR CANADA...SUPPORTING
CLIPPERS INTO THE MIDWEST. THIS WILL LIKELY LEAVE THE REGION ON THE
EDGE OF FAST FLOW ALOFT...WITH SOME INFLUENCE FROM EACH PASSING
IMPULSE. SEMI-DRY NW FLOW WILL SUPPORT LOW PRECIP CHANCES IN THE
PERIOD OUTSIDE OF THE NORTHERN BLACK HILLS...WHERE TERRAIN FORCING
WILL BE IN PLACE. PERHAPS THE BIGGEST INFLUENCE FROM THIS PATTERN
WILL BE WINDY CONDS FOR MUCH OF THE PERIOD...ESP SUN. EXCELLENT
SETUP FOR HIGH WINDS ACROSS THE FA SUNDAY AS STAUNCH PRESSURE RISES
IN A CAA REGIME WITH LINKED FAST LL FLOW WILL BE IN PLACE. NAM BUFR
PROGS ARE SUPPORTING 65-70 KNOTS AROUND H7. EVEN IF ONLY MODEST
MIXING ENSUES SUN...WINDS OF 30-40 MPH WITH GUSTS ABOVE 60 LOOK
INCREASINGLY MORE LIKELY FOR MUCH OF THE NE PART OF THE FA.
STRONG FLOW ALSO LOOKS TO MIX DOWN INTO THE NORTHERN BH WHICH
WOULD BE THE CASE GIVEN STEEP LL LAPSE RATES. HAVE BUMPED WINDS UP
FOR THIS. OTHERWISE...AFTER MILD CONDS FRI AND SOMEWHAT
SAT...COOLER CONDS CAN BE EXPECTED SUN-MON...BEFORE MILD CONDS
RETURN AGAIN BY MID NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 818 PM MST THU FEB 4 2016

SNOW SHOWERS EXPECTED TO MOVE THROUGH NORTHEAST WYOMING/FAR
WESTERN SOUTH DAKOTA TONIGHT...WITH SOME SNOW SHOWERS LINGERING
ACROSS THE BLACK HILLS FRIDAY MORNING. IFR CIGS/LIFR VSBY WITH THE
HEAVIER SNOW SHOWERS.

&&

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

$$

UPDATE...7
SHORT TERM...26
LONG TERM...JC
AVIATION...7


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