Area Forecast Discussion
Issued by NWS Rapid City, SD

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638
FXUS63 KUNR 111655
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
955 AM MST THU FEB 11 2016

.UPDATE...
ISSUED AT 946 AM MST THU FEB 11 2016

FAST NORTHWEST FLOW ALOFT CONTINUES ACROSS THE NORTHERN PLAINS.
STATIONERY SURFACE BOUNDARY IS STARTING TO SHIFT EAST THIS MORNING
WITH CLOUDS...FOG...AND COOL POOL OF AIR RETREATING EAST ACROSS
THE SOUTH DAKOTA PLAINS. THE TEMPERATURE HAS RISEN 25 DEGREES IN
THE PAST 30 MINUTES IN RAPID CITY...AND WINDS HAVE INCREASED OUT
OF THE NORTHWEST TO 20-25 MPH. FURTHER NORTH AND EAST...PERSISTENT
BAND OF SNOW ACROSS FAR NORTHERN SOUTH DAKOTA HAS PRODUCED AROUND
AN INCH OF SNOW IN THE LEMMON AREA...WITH ANOTHER INCH EXPECTED.
MOST OF THE CWA WILL SEE MILD TEMPS AS THE BOUNDARY SHIFTS
EAST...BUT ANOTHER SHORTWAVE WILL DROP OUT OF CANADA...AND PUSH
THE BOUNDARY/CLOUDS/FOG/LIGHT SNOW/COOLER AIR BACK INTO THE BLACK
HILLS REGION TONIGHT.

&&

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 231 AM MST THU FEB 11 2016

STRONG NORTHWEST FLOW PERSISTS ACROSS THE CENTRAL STATES...WITH A
WEAK UPPER WAVE PUSHING SOME STRATUS INTO THE REGION. SURFACE
BOUNDARY HAS SHIFTED WESTWARD...AND LOW CLOUDS HAVE FORMED ACROSS
MUCH OF SD. RADAR SHOWS ECHOES ACROSS EASTERN MT/WESTERN ND...WITH
SOME DEVELOPMENT OVER NORTHWESTERN SD. WINDS ARE LIGHT AND
SOUTHERLY...AND TEMPS ARE IN THE 20S TO LOW 30S.

UPPER WAVE WILL CONTINUE PUSHING INTO THE REGION...PRODUCING SOME
LIGHT RAIN/SNOW ALONG THE BOUNDARY ACROSS NORTHWESTERN INTO CENTRAL
SD. NORTHWEST WINDS WILL INCREASE BEHIND THE WEAK SURFACE LOW
CROSSING THE AREA...REACHING 15-25 KTS ACROSS THE USUAL WINDY SPOTS
OF NORTHWEST SD AND JUST EAST OF THE BLACK HILLS. TEMPERATURES WILL
RISE INTO THE 40S AND LOWER 50S TO THE WEST OF THE BOUNDARY...WITH
30S ACROSS CENTRAL SD AND EASTWARD.

TONIGHT...COLD AIR WILL AGAIN MOVE SOUTH AND WESTWARD AS HIGH
PRESSURE BEGINS TO SINK INTO THE NORTHERN PLAINS. WITH SOME LIGHT
UPSLOPING WINDS DEVELOPING ON BOTH THE SD PLAINS AND NORTHEASTERN
WY...FOG MAY DEVELOP OVERNIGHT. COULD SEE A LITTLE LIGHT PRECIP OVER
THE SD PLAINS...BUT MOIST PROFILES THROUGH ABOUT 5KFT INDICATE TYPE
SHOULD BE RAIN/SNOW RATHER THAN FREEZING RAIN. LOWS WILL BE IN THE
20S.

COLD AIRMASS WILL LINGER OVER MUCH OF THE CWA ON FRIDAY. HIGHS WILL
RANGE FROM THE MID 20S ACROSS CENTRAL SD...TO THE 30S ACROSS FAR
WESTERN SD...WITH LOW 40S IN NORTHEASTERN WY. MAY BE SOME LIGHT
PRECIP AROUND THE BLACK HILLS INTO NORTHEASTERN WY. BY FRIDAY
NIGHT...ANOTHER BAND OF PRECIP IS EXPECTED TO DEVELOP OVER THE
BAROCLINIC ZONE. TYPE SHOULD BE SNOW IN THE EVENING...BUT THEN AN
INTRUSION OF WARM AIR ALOFT COULD MEAN PRECIP CHANGES TO FREEZING
DRIZZLE/RAIN AFTER MIDNIGHT.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 231 AM MST THU FEB 11 2016

THE SFC FRONT AND ASSOCIATED BAROCLINIC ZONE WILL SHIFT
BACK EASTWARD ON SATURDAY AND WILL MOVE OUT TO THE EAST OF THE
FORECAST AREA ON SUNDAY. HIGHS ON SATURDAY WILL BE IN THE MID 40S TO
AROUND 50 TO THE WEST OF THE BOUNDARY OVER NORTHEASTERN
WYOMING...THE BLACK HILLS AND SOUTHWESTERN SOUTH DAKOTA. EAST OF THE
BOUNDARY...HIGHS WILL ONLY REACH THE UPPER 20S TO MID 30S. ON
SUNDAY...HIGHS ON THE PLAINS ARE EXPECTED TO BE IN THE 40S. WARMER
THAN AVERAGE TEMPERATURES WILL CONTINUE THROUGH THE REST OF THE WEEK.

ACTIVE NORTHWEST FLOW ALOFT WILL PERSIST OVER THE FORECAST AREA
THROUGH MOST OF THE EXTENDED FORECAST PERIOD WITH A PERSISTENT UPPER
TROUGH OVER THE WESTERN CONUS. THE BEST CHANCE OF PRECIPITATION WILL
OCCUR ON SATURDAY AND SATURDAY NIGHT AS AN UPPER TROUGH CROSSES THE
NORTHERN PLAINS AND INTERACTS WITH THE SFC FRONT MOVING EASTWARD
ACROSS THE FORECAST AREA. MODEL SOUNDINGS INDICATE THAT THE
PRECIPITATION TYPE SHOULD BE MOSTLY SNOW BUT SOME LIGHT FREEZING
RAIN CLOUD OCCUR NEAR THE FRONT EARLY SATURDAY WITH LIGHT RAIN
POSSIBLE WEST OF THE BOUNDARY DURING THE DAY. DURING THE REST OF THE
PERIOD THE MAIN CHANCES FOR LIGHT PCPN WILL BE OVER PARTS OF NERN
WY...THE NRN BLKHLS AND NWRN SD. GUSTY NORTHWESTERLY WINDS ARE ALSO
POSSIBLE AS THESE DISTURBANCES PASS THROUGH. THERE IS SOME POTENTIAL
FOR STRONG WINDS EARLY NEXT WEEK...ESPECIALLY OVER NORTHWEST SD...IF
TEMPS WARM SUFFICIENTLY ON MONDAY AND TUESDAY TO ALLOW FOR DEEPER
BOUNDARY LAYER MIXING.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING
ISSUED AT 231 AM MST THU FEB 11 2016

IFR ST/FG DECK ON THE WESTERN SD PLAINS WILL PUSH
WESTWARD INTO THE EASTERN SLOPES OF THE BLACK HILLS THROUGH THIS
MORNING WITH VFR CONDITIONS OVER MUCH OF NE WY AND THE HIGHER
ELEVATIONS OF THE BLACK HILLS. PATCHY -FZDZ MAY OCCUR ESP ALONG THE
ERN FOOTHILLS. A FAST MOVING DISTURBANCE WILL BRING MIXED
PRECIPITATION TO NORTHWEST AND CENTRAL SOUTH DAKOTA THIS
MORNING...BUT WILL DRIVE A BOUNDARY THROUGH THE AREA RESULTING IN
THE ST/FG MIXING OUT/PUSHING EAST BY MIDDAY WITH WITH GUSTY
NORTHWEST WINDS DEVELOPING. THE ST/FG WILL THEN AGAIN MOVE BACK TO
THE WEST TONIGHT AS THE BOUNDARY LAYER COOLS AND A BIGGER PUSH OF
COLDER AIR MOVES IN.


&&

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

$$

UPDATE...15
SHORT TERM...POJORLIE
LONG TERM...10
AVIATION...10



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