FXUS63 KUNR 061000
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
300 AM MST SUN DEC 6 2009

.DISCUSSION...CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER 
SOUTHERN PORTIONS OF THE HIGH PLAINS...WITH COLD FRONT WELL SOUTH OF 
OUR REGION. MAIN SURGE OF ARCTIC AIR IS MOVING INTO THE AREA 
NOW...WITH TEMPS RANGING FROM SLIGHTLY ABOVE ZERO ACROSS FAR 
NORTHWESTERN SD...TO THE UPPER TEENS OVER FAR SOUTHERN SD. UPPER 
LEVEL ANALYSIS HAS LOW CENTERED OVER NORTHERN UT...WITH 
SOUTHWESTERLY FLOW IN PLACE ACROSS THE CENTRAL ROCKIES AND INTO THE 
CENTRAL PLAINS. SHORTWAVE NOTED ON WATER VAPOR MOVING ACROSS 
SOUTHEASTERN WY.  SKIES ARE MOSTLY CLOUDY IN GENERAL...WITH SOME 
BREAKS ACROSS THE AREA. LOCAL RADAR SHOWING SOME AREAS OF LIGHT SNOW 
ACROSS SOUTHWESTERN SD. REGIONAL RADARS SHOWING MAIN ACTIVITY ACROSS 
CENTRAL AND SOUTHEASTERN WY INTO WESTERN NEB.  
 
UNSETTLED AND VERY COLD WX CAN BE EXPECTED THROUGH THE EARLY PART OF 
THIS WEEK AS WESTERN CONUS TROF REMAINS IN PLACE AND SERIES OF 
DISTURBANCES ROTATE EASTWARD INTO THE CENTRAL PLAINS. DAILY CHANCES 
FOR SNOW WILL CONTINUE...WITH THE BEST CHANCES BEING OVER THE 
SOUTHERN CWA. ACCUMULATING SNOWS ARE EXPECTED TODAY INTO THIS 
EVENING FOR SOUTHERN SD AND NORTHEASTERN WY...WITH ANOTHER SHOT OF 
ACCUMULATING SNOW LIKELY LATE MONDAY INTO TUESDAY ACROSS BASICALLY 
THE SAME AREAS. 

FOR TODAY...BITTER COLD AIR WILL BE IN PLACE...WITH TEMPS NOT 
BUDGING A WHOLE LOT. HIGHS WILL ONLY BE IN THE 5 TO 15 DEGREE RANGE. 
NORTH-NORTHEAST WINDS IN THE 10 TO 15 MPH RANGE...HIGHER IN THE RAP 
AREA...WILL RESULT IN BELOW ZERO WIND CHILLS. LIGHT SNOW WILL EXPAND 
ACROSS SOUTHERN PORTIONS OF NORTHEASTERN WY AND SOUTHERN SD THIS 
MORNING AS WAVE APRROACHES. WILL LIKELY SEE A COUPLE OF INCHES OR SO 
OF ACCUMULATION ACROSS PARTS OF SOUTHERN SD...ESPECIALLY ACROSS FAR 
SOUTHWESTERN SD TOWARD THE NEB BORDER AND OVER PORTIONS OF THE 
BLACK HILLS. SNOW SHOULD TAPER OFF AND DISSIPATE TONIGHT AS 
WAVE EXITS. LOWS WILL DROP BELOW ZERO IN MANY LOCATIONS...WITH WIND 
CHILLS APPROACHING 20 BELOW ZERO AT TIMES. 

WILL GENERALLY SEE A BREAK IN SNOW CHANCES FROM LATE TONIGHT THROUGH 
MONDAY MORNING AS ONE WAVE EXITS AND ANOTHER ONE APPROACHES. UPPER 
LOW ACROSS THE WEST WILL EJECT EASTWARD INTO THE CENTRAL ROCKIES AND 
CENTRAL AND SOUTHERN PLAINS MONDAY NIGHT AND TUESDAY. SURFACE LOW 
WILL DEVELOP AND MOVE ACROSS THE FOUR CORNERS AREA AND INTO THE 
SOUTHERN PLAINS. OUR AREA WILL BE ON THE NORTHERN FRINGES OF THE 
STORM...BUT A DECENT WAVE WILL CROSS THE AREA MONDAY NIGHT INTO 
TUESDAY AHEAD OF THE UPPER TROF. THIS SHOULD PRODUCE PLENTY OF LIFT 
AND SQUEEZE OUT AVAILABLE MOISTURE ACROSS THE AREA...ESPECIALLY 
SOUTHERN PORTIONS OF THE CWA. LOOKS LIKE A DECENT OVERRUNNING PCPN 
EVENT WITH THE POTENTIAL FOR A FEW INCHES OF SNOW FROM I-90 
SOUTHWARD. TRACK OF THE LOW AND SUBSEQUENT WAVE WILL BE THE 
DETERMINING FACTOR AND IS STILL RATHER UNCERTAIN...BUT BETTER 
CHANCES FOR THE HEAVIER SNOWFALL WILL LIKELY BE ACROSS SOUTHERN SD 
AGAIN. BITTER COLD AIR WILL REMAIN IN PLACE THROUGH AT LEAST TUESDAY 
AND LIKELY INTO THE MIDDLE PART OF THE WEEK...BEFORE A GRADUAL 
WARMUP.     

EXTENDED...COLD NW FLOW ALOFT WILL CONT ACRS NRN PLAINS FOR WED AND 
THURS BEFORE BECOMING MORE ZONAL ON FRI/SAT. TEMPS WILL REMAIN WELL 
BELOW NORMAL WED/THUR BEFORE WARMING TO NEAR NORMAL FOR FRIDAY AND 
SATURDAY. WX SHOULD REMAIN DRY THRU THE PERIOD.

&&

.AVIATION...MVFR/IFR CIGS CAN BE EXPECTED THRU FCST PERIOD OVER NERN
WY/BLACK HILLS. ACRS PLAINS OF WRN SD MVFR CIGS WILL SPREAD FROM SW
TO NE DURING AM HOURS. AREAS OF LGT SNOW WILL OVERSPREAD REGION THIS
MORNING AND CONTINUE INTO SUNDAY NIGHT.

&&

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

$$