FXUS63 KUNR 042129
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
229 PM MST FRI DEC 4 2009

.DISCUSSION...20Z SURFACE ANALYSIS HAS CANADIAN HIGH PRESSURE
OVER THE CENTRAL CONUS WITH LEE TROF ACROSS CENTRAL MONTANA INTO
NORTHEAST WYOMING. TEMPERATURES HAVE CLIMBED INTO THE 20S FROM
VERY CHILLY LOWS THIS MORNING. WINDS REMAIN LIGHT. UPPER LEVEL
ANALYSIS HAS LARGE UPPER LOW OVER HUDSON BAY WITH ANOTHER UPPER
LOW STREAKING SOUTHEAST ACROSS SOUTHWEST CANADA.

COLD AND UNSETTLED WEATHER WILL REMAIN IN PLACE OVER THE NORTHERN
PLAINS THROUGH MUCH OF NEXT WEEK. LONG TERM MODELS SUGGEST A
POSSIBLE RETURN TO NEAR NORMAL TEMPERATURES BY NEXT WEEKEND.

TONIGHT...TEMPERATURES WILL DROP INTO THE SINGLE DIGITS AND TEENS
TONIGHT WITH SOME INCREASING CLOUDINESS AS SOUTHWEST CANADIAN
UPPER LOW MOVES INTO NORTHWESTERN MONTANA.

SATURDAY...COLD FRONT WILL PASS THROUGH EARLY SATURDAY AS UPPER
LOW SLIDES INTO WYOMING. BREEZY NORTHWEST WINDS WILL DEVELOP
BEHIND THE FRONT WITH COLDER AIR ADVECTING IN. HIGHS WILL BE
SIMILAR TO TODAY ACROSS SOUTH CENTRAL SOUTH DAKOTA...BUT A FEW
DEGREES COOLER ACROSS NORTHERN AND WESTERN AREAS. SOME LIGHT
SNOW WILL DEVELOP ACROSS THE AREA...WITH BEST CHANCES LOOKING
TO BE ACROSS NORTHEASTERN WYOMING AND FAR WESTERN SOUTH DAKOTA.
LIGHT UPSLOPE CONDITIONS WILL DEVELOP OVER THE NORTHERN BLACK
HILLS FROM SATURDAY MORNING THROUGH SATURDAY NIGHT. A FEW INCHES
OF ACCUMULATION WILL BE POSSIBLE. 

SUNDAY...SOME LIGHT SNOW WILL BE POSSIBLE AGAIN ON SUNDAY...WITH
BEST CHANCES AGAIN OVER NORTHEAST WYOMING AND THE BLACK HILLS.
HIGHS WILL ONLY BE IN THE TEENS AT MOST LOCATIONS ON
SUNDAY...WITH LOWS NEAR OR BELOW ZERO SUNDAY NIGHT IN MANY
LOCATIONS.

EXTENDED...AS UPPER LOW DROPS INTO SWRN US AND WEAKENS...AND 
NORTHERN PLAINS REMAIN UNDER SHORT WAVE TROF/CYCLONIC FLOW THROUGH 
THE END OF NEXT WEEK. MODELS BUILDING UPPER RIDGE OVER THE ROCKIES 
THAT WILL BRING WARMER TEMPS BY NEXT WEEKEND. ON THE SURFACE... 
ARCTIC HIGH PRESSURE WILL SLIDE SOUTHWARD...COMBINING WITH SW UPPER 
FLOW PRODUCING OVERRUNNING CONDITIONS AND OCCASIONAL LGT PRECIP. 
ANOTHER SURGE OF COLD AIR WILL ARRIVE MIDWEEK...KEEPING TEMPS WELL 
BELOW NORMAL.

&&

.AVIATION...CLDS WL INCRS OVERNIGHT...BUT MOST CIGS WL RMN VFR. SOME 
LOCALIZED MVFR VSBYS WL OCCUR WITH LGT SNW SHWRS. WNDS WL SWITCH TO 
THE NW AS COLD FRONT CROSSES THE AREA.

&&

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

$$