FXUS63 KUNR 050911
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
211 AM MST SUN FEB 5 2012

.DISCUSSION...09Z SURFACE ANALYSIS HAS HIGH PRESSURE OVER THE
CENTRAL AND NORTHERN PLAINS WITH LEE TROF DEVELOPING OVER CENTRAL
MONTANA AND NORTHEASTERN WYOMING. TEMPERATURES ARE CURRENTLY IN
THE TEENS TO MID 20S WITH LIGHT WEST TO SOUTHWEST WINDS. UPPER
LEVEL ANALYSIS HAS LARGE REX BLOCK OVER THE WESTERN CONUS.

BLOCKING PATTERN WILL KEEP THE FORECAST AREA DRY AND MILD FOR
TODAY. MILDER AIR WILL PUSH INTO THE AREA TODAY WITH HIGHS WELL
INTO THE 40S. SOME LOCATIONS WILL PUSH 50 DEGREES. SKIES WILL BE
SUNNY. CLEAR SKIES AND DRY CONDITIONS WILL ALLOW TEMPERATURES TO
FALL INTO THE TEENS AND LOWER 20S TONIGHT.

FOR MONDAY...STRONG UPPER TROF WILL DROP SOUTH OUT OF CANADA
MONDAY AFTERNOON. ASSOCIATED SURFACE COLD FRONT WILL PUSH ACROSS
THE AREA THROUGH THE DAY...WITH BREEZY CONDITIONS AND COLDER AIR
IN ITS WAKE. WEAK SHORTWAVE ENERGY CROSSES THE NORTHERN ROCKIES
AND SLIDES INTO THE AREA MONDAY EVENING...BRINGING SOME LIGHT SNOW
TO MAINLY WESTERN PARTS OF THE AREA. WITH THE NORTHERLY FLOW AND
MOISTURE AVAILABLE FROM THIS WAVE...COULD BE SOME UPSLOPE ENHANCED
SNOWS ACROSS THE NORTHERN BLACK HILLS MONDAY NIGHT. AT THIS
TIME...ACCUMULATIONS LOOK TO BE ONLY AN INCH OR TWO. HIGH
TEMPERATURES WILL ONLY BE IN THE 30S ACROSS NORTHERN AND WESTERN
AREAS...AS COLD FRONT WILL MOVE THROUGH EARLY MONDAY MORNING.
TEMPERATURES SHOULD RISE INTO THE 40S ACROSS SOUTHERN AND SOUTH
CENTRAL SOUTH DAKOTA...WHERE COLD FRONT WILL MOVE THROUGH LATER IN
THE DAY.

ON TUESDAY...WEAK SHORTWAVE SHIFTS SOUTH OF THE FORECAST AREA BY
MIDDAY WITH CLOUD COVER ON THE DECREASE BY THE AFTERNOON.
TEMPERATURES REMAIN COLD IN THE WAKE OF THE SYSTEM...AS 1038MB
CANADIAN HIGH BUILDS INTO THE NORTHERN PLAINS. HIGHS WILL ONLY BE
IN THE 20S TO LOWER 30S WITH LIGHT EASTERLY BOUNDARY LAYER FLOW.

EXTENDED...UPPER FLOW BECOME NORTHWESTERLY FOR THE LAST HALF OF THE
WEEK WITH DEEP POLAR VORTEX OVER HUDSON BAY. GFS/ECMWF SIMILAR IN
KEEPING BULK OF ARCTIC AIR EAST OF THE AREA...WITH HIGH DROPPING
ACROSS EASTERN DAKOTAS/MINNESOTA. DEPTH OF ARCTIC AIR WILL ALLOW IT
TO BACK INTO WESTERN SOUTH DAKOTA. SOME QUESTION AS TO HOW COLD IT
COULD GET. GEFS STILL SHOWING 850MB TEMPERATURE SPREADS OF 15-20C
ACROSS WESTERN SOUTH DAKOTA. HOWEVER...OTHER THAN A FEW MEMBERS ON
EITHER EXTREME...THE MAJORITY OF MEMBERS ARE NEAR THE MEAN. UPPER
FLOW BECOMES WESTERLY FOR THE WEEKEND...WITH A RETURN TO ABOVE
AVERAGE TEMPERATURES.

&&

.AVIATION...12Z TAFS
VFR CONDITIONS EXPECTED THROUGH TONIGHT.

&&

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

$$

SHORT TERM...15
LONG TERM....07
AVIATION...07


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