Area Forecast Discussion
Issued by NWS Rapid City, SD

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792
FXUS63 KUNR 122225
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
325 PM MST FRI FEB 12 2016

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 325 PM MST FRI FEB 12 2016

CURRENT SURFACE ANALYSIS SHOWS FRONTAL BOUNDARY NEARLY
STATIONARY FROM CENTRAL MT TO NORTHEAST WY TO FAR WESTERN NEB.
ARCTIC HIGH PRESSURE IS CENTERED OVER SOUTH CENTRAL CANADA. UPPER
LEVEL ANALYSIS SHOWS DEEP LOW OVER SOUTHERN HUDSON BAY...WITH LARGE
SCALE TROF COVERING EASTERN NORTH AMERICA. RIDGE AXIS TO THE WEST OF
THE AREA IS CENTERED OVER THE GREAT BASIN REGION. FAST AND ACTIVE
NORTHWEST FLOW IN PLACE ACROSS THE NORTHERN PLAINS TO THE MS RIVER
VALLEY.

CLOUDS COVER MUCH OF THE CWA...WITH LOW CLOUDS ACROSS MUCH OF THE
WESTERN SD IN UPSLOPE EAST-NORTHEAST FLOW. AREAS OF FOG AND PATCHY
FREEZING DRIZZLE MAINLY BANKED UP AGAINST THE NORTHERN AND EASTERN
SLOPES OF THE BLACK HILLS AND ADJACENT PLAINS AT THIS TIME. KUDX
RADAR SHOWS MOSTLY SOME LIGHT SNOW SHOWERS OVER FAR NORTHEAST WY AND
FAR WESTERN SD. TEMPS ARE MAINLY IN THE 20S OVER WESTERN SD...WITH
30S AND LOWER 40S OVER NORTHEAST WY.

ACTIVE PATTERN WILL CONTINUE THROUGH THE WEEKEND AS NORTHWEST FLOW
ALOFT CONTINUES TO BRING DISTURBANCES ACROSS THE AREA. THE BEST
CHANCE FOR PCPN WILL COME SATURDAY AFTERNOON AND EVENING AS A
STRONGER SHORTWAVE DISTURBANCE CROSSES THE AREA. THIS DISTURBANCE
WILL HELP TO PUSH THE FRONT EASTWARD ACROSS THE REGION AS A WARM
FRONT SATURDAY AND SATURDAY NIGHT. AS A RESULT...A MIX OF PCPN CAN
BE EXPECTED ACROSS THE AREA.

FOR TONIGHT...THE FRONT WILL REMAIN ACROSS NORTHEAST WY...BEGINNING
TO SLIDE EAST LATE TONIGHT. WEAK ENERGY ALOFT WILL INTERACT WITH THE
RELATIVELY TIGHT BAROCLINIC ZONE IN PLACE TO THE EAST OF THE FRONT
TO BRING SOME SNOW SHOWERS...AND POSSIBLY A BIT OF LIGHT FREEZING
RAIN IN A FEW SPOTS AROUND THE BLACK HILLS AREA AS WARMER AIR ALOFT
BEGINS TO SURGE EASTWARD. AREAS OF FOG WILL LIKELY PERSIST ACROSS
THE NORTHERN AND EASTERN SLOPES OF THE BLACK HILLS AND ADJACENT
PLAINS TONIGHT...WITH PATCHY FOG ELSEWHERE. SOME LIGHT FREEZING
DRIZZLE WILL ALSO CONTINUE...ESPECIALLY ACROSS WEST CENTRAL SD.

PCPN CHANCES WILL INCREASE ACROSS THE AREA SATURDAY...ESPECIALLY IN
THE AFTERNOON...AS SHORTWAVE MOVES ACROSS MT AND INTO THE DAKOTAS.
FRONT WILL SLOWLY MOVE EAST ACROSS THE BLACK HILLS AREA AND FAR
WESTERN SD DURING THE DAY. WARMEST TEMPS WILL BE ACROSS NORTHEAST WY
AND THE BLACK HILLS AREA DURING THE DAY...WITH COLDEST AIR TOWARD
CENTRAL SD. HIGHS WILL RANGE FROM AROUND 30 OVER CENTRAL SD TO THE
LOWER 50S OVER NORTHEAST WY AND FAR SOUTHWEST SD. PCPN TYPE WITH THE
SYSTEM WILL MAINLY BE RAIN ACROSS NORTHEAST WY AND FAR WESTERN
SD...WITH A MIXED BAG OF PCPN TO THE NORTH AND EAST. ACROSS
NORTHEASTERN PORTIONS OF THE CWA...FREEZING RAIN AND SNOW IS
LIKELY...ESPECIALLY ACROSS PERKINS AND ZIEBACH COUNTIES. NOT SURE AT
THIS POINT WHICH PCPN TYPE WILL BE DOMINANT...BUT SOME ICE AND SNOW
ACCUMULATION CAN BE EXPECTED IN THESE AREAS...SO WENT AHEAD AND PUT
OUT A WINTER WX ADVISORY FOR THOSE COUNTIES FOR TOMORROW. MAY NEED
TO EXPAND THE ADVISORY A BIT FURTHER SOUTH AND EAST DEPENDING ON THE
TRACK OF HEAVIER PCPN...BUT CONFIDENCE TOO LOW RIGHT NOW. BULK
OF PCPN WILL QUICKLY MOVE EAST OF THE AREA BY MIDNIGHT.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 325 PM MST FRI FEB 12 2016

NORTHWESTERLY FLOW ALOFT WILL PERSIST ACROSS THE NORTHERN PLAINS
THROUGH THE EXTENDED PERIOD AS AN UPPER RIDGE REMAINS IN PLACE
OVER THE WESTERN CONUS. STRONGEST SHORTWAVE DEPARTS THE AREA EARLY
SUNDAY...WITH LEFT OVER -SHRA/-SHSN FOR PORTIONS OF NORTHEAST
WYOMING INTO THE BLACK HILLS. WEAK DISTURBANCES IN THE NORTHWEST
FLOW MONDAY/TUESDAY MAY BRING SOME LIGHT PRECIPITATION ACROSS THE
AREA...WITH BEST CHANCE IN UPSLOPE FLOW ACROSS NORTHERN BLACK
HILLS. DRY CONDITIONS WITH TEMPERATURES WELL ABOVE AVERAGE
EXPECTED FOR THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING
ISSUED AT 325 PM MST FRI FEB 12 2016

WIDESPREAD MVFR/IFR CIGS WILL CONTINUE OVER WESTERN AND CENTRAL
SOUTH DAKOTA THROUGH TONIGHT...WITH LIFR CONDITIONS AROUND THE BLACK
HILLS. FZFG/FZDZ WILL CONTINUE ACROSS PORTIONS OF WESTERN SOUTH
DAKOTA TONIGHT. CONDITIONS WILL IMPROVE ACROSS NORTHEAST
WYOMING/SOUTHWEST SOUTH DAKOTA SATURDAY MORNING. MVFR/IFR CONDITIONS
WILL PERSIST THROUGH THE DAY ACROSS NORTHWEST INTO SOUTH CENTRAL
SOUTH DAKOTA WITH A WINTRY MIX OF SNOW AND FREEZING RAIN.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY FROM 8 AM TO 8 PM MST SATURDAY FOR
     SDZ002-014.

WY...NONE.
&&

$$

SHORT TERM...26
LONG TERM...7
AVIATION...7



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