Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 212047
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
147 PM MST WED JAN 21 2015

.SHORT TERM...THIS EVENING THROUGH THURSDAY NIGHT
ISSUED AT 127 PM MST WED JAN 21 2015

UPPER LEVEL ANALYSIS HAS POSITIVELY TILTED TROF ACROSS THE CENTRAL
CONUS WITH HIGH AMPLITUDE RIDGE MOVING ONTO THE WEST COAST. UPPER
TROF AXIS ACROSS THE NORTHERN PLAINS IS JUST SHIFTING SOUTH OF THE
DAKOTAS. SKIES ARE MOSTLY CLOUDY WITH LOCAL RADAR SHOWING LIGHT
ECHOES ACROSS PARTS OF THE SOUTH DAKOTA PLAINS...AND BETTER ECHOES
ACROSS THE NORTHERN BLACK HILLS AND FOOTHILLS. AT THE
SURFACE...TAIL END OF WEAK COLD FRONT REMAINS ACROSS SOUTHERN
SOUTH DAKOTA WITH HIGH PRESSURE BUILDING IN FROM THE NORTH.
TEMPERATURES ARE MAINLY IN THE 20S TO LOWER 30S...WITH BREEZY
NORTHWEST WINDS.

LATE THIS AFTERNOON/TONIGHT...UPPER TROF QUICKLY SHIFTS SOUTHEAST
AS RIDGE BUILDS ACROSS THE ROCKIES. CURRENT SNOW SHOWERS WILL
DIMINISH LATE THIS AFTERNOON...WITH DRIER AIR MOVING IN FOR THIS
EVENING. AS SURFACE HIGH MOVES IN...WINDS WILL ALSO DIMINISH THIS
EVENING...AND THEN BECOME SOUTHWEST AFTER MIDNIGHT ACROSS WESTERN
AREAS. SKIES WILL BECOME PARTLY CLOUDY...AND TEMPERATURES WILL
DROP...WITH LOW TEMPERATURES IN THE SINGLE DIGITS AND TEENS.

THURSDAY...UPPER RIDGE QUICKLY BUILDS INTO THE NORTHERN PLAINS AS
SOUTHWEST BOUNDARY LAYER FLOW PICKS UP. TEMPERATURES WILL REBOUND
NICELY ON THURSDAY...WITH HIGHS IN THE 30S AND 40S UNDER MOSTLY
SUNNY SKIES. UPPER RIDGE CONTINUES TO BUILD INTO THE NORTHERN
PLAINS THURSDAY NIGHT...WITH MOSTLY CLEAR SKIES EXPECTED. LOW
TEMPERATURES WILL BE MILDER...IN THE TEENS AND 20S.

.LONG TERM...FRIDAY THROUGH WEDNESDAY
ISSUED AT 127 PM MST WED JAN 21 2015

MODELS CONTINUE TO ALTERNATE BETWEEN PRECIP AND NO PRECIP FRIDAY
WITH THE WEAK WAVE THAT MOVES THROUGH. THE LATEST NAM/GFS/SREF
HAVE PRECIP FOR THE BLACK HILLS/NORTHEAST WY AND ALSO THE
CONVERGENCE ZONE OVER THE PINE RIDGE AREA. SOME FRONTOGENESIS AND
Q-VECTOR CONVERGENCE AROUND THESE AREAS...ALONG WITH INCREASING
MOISTURE FRIDAY MORNING MAY ALLOW FOR SOME LIGHT SNOW/RAIN
SHOWERS. DECIDED TO ADD SOME SLIGHT CHANCE POPS BACK IN.

A COUPLE OF WEAK FAST-MOVING WAVES WILL SWEEP THROUGH THE NORTHERN
PLAINS THIS WEEKEND...BRINGING BREEZY WINDS AND SOME LIGHT
RAIN/SNOW. STRONGEST ENERGY WILL BE TO THE EAST...AND SO CENTRAL SD
IS MORE LIKELY TO SEE PRECIP THAN SOME AREAS FARTHER WEST. ALSO HAVE
POPS FOR THE NORTHERN HILLS...AS FROUDE NUMBER INDICATES UPSLOPE
ENHANCEMENT. ABOVE AVERAGE TEMPERATURES ARE EXPECTED THROUGH THE
EXTENDED...WITH DRY WEATHER EARLY NEXT WEEK.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z THURSDAY
ISSUED AT 127 PM MST WED JAN 21 2015

MVFR/IFR CONDITIONS ARE EXPECTED THIS AFTERNOON ACROSS MUCH OF
THE AREA AS A SYSTEM CROSSES THE REGION BRINGING LIGHT SNOW.
CONDITIONS ARE EXPECTED TO IMPROVE TO VFR LATE TODAY INTO TONIGHT
AS DRIER AIR MOVES BACK IN FROM THE NW.

&&

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

$$

SHORT TERM...15
LONG TERM...POJORLIE
AVIATION...POJORLIE





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