Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 252250
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
450 PM MDT TUE AUG 25 2015

.SHORT TERM...THIS EVENING THROUGH WEDNESDAY NIGHT
ISSUED AT 230 PM MDT TUE AUG 25 2015

UPPER LEVEL ANALYSIS HAS A RIDGE OVER THE WESTERN 2/3 OF THE
CONUS...WITH AN UPPER LOW SPINNING JUST NORTH OF THE GREAT LAKES
REGION. A FEW MID LEVEL CLOUDS ARE STREAMING OVER THE RIDGE INTO
THE NORTHERN PLAINS. SURFACE HIGH PRESSURE STRETCHES ACROSS THE
EASTERN DAKOTAS WITH WEAK LOW PRESSURE CENTER OVER EASTERN
MONTANA. WINDS ARE 10 TO 20 MPH OUT OF THE SOUTHEAST...AND TEMPS
AT 2PM ARE IN THE 80S TO LOWER 90S.

TONIGHT...UPPER RIDGE REMAINS OVER THE AREA WITH MOSTLY CLEAR
SKIES EXPECTED. LOWS TONIGHT WILL BE IN THE 50S TO LOWER 60S.

WEDNESDAY...MODELS IN AGREEMENT THAT AN UPPER LEVEL SHORTWAVE
WILL APPROACH THE REGION LATE WEDNESDAY AS IT PASSES THROUGH THE
RIDGE. SOUTHEASTERLY WINDS WILL INCREASE AHEAD OF THE SURFACE
LOW/TROF ACROSS CENTRAL MONTANA AND WYOMING...ADVECTING IN
MOISTURE AND WARM AIR. TEMPS WILL RISE INTO THE MID 80S TO LOWER
90S...WITH DEW POINTS IN THE 50S TO LOWER 60S. NAM SHOWS NOTABLY
MORE PRECIP AND INSTABILITY THAN THE GFS AND ECM...BUT THERE IS
CONSENSUS ABOUT THE BEST INSTABILITY STRETCHING ACROSS THE
WESTERN/CENTRAL SD PLAINS IN THE LATE AFTERNOON AND EVENING.
HOWEVER...A STRONG CAP IN PLACE MAY INHIBIT MUCH STORM
DEVELOPMENT. 0-6KM SHEAR IN THIS AREA WILL BE 30-40 KTS...WITH
BETTER SHEAR FARTHER EAST. EXPECT SHOWERS AND THUNDERSTORMS TO
INCREASE ACROSS THE CWA WEDNESDAY EVENING AND OVERNIGHT AS THE
UPPER WAVE MOVES OVER THE AREA...WITH SOME ISOLATED SEVERE STORMS
POSSIBLE.

.LONG TERM...THURSDAY THROUGH TUESDAY
ISSUED AT 230 PM MDT TUE AUG 25 2015

A FAIRLY STRONG UPPER LOW WILL MOVE THROUGH THE CENTRAL CONUS
RIDGE AND CROSS THE NRN PLAINS...BRINGING A GOOD CHANCE OF PCPN TO
OUR AREA FROM WEDNESDAY NIGHT THROUGH THURSDAY. THE UPPER RIDGE IS
THEN EXPECTED TO QUICKLY REBUILD AND BRING ABOVE AVERAGE TEMPS
AGAIN FOR FRIDAY THROUGH THE WEEKEND. ALTHOUGH A FEW UPPER
IMPULSES MAY BRING A SMALL CHANCES FOR THUNDERSTORMS AT TIMES
DURING THE WEEKEND AND INTO EARLY NEXT WEEK...WDSPRD COVERAGE IS
NOT EXPECTED. THE ECMWF BREAKS DOWN THE RIDGE EARLY NEXT
WEEK...WHILE THE GFS DOES NOT...SO FCST CONFIDENCE REMAINS FOR THE
BEGINNING OF NEXT WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 449 PM MDT TUE AUG 25 2015

VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. ISOLD-SCT TSRA ARE
EXPECTED OVER NERN WY AND THE BLKHLS WEDS AFTN...WITH ISOLD MVFR
CIGS.

&&

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

$$

SHORT TERM...15
LONG TERM...10
AVIATION...BUNKERS



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