Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 261627
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1027 AM MDT WED AUG 26 2015

.UPDATE...
ISSUED AT 1011 AM MDT WED AUG 26 2015

UPPER LEVEL RIDGE IN PLACE ACROSS THE CENTRAL AND SOUTHERN ROCKIES
WITH WEAK SHORTWAVE LIFTING NORTH ACROSS UTAH. SKIES ARE PARTLY
CLOUDY ACROSS THE NORTHERN PLAINS WITH SOME WEAK MID LEVEL
INSTABILITY CROSSING THE AREA...PRODUCING WEAK ECHOES ON RADAR.
SURFACE LOW WILL DEVELOP ACROSS CENTRAL WYOMING THIS
AFTERNOON...AS THE UPPER WAVE APPROACHES. EASTERLY BOUNDARY LAYER
FLOW ACROSS THE SOUTH DAKOTA PLAINS WILL KEEP TEMPERATURES FROM
REACHING FULL POTENTIAL...ALONG WITH SOME SMOKE...SO HAVE TRIMMED
BACK TEMPERATURES IN THAT AREA A FEW DEGREES...CLOSER TO 90.
ACROSS NORTHEAST WYOMING AND FAR SOUTHERN SOUTH DAKOTA...SOUTH OF
THE WARM FRONT...ATMOSPHERE WILL BE WELL MIXED...WITH HIGH
TEMPERATURES IN THE MID 90S. BY LATE IN THE DAY...UPPER LEVEL
SHORTWAVE WILL LIFT THROUGH WYOMING...PRODUCING SOME ISOLATED
SHOWERS AND THUNDERSTORMS ACROSS NORTHEAST WYOMING...POSSIBLY
REACHING THE BLACK HILLS AREA LATE IN THE AFTERNOON. SHOWER AND
THUNDERSTORM ACTIVITY WILL INCREASE ACROSS THE AREA THIS EVENING
WITH A FEW STRONG STORMS POSSIBLE.

&&

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
ISSUED AT 156 AM MDT WED AUG 26 2015

UPPER RIDGE PERSISTS OVER THE WESTERN 2/3 OF THE CONUS...WITH
HIGH PRESSURE CENTERED OVER CO/NM AND NEXT UPPER WAVE NOW MOVING
THROUGH THE FOUR CORNERS REGION. HIGH CLOUDS ARE STREAMING INTO
THE NORTHERN PLAINS. AT THE SURFACE...WINDS ARE LIGHT AND
VARIABLE...AND TEMPS ARE IN THE 50S AND 60S.

ENVIRONMENT WILL BECOME INCREASINGLY UNSTABLE TODAY AS SOUTHEASTERLY
WINDS BRING IN WARM MOIST AIR AHEAD OF THE NEXT LOW. TEMPS WILL RISE
INTO THE UPPER 80S TO UPPER 90S...WITH DEW POINTS IN THE 50S TO
LOWER 60S. NAM IS STILL SHOWING MORE INSTABILITY THAN THE GFS AND
ECM...WITH NEAR 3000 J/KG MLCAPE...BUT CONSENSUS REMAINS ABOUT THE
BEST INSTABILITY STRETCHING ACROSS THE WESTERN/CENTRAL SD PLAINS IN
THE AFTERNOON AND EVENING. HOWEVER...A STRONG CAP IN PLACE MAY
INHIBIT MUCH STORM DEVELOPMENT. A FEW THUNDERSTORMS MAY DEVELOP OFF
THE BLACK HILLS IN THE AFTERNOON AND MOVE EASTWARD THROUGHOUT THE
EVENING...AND 0-6KM SHEAR WILL BE SUFFICIENT FOR ISOLATED SEVERE
STORMS TO DEVELOP.

UPPER WAVE WILL MOVE OVER THE REGION TONIGHT...AND WITH INCREASING
FORCING AND MOISTURE...EXPECT SCATTERED SHOWERS AND STORMS TO EXPAND
ACROSS THE AREA TONIGHT INTO THURSDAY. 700MB LOW IS PROGGED TO CLOSE
OFF EARLY THURSDAY MORNING OVER WESTERN SD WITH COOLER AIR WRAPPING
AROUND THE LOW. HIGHS WILL BE TRICKY ON THURSDAY DEPENDING ON THE
EFFECT OF THE COOLER AIR DURING PEAK HEATING TIME...BUT GENERALLY
HIGHS IN THE MID 70S TO MID 80S ARE EXPECTED. LOW DEEPENS THURSDAY
EVENING AS IT TRANSITIONS EASTWARD...RESULTING IN A SHARPER CUTOFF
OF PRECIP WITH MUCH OF THE WESTERN CWA DRYING OUT AND PRECIP
CONTINUING THURSDAY NIGHT FOR SOUTH CENTRAL SD.

.LONG TERM...FRIDAY THROUGH TUESDAY
ISSUED AT 156 AM MDT WED AUG 26 2015

LINGERING MOISTURE AND DECENT INSTABILITY/UPSLOPE FLOW
INTO THE BLKHLS ON FRIDAY COULD LEAD TO A FEW AFTN TSTMS IN THAT
AREA. OTHERWISE...UPPER RIDGE WILL REAMPLIFY ACROSS THE CNTRL CONUS
AND LEAD TO DRY AND HOT CONDITIONS THROUGH MOST OF THE WEEKEND.
RIDGE AXIS WILL THEN SHIFT EAST OF THE REGION EARLY NEXT WEEK...WITH
SW FLOW ALOFT RESULTING IN SMALL CHANCES OF STORMS AT TIMES ALONG
WITH SLIGHTLY COOLER TEMPS.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING
ISSUED AT 156 AM MDT WED AUG 26 2015

VFR CONDITIONS ARE EXPECTED MUCH OF THE DAY...ALTHOUGH
ISOLD-SCT TSRA ARE POSSIBLE OVER NERN WY AND THE BLKHLS IN THE LATE
AFTN/EVNG...WITH ISOLD MVFR CIGS. BETTER CHANCE FOR TSRA TONIGHT
ACROSS MUCH OF THE AREA WITH MVFR CONDITIONS POSSIBLE.


&&

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

$$

UPDATE...15
SHORT TERM...POJORLIE
LONG TERM...JOHNSON
AVIATION...JOHNSON



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