Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 311540
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
940 AM MDT SUN AUG 31 2014

.UPDATE...
ISSUED AT 940 AM MDT SUN AUG 31 2014

CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE OVER SOUTHEAST
ND...WITH COLD FRONT WELL EAST OF OUR FORECAST AREA. UPPER LEVEL
ANALYSIS SHOWS BROAD TROF OVER THE WESTERN CONUS...WITH A SERIES
OF SHORTWAVES WITHIN THE TROF MOVING EAST THROUGH THE ROCKIES AND
PLAINS. LAST NIGHTS WAVE HAS MOVED WELL EAST OF THE AREA...BUT
ANOTHER IS MOVING THROUGH WESTERN NEB INTO PORTIONS OF SOUTHWEST
AND SOUTH CENTRAL SD NOW. YET ANOTHER DISTURBANCE IS NOTED OVER
WESTERN INTO CENTRAL WY...MOVING QUICKLY EASTWARD. KUDX RADAR
SHOWS BULK OF SHOWER ACTIVITY RIGHT NOW IS LOCATED OVER FAR
SOUTHWEST INTO SOUTH CENTRAL SD...WITH ISOLATED SHOWERS ELSEWHERE
TO THE NORTH AND WEST. TEMPS ARE IN THE UPPER 50S AND 60S ACROSS
MOST OF THE AREA WITH LIGHT WEST TO NORTHWEST WINDS.

SHOWERS AND ISOLATED THUNDERSTORMS OVER SOUTHEASTERN PORTIONS OF
THE CWA WILL MOVE EAST THROUGH THE LATE MORNING AND MIDDAY HOURS
AND EVENTUALLY EXIT EAST OF THE AREA. HOWEVER...SHOWERS AND
ISOLATED STORMS WILL CONTINUE TO DEVELOP AND INCREASE IN COVERAGE
FROM WEST TO EAST THROUGH THE MIDDAY AND AFTERNOON HOURS AS THE WY
SYSTEM MOVES EAST OVER THE AREA. THE BEST CHANCES FOR SHOWERS AND
MORE SIGNIFICANT RAINFALL WILL GENERALLY BE OVER THE BLACK HILLS
AREA AND SURROUNDING PLAINS. WITH CLOUD COVER AND RELATIVE LACK OF
WARMING TODAY...THE THREAT FOR SEVERE WEATHER SHOULD BE MINIMAL AT
BEST...WITH A STRONG STORM POSSIBLE OVER FAR SOUTHWEST AND SOUTH
CENTRAL SD THIS AFTERNOON. HIGHS WILL MOSTLY BE IN THE 70S ACROSS
THE SD PLAINS...WITH 60S OVER NORTHEAST WY AND THE BLACK HILLS.
SHOWERS WITH THIS SYSTEM SHOULD GRADUALLY DISSIPATE AND MOVE EAST
OF THE AREA DURING THE EVENING.

HAVE UPDATED TO RAISE POPS OVER MUCH OF THE AREA THROUGH THE DAY
AND TO LOWER HIGH TEMPS A BIT OVER EASTERN AREAS. ALSO MADE
ADJUSTMENTS TO CLOUD COVER AND DEWPOINTS THROUGH THE AFTERNOON.

&&

.SHORT TERM...TODAY THROUGH MONDAY NIGHT
ISSUED AT 300 AM MDT SUN AUG 31 2014

LONGWAVE TROUGH AXIS IS CROSSING MT SOUTH TO WY WITH SEVERAL
EMBEDDED WAVES ROUNDING THE BASE OVER WY. IR SAT/NEIGHBORING RADAR
SHOWS SHRA OVER WY QUICKLY PUSHING EWD. MEANWHILE OVER THE
CWA...SMALL SCALE SUBSIDENCE BEHIND THE WAVE DEPARTING E OF THE CWA
IS LEAVING QUIET WEATHER OVER THE AREA ATTM. THE TROUGH AXIS WILL
CROSS THE CWA TODAY BRINGING SHRA/TSRA TO THE AREA. MLCAPE WILL BE
WEAKER THAN YESTERDAY...500 TO 1000 J/KG TODAY WITH LITTLE TO NO
CAP...STILL ENOUGH FOR SOME STORM DEVELOPMENT. STRONG FORCING W/
THIS WAVE WARRANTS KEEPING AND EXPANDING LIKELY POPS OVER MUCH OF
THE CWA. GIVEN THE SPEED OF THIS SYSTEM...QPF IS EXPECTED TO BE
UNDER A HALF INCH. TEMPERATURES WILL BE A COOL 60S OVER NE WY AND
THE BLACK HILLS...ESPECIALLY AS CLOUDS REMAIN OVER THOSE AREA MUCH
OF THE DAY. THE SD PLAINS ARE EXPECTED TO REACH INTO THE 70S AND
MORNING HEATING COMMENCES BEFORE THE CLOUDS ROLL IN. BREEZY NW
WINDS WILL DEVELOP AS THE SYSTEM MOVES THROUGH WITH REINFORCING
COLD AIR ADVECTION.

SEVERAL UPPER WAVES DIVING DOWN THE BACKSIDE OF THE UPPER TROUGH
OVER THE NRN ROCKIES REGION WILL SLOW DOWN THE EWD PROGRESSION OF
THE OVERALL PATTERN. A SERIES OF WAVES ARE PROGGED TO CROSS THE CWA
MONDAY...WITH A REPEAT OF SHOWERS/STORMS CROSSING THE AREA THROUGH
THE DAY. WITH WEAKER FORCING AND LESS MOISTURE IN THE
ATMOSPHERE...WILL GO WITH CHANCE POPS FOR SHRA ACTIVITY. MLCAPE WILL
BE WEAKER MONDAY THAN TODAY...BUT COULD STILL SEE ISOLATED STORMS.
TEMPERATURES WILL BE IN THE MID 60S TO UPPER 70S. PRECIP WILL END
OVER THE AREA BY LATE MON NIGHT.

&&

.LONG TERM...TUESDAY THROUGH SATURDAY
ISSUED AT 300 AM MDT SUN AUG 31 2014

UPPER TROUGH DIGS ACROSS THE PACIFIC NORTHWEST TUESDAY/WEDNESDAY...
BRINGING FLAT UPPER RIDGE OVER THE NORTHERN PLAINS. THIS WILL
RESULT IN DRY CONDITIONS WITH TEMPERATURES NEAR OR SLIGHTLY ABOVE
AVERAGE. STRONG WAVE LIFTS ACROSS THE NORTHERN ROCKIES LATE
WEDNESDAY/THURSDAY...PUSHING COLD FRONT THROUGH THE NORTHERN
PLAINS. BEST FORCING STAYS NORTH OF FORECAST AREA...THOUGH A FEW
POST FRONTAL SHOWERS/THUNDERSTORMS POSSIBLE THURSDAY. MODELS
DIVERGE FOR THE WEEKEND...WITH ECMWF BRINGING STRONG SHORTWAVE IN
NORTHWEST FLOW SATURDAY...WHILE GFS MAINTAINS UPPER TROF OVER
WESTERN CONUS AND RIDGING OVER THE PLAINS. TRENDED TOWARDS
ECMWF...WITH COOLER TEMPERATURES AND SMALL POPS.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING
ISSUED AT 300 AM MDT SUN AUG 31 2014

SCATTERED SHOWERS AND THUNDERSTORMS WILL BE FOUND ACROSS THE AREA
TODAY. LCL MVFR CIGS/IFR VSBY POSSIBLE WITH THE STRONGER STORMS.


&&

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

$$

UPDATE...26
SHORT TERM...13
LONG TERM...7
AVIATION...7






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