Area Forecast Discussion
Issued by NWS Rapid City, SD

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KUNR 211725
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1125 AM MDT SUN SEP 21 2014

.SHORT TERM...TODAY THROUGH MONDAY NIGHT
ISSUED AT 205 AM MDT SUN SEP 21 2014

SFC RIDGE WILL SHIFT SE OF THE REGION TODAY AS THE SW
CONUS UPPER LOW EJECTS TOWARD THE NORTHERN PLAINS. LL WAA WILL
SUPPORT AN EASTWARD SHIFT OF THE WESTERN NOAM RIDGE AS SOUTHERLY
RETURN FLOW REVS UP. DEEP MOISTURE PLUME ASSOCIATED WITH THE
EJECTING LOW WILL ADVECT INTO THE REGION LATER TONIGHT...WITH POS
THETA-E ADV PREVAILING THROUGH MONDAY. INCREASING MOISTURE AND LSA
WILL SUPPORT ISOLD TO SCT SHOWERS AND THUNDERSTORMS ACROSS MUCH OF
THE AREA MONDAY...ESP THE SE FA AS THE SW CONUS UPPER LOW EJECTS NE
ACROSS THE AREA WITH AN ASSOCIATED THETA-E RIDGE.

TODAY...DRY AND SUNNY WEATHER ON TAP AS UPPER LEVEL RIDGING
CONTINUES ACROSS THE NORTHERN PLAINS. SEASONAL TEMPS ALL PLACES WITH
HIGHS IN THE 70S UNDER GENERALLY LIGHT WINDS. LL PRESSURE FALLS WILL
CONTINUE THROUGH TONIGHT WITH DEEP LAYER POS THETA-E ADV PER THE
ADVANCING SW CONUS UPPER TROUGH AND ASSOCIATED MOISTURE PLUME. GUSTY
WINDS EXPECTED ACROSS NE WY AND POSSIBLY THE NORTHERN BH FOOTHILLS
OVERNIGHT GIVEN MAGNITUDE OF PRESSURE FALLS. LACK OF APPRECIABLE
FORCING FOR ASCENT WITH RELATIVELY STABLE PROFILES PER ELEVATED
CONVECTION PRECLUDES ANY POP MENTION TONIGHT. HAVE OPTED DRY ALL
PLACES.

MONDAY...DEEP LAYER MOISTURE PLUME WILL SHIFT NE OVER THE FA WITH
DIURNAL HEATING SUPPORTING DESTABILIZATION. HOWEVER...EXPECTED MID
LEVEL CLOUD COVER MAY HAMPER THIS PROCESS...LEAVING SOME DOUBT TO
THE DEGREE OF INSTABILITY OUTSIDE NE WY. INCREASING LSA PER THE
ADVANCING IMPULSE WILL SUPPORT INCREASING CHANCES FOR SHRA/TS MOST
PLACES. HOWEVER...LACK OF APPRECIABLE INSTABILITY WITH THE BULK OF
FORCING SHIFTING TOWARD SCENTRAL SD SUPPORTS MOSTLY LOW CHANCE TO
SLIGHT CHANCE POPS ACROSS MOST OF THE FA THROUGH MON NIGHT...SAVE
FOR SCENTRAL SD WHERE OVERLAP OF STRONGER DYNAMIC FORCING/DEEP
MOISTURE WILL BE FOUND. ANY ACTIVITY OVER THE NW HALF OF THE FA IS
EXPECTED TO MAINLY DIURNALLY FORCED AND MORE OF A WIDELY SCT TO
ISOLD NATURE. DID RAISE POPS OVER SCENTRAL SD TO HIGH CHANCE AND
LIKELIES...ESP TOWARD TRIPP COUNTY. CONVECTIVE ACTIVITY WILL HAVE
PLENTY OF MOISTURE TO WORK WITH...WITH FORECAST MODELS SUPPORTING
WELL OVER AN INCH OF PW. HENCE LOCALIZED HEAVY RAIN IS
POSSIBLE...ESP OVER SCENTRAL SD. OTHERWISE...MAINLY SEASONAL
CONDITIONS WILL CONTINUE WITH HIGHS IN THE 70S AND LOWS IN THE 50S.

&&

.LONG TERM...TUESDAY THROUGH SATURDAY
ISSUED AT 205 AM MDT SUN SEP 21 2014

SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO
TUESDAY...AND THEN DIMINISH IN THE EVENING AS THE LOW MOVES EAST.
DRIER AIR WILL RETURN WEDNESDAY AS A RIDGE BUILDS...AND HIGHS WILL
BE ABOVE AVERAGE FOR THE SECOND HALF OF THE WORKWEEK. THE ECM AND
GFS CONTINUE TO SHOW A SECONDARY UPPER LOW DEVELOPING AND
RETROGRADING BACK OVER THE NRN PLAINS. THE GFS KEEPS THIS LOW
FARTHER SOUTH...WHILE THE ECM HAS IT LINGERING OVER WESTERN SD
BEFORE IT GETS PUSHED BACK INTO THE MAIN FLOW. ALSO THE GFS IS
QUICKER THAN THE ECM WITH BRINGING EASTWARD THE BROAD TROUGH OVER
THE WESTERN CONUS. DECIDED TO INTRODUCE SOME SLIGHT CHANCE POPS FOR
NEXT WEEKEND.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY)
ISSUED AT 1124 AM MDT SUN SEP 21 2014

VFR CONDITIONS ARE EXPECTED THROUGH MONDAY MORNING. ISLD TO SCT
-SHRA/-TSRA WILL DEVELOP ACROSS PORTIONS OF NE WY TO SW SD MONDAY
MORNING...WITH MVFR CONDITIONS POSSIBLE IN THE HEAVIER PRECIP.
WINDS WILL BECOME BREEZY FROM THE SOUTH TONIGHT INTO MONDAY.

&&

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

$$

SHORT TERM...JC
LONG TERM...POJORLIE
AVIATION...13






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.