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000
FXUS63 KUNR 121114
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
514 AM MDT WED JUN 12 2013

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
ISSUED AT 308 AM MDT WED JUN 12 2013

WATER VAPOR IMAGERY SHOWS A CUT OFF LOW ACROSS THE PACIFIC
NORTHWEST...AND WEAK RIDGING ACROSS THE NORTHERN HIGH PLAINS IN
THE WAKE OF THE SHORTWAVE NOW CROSSING EAST RIVER SD INTO
MINNESOTA. SURFACE ANALYSIS SHOWS HIGH PRESSURE FROM MONTANA TO
COLORADO.

HIGH PRESSURE WILL SLIDE INTO CENTRAL SOUTH DAKOTA TODAY BRINGING
QUIET WEATHER TO THE AREA FOR MUCH OF THE DAY TODAY. RETURN FLOW
WILL SET BACK UP FROM EASTERN MONTANA INTO NORTHEAST WYOMING AND
WESTERN SOUTH DAKOTA. TEMPERATURES IN THE 70S TO LOWER 80S ARE AGAIN
EXPECTED. UNSTABLE AIRMASS WILL REDEVELOP THIS AFTERNOON WITH MLCAPE
RANGING FROM 800 TO 1500 J/KG...AND WITH WEAKER CAPPING THAN
YESTERDAY. LOW LEVEL SHEAR WILL RAMP UP THROUGH THE LATE AFTERNOON
AND EVENING AS THE RETURN FLOW/LLJ STRENGTHENS. ISOLATED STORMS MAY
INITIATE OVER THE BLACK HILLS THIS AFTERNOON. OTHERWISE A SERIES OF
WAVES PUSHING INTO WESTERN WYOMING AND MONTANA WILL BRING
THUNDERSTORMS TOWARD THE BIG HORNS INTO CENTRAL MONTANA LATE THIS
AFTERNOON INTO TONIGHT. A DRYLINE WILL SET UP SOMEWHERE ACROSS
CENTRAL TO NORTHEASTERN WYOMING...AND THIS COULD BE THE FOCUS FOR
MORE CONVECTION. SUFFICIENT SHEAR WILL SUPPORT SUPERCELL DEVELOPMENT
LARGE HAIL AND DAMAGING WINDS POSSIBLE. THE BULK OF CONVECTION WILL
END BY 06Z...HOWEVER SOME LINGERING STORMS WILL BE POSSIBLE
OVERNIGHT WITHIN THE BAND OF THETA E ADVECTION AND LOW LEVEL JET
ACROSS WESTERN SOUTH DAKOTA.

STRENGTHENING ACTIVE SOUTHWEST FLOW ALOFT IS EXPECTED THURSDAY WITH
THE APPROACH OF THE NEXT TROUGH. SURFACE LOW WILL ALSO STRENGTHEN
NEAR THE MONTANA TO WYOMING BORDER LATE IN THE DAY ALONG A
BAROCLINIC ZONE. STRONG THETA E ADVECTION WILL CONTINUE ACROSS THE
CWA AHEAD OF THE SURFACE LOW. MOST LOCATIONS WILL SEE TEMPERATURES
REACH THE 80S AND DEWPOINTS REACHING THE UPPER 50S TO LOWER 60S. THE
SURFACE LOW WILL PUSH ACROSS EASTERN MONTANA THURSDAY AFTERNOON...AND
INTO THE DAKOTAS THURSDAY NIGHT. A SERIES OF UPPER WAVES WILL
COMBINE WITH A COLD FRONT CROSSING THE AREA TO BRING ANOTHER ROUND
OF THUNDERSTORMS. LOW LEVEL JET WILL CONTINUE ACROSS WESTERN SOUTH
DAKOTA...WHICH WILL AGAIN RESULT IN ENOUGH SHEAR FOR SUPERCELL
DEVELOPMENT. LARGE HAIL AND DAMAGING WINDS WILL BE THE MAIN THREATS
THURSDAY. CONVECTION WILL PUSH NORTHEASTWARD OVERNIGHT...CLEARING
THE CWA LATE THURSDAY NIGHT.

&&

.LONG TERM...FRIDAY THROUGH TUESDAY
ISSUED AT 308 AM MDT WED JUN 12 2013

MEAN WESTERN CONUS TROUGHING WILL CONTINUE IN THE
PERIOD...WITH TEMPORARY WESTERN TROUGH REMOVAL FRI-SUN PER TROUGH
KICKING BY AN ADVANCING NORTHERN PAC UPPER TROUGH. RETAINED LOW CHANCES
FOR POPS FRI OVER NE WY AND FAR SE FA GIVEN WITH THE ADVECTION OF
THE MAIN UPPER TROUGH INTO SOUTHERN CANADA. THIS UPPER TROUGH WILL
FRACTURE OVER SOUTHERN MB/SK WITH THE REMAINING VORT LOBE SHIFTING
SE SUN. MEAN RIDGING FAVORED EARLY NEXT WEEK AHEAD OF RE-INITIATED
WESTERN CONUS TROUGHING...SUPPORTING A WARMING TREND WITH INCREASING
CHANCES FOR SHRA/TS AS WEAK DISTURBANCES ADVECT EAST OUT OF THE MEAN
WESTERN CONUS TROUGH. BEST CHANCES FOR ANY PRECIP LOOKS TO REMAIN
OVER NE WY AND SOUTHERN PORTIONS OF THE FA...GIVEN HIGH TERRAIN
INITIATION AND LL THETA-E RIDGING. KEPT POPS FAIRLY LOW GIVEN
CONCERNS ON IMPULSE STRENGTH/TRACK/AND LL MOISTURE RECOVERY.

NOT MUCH CHANGES TO PREVIOUS POP NUMBERS...RETAINING LOW NUMBERS
IN MOST PERIODS. MONDAY COULD END UP DRY MOST PLACES...ESP IF
RIDGING IS DELAYED. OTHERWISE...A TRANSITION TO SW FLOW EARLY NEXT
WEEK SUPPORTS A SMALL UPTICK IN POPS. GENERALLY NORMAL TEMPS
EXPECTED IN THE PERIOD. DEGREE OF CAA BEHIND SUNDAY/S WAVE STILL
WAVERING IN GFS/ECMWF SOLUTIONS WITH POTENTIALLY COOLER NUMBERS
POSSIBLE. HAVE SIDED SLIGHTLY BELOW NORMAL FOR MONDAY ATTM.
OTHERWISE...WARMING TREND LIKELY BEYOND MONDAY GIVEN EASTERN
TRANSLATION OF THE NEXT RIDGE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 509 AM MDT WED JUN 12 2013

IFR/LIFR CIGS WILL BE FOUND FROM NE WY NEAR W43...SE TO RAP AND IN
SURROUNDING AREAS NEAR THE BH. FLOW WILL VEER EASTERLY WHICH MAY
ALLOW CIGS TO PERSIST INTO EARLY AFTERNOON ALONG THE EASTERN BH
FOOTHILLS INCLUDING RAP. OTHERWISE...VFR CONDITIONS ARE EXPECTED
ACROSS THE REMAINDER OF THE REGION AS WEAK SFC HIGH PRESSURE
SHIFTS SOUTHEAST ACROSS THE CENTRAL DAKOTAS. ANOTHER MID LEVEL
IMPULSE IN SW FLOW MAY SUPPORT AN ISOLD TS LATE THIS AFTERNOON AND
OVERNIGHT FROM NE WY INTO NW SD.

&&

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

$$

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