Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 031705
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1105 AM MDT THU SEP 3 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT
ISSUED AT 224 AM MDT THU SEP 3 2015

CENTRAL CONUS RIDGE WILL REMAIN IN PLACE THROUGH THE PERIOD AS
THE NW PAC UPPER TROUGH REMAINS NEARLY ANCHORED. DEEP LAYER SW
COMPRESSIONAL FLOW WILL SUPPORT A VERY WARM DAY ACROSS THE REGION
AS DEEP MIXING/CLEAR SKIES WILL ALLOW NEAR FULL TEMP POTENTIALS
THIS AFTERNOON. WEAK JET STREAK WILL MIGRATE NORTH INTO THE FA
LATE THIS AFTERNOON/EVENING...SUPPORTING INCREASING DEEP LAYER
ASCENT WITH INCREASING INSTABILITY. THE BEST CHANCE FOR PRECIP
WITH THIS SYSTEM WILL BE OVERNIGHT ACROSS THE FAR EAST.
HOWEVER...CANNOT RULE OUT A FEW ISOLD SHRA/TS THIS AFTERNOON
ACROSS SCENTRAL INTO CENTRAL SD...AND PERHAPS THE NORTHERN BLACK
HILLS WHERE SOME WEAK EDDY CONVERGENCE WILL BE IN PLACE. CONSENSUS
CAPE FIELDS SUGGEST 1-1.5 KL/KG ACROSS CENTRAL SD WITH MUCH LESSER
AMOUNT WEST WHERE DRY SW FLOW WILL BE IN PLACE. WEAK BULK DEEP
LAYER SHEAR WITH STEEP LL LAPSE RATES AND INVERTED V PROFILES WILL
SUPPORT A GUSTY WIND THREAT WITH ANY TS AND HAVE ADDED THIS
MENTION THIS AFTERNOON THROUGH EVENING...ESP GIVEN HIRES MODEL
OUTPUT. AS STATED ABOVE...BETTER CHANCES FOR SHRA/TS EXPECTED
OVERNIGHT TONIGHT AS THE MAIN MID LEVEL JET STREAK AND LL SFC
TROUGH CROSSES THE REGION. A FEW LINGER SHRA WILL BE POSSIBLE
ACROSS THE EASTERN HALF FRI MORNING. OTHERWISE...MAINLY DRY CONDS
EXPECTED FRI AFTERNOON...SAVE A SLIGHT CHANCE OF CONVECTION OVER
THE CENTRAL TO NORTHERN HILLS WITH WEAK INHIBITION AND INCREASED
LL MOISTURE. PAC NW UPPER TROUGH WILL SLOWLY SHIFT EAST AND
SUPPORT AN INCREASING POS THETA-E ADV REGIME FRIDAY NIGHT FROM A
LINGERING MONSOON IMPULSE...WITH POTENTIAL ELEVATED CONVECTION
ARRIVING ACROSS SW AREAS...SPREADING NE THROUGH THE NIGHT. WEAK
SIGNALS REMAIN FOR OVERALL FORCING PATTERN...THUS LIMITED POPS TO
LOW SLIGHTS.

VERY WARM DAY IN STORE TODAY GIVEN LL THERMAL FIELDS /H85 T/S
AROUND 30C/ WITH TRIPLE DIGITS EXPECTED OVER SCENTRAL SD...90S
ELSEWHERE. WEAK/STALLING SFC TROUGH WILL ALLOW SLIGHTLY COOLER
CONDS FRI...ALTHOUGH FAR SW AREAS WILL SEE THE WARMEST CONDS GIVEN
DEEPEST MIXING POTENTIAL. BUMPED OVERNIGHT LOWS UP TONIGHT AND
FRIDAY NIGHT GIVEN WARM THERMAL FIELDS AND GENERAL SW FLOW...THIS
IS ESP SO IN THE BLACK HILLS FOOTHILLS.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
ISSUED AT 224 AM MDT THU SEP 3 2015

UPPER LOW WILL CROSS THE NRN ROCKIES SAT AND INTO THE
ERN MT/WRN ND SUN. MODELS CONSISTENTLY SHOWING THE AREA MOSTLY
GETTING DRY SLOTTED THROUGH THE WEEKEND...SO EXPECTED QPF AMOUNTS
OVER THE CWA HAVE DECREASED. HAVE REDUCED POPS TO REFLECT THIS
TREND...ESPECIALLY SATURDAY. DID RAISE TEMPS SAT AS IT LOOKS LIKE
WARMER TEMPS WILL PUSH NWRD INTO THE REGION. COLD FRONT WILL CROSS
THE AREA SUN WITH COOLER TEMPS...SLIGHTLY BELOW AVG...PERSISTING
ACROSS THE REGION THROUGH MUCH OF NEXT WEEK. PERIODIC CHANCES OF
PRECIP POSSIBLE TOWARD THE MIDDLE OF THE WEEK AS UPPER WAVES PUSH
THROUGH ZONAL FLOW.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z FRIDAY
ISSUED AT 1105 AM MDT THU SEP 3 2015

ISOLATED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND
EVENING ACROSS THE AREA. MVFR CONDITIONS AND GUSTY WINDS ARE
POSSIBLE NEAR THESE STORMS. OTHERWISE VFR CONDITIONS EXPECTED
THROUGH THE PERIOD.

&&

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

$$

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



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