Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 252026
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
226 PM MDT FRI JUL 25 2014

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 224 PM MDT FRI JUL 25 2014

WEAK SFC RIDGE OVER THE REGION IS SUPPORTING CLEAR
SKIES AND DRIER AIR INTO THE AREA. POTENT NORTHERN STREAM CLOSED
UPPER LOW WILL CONTINUE TO SLOWLY ADVECT/PROPAGATE SE THROUGH THE
PERIOD...WITH UPPER LEVEL FLOW GRADUALLY VEERING NW. NORTHERN STREAM
CLOSED UPPER VORTEX WILL SLOWLY SHIFT SE TONIGHT AND PARTIALLY PHASE
WITH A WEAK IMPULSE ROTATING AROUND THE NORTHERN PERIPHERY OF THE SW
CONUS UPPER LEVEL RIDGE...SUPPORTING CHANCES FOR SHRA/TS MAINLY OVER
SCENTRAL SD. SECONDARY COLD FRONT WILL PUSH SE ACROSS THE FA SAT
MORNING AS A  REFLECTED SFC LOW PUSHES INT THE GREAT LAKES.
CAA/PRESSURE RISES/AND STRONG LL FLOW WITH DEEP MIXING WILL SUPPORT
A BREEZY DAY SAT...WITH COOLER CONDITIONS EXPECTED...ESP ACROSS THE
NW HALF AS ANOTHER SFC RIDGE BUILDS INTO THE REGION.

TONIGHT...REFLECTED LL POS THETA-E ADV PER VEERING LL FLOW WILL
SUPPORT CHANCES FOR SHRA/TS ACROSS MUCH OF THE SE HALF...ESP LATE
TONIGHT. ALTHOUGH LIFT FROM PASSING IMPULSE WILL BE FAIRLY
WEAK...JET DYNAMIC FORCING FROM A PASSING JET STREAK SHOULD BE
ENOUGH TO COMPENSATE FOR THIS...ESP IN THE FAR SE. RETAINED A POP
MENTION...HIGHEST OVER TRIPP COUNTY. MUCAPE VALUES AOA 1500 J/KG IN
THE FAR SE COUPLED WITH STEEP MID LEVEL LAPSE RATES AND AMPLE
EFFECTIVE SHEAR MAY BE ENOUGH TO SUPPORT A ROTATING STORM OR
TWO...ESP CLOSER TO DAWN WHEN THE BEST OVERLAP OF FORCING WILL BE IN
PLACE...THE TIMING OF WHICH HAS BEEN PUSHED BACK IN LATEST GUIDANCE
OUTPUT. HENCE...HAVE TRENDED HIGHER POPS AFTER 12Z IN THE FAR
SE...WITH A DOWNTREND LATE MORNING.

SAT...LINGERING ACTIVITY SHOULD WANE BY LATE MORNING IN THE SE.
HOWEVER...LATEST NAM/NMM GUIDANCE SUGGEST THAT A FEW STORMS COULD
LINGER INTO EARLY AFTERNOON EXTREME SE. FOR NOW HAVE LEFT THE
AFTERNOON DRY THERE. SECONDARY COLD FRONT WILL PUSH THROUGH THE AREA
WITH WEAK CAA ENSUING...ESP THE NW. DEEP MIXING PER CLEAR SKIES AND
DECENT PGF ACROSS THE REGION WILL SUPPORT BREEZY CONDITIONS ON THE
SD PLAINS...ESP THE NW PORTION. A WIND ADV MAY BE NEEDED THERE IF
CURRENT TRENDS CONTINUE. SLIGHTLY COOLER CONDITIONS EXPECTED
SAT...MAINLY NW AREAS. COOL CONDITIONS FORECAST SAT NIGHT WITH DRIER
AIR/CLEAR SKIES/AND SLACKENING WINDS SUPPORTING DECENT RADIATIONAL
COOLING...ESP NW HALF. HAVE LOWERED MINS SOME.

&&

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 224 PM MDT FRI JUL 25 2014

UPPER RIDGING WILL DOMINATE ACROSS THE WRN CONUS THROUGH THE
EXTENDED. WITH THE MAIN AXIS REMAINING WEST OF THE REGION...OVERALL
NW FLOW ALOFT IS EXPECTED WITH A FEW WEAK WAVES CROSSING THROUGH.
THIS COULD BRING SLIGHT CHANCES OF STORMS PERIODICALLY...BUT OVERALL
A DRY EXTENDED PERIOD IS EXPECTED. TEMPERATURES WILL BE NEAR AVERAGE.

&&

.AVIATION...FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING
ISSUED AT 224 PM MDT FRI JUL 25 2014

ISOLATED TO SCATTERED STORMS ARE POSSIBLE TONIGHT OVER CENTRAL SOUTH
DAKOTA. OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST
PERIOD.

&&

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

$$

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






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