Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 042301
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
501 PM MDT FRI SEP 4 2015

.SHORT TERM...THIS EVENING THROUGH SATURDAY NIGHT
ISSUED AT 142 PM MDT FRI SEP 4 2015

19Z SURFACE ANALYSIS HAD LOW OVER CENTRAL SD WITH FRONTAL
BOUNDARY FROM NORTHEAST ND TO THE BLACK HILLS TO CENTRAL WY WITH A
TROUGH INTO WESTERN KS. EARLY MORNING SHORTWAVE NORTHEAST OF AREA
WITH 80KT JET STREAK/SHORTWAVE ENERGY OVER WESTERN CO HEADING
NORTHEAST INTO SOUTHEAST WY. THIS ACTIVITY WILL ROLL INTO THE CWA
LATE THIS AFTERNOON/EARLY EVENING AND SLOWLY MOVE NORTHEAST
OVERNIGHT...WHICH IS IN GOOD AGREEMENT WITH MOST FORECAST MODEL
GUIDANCE. TEMPERATURES WILL BE WARMER THAN GUIDANCE IN THE EAST
AND NEAR TO THE WEST.

SATURDAY...UPPER TROUGH NOW OVER THE NORTHWEST US WILL SPILL INTO
ROCKIES AND INTO LIFT INTO MT. FRONTAL BOUNDARIES WILL REMAIN IN
PLACE...AND PERHAPS MOVE A BIT TO THE NORTHWEST/WEST DURING THE DAY
WITH RETURN FLOW AHEAD OF PRESSURE FALLS ASSOCIATED WITH TROUGH. 1-
2KJ/KG MLCAPE POOLS NEAR THE MT/SD/WY/ND BORDER AREA OF THE CWA WITH
MLCIN GONE IN THE AFTERNOON. 15-20M/S 0-6KM BULK SHEAR AVAILABLE.
POTENTIAL EXISTS FOR ISOLATED SUPERCELLS...BUT IMPLIED SUBSIDENCE
BEHIND TONIGHT/S SHORTWAVE AND ANY DEBRIS CLOUDS COULD INTERFERE
WITH PEAK DAYTIME HEATING WITH MAIN SYNOPTIC FORCING HEADING NORTH
OF THE CWA SATURDAY NIGHT...ALONG WITH A GOOD DRY SLOT. WILL
MENTION ISOLATED T+ IN THE FAR NORTHWEST FOR NOW. COLD FRONT WILL
ENTER FAR NORTHWEST REACHES OF THE CWA LATE SATURDAY NIGHT.
TEMPERATURES WILL BE NEAR GUIDANCE IN THE WEST AND ABOVE IN THE
EAST.

.LONG TERM...SUNDAY THROUGH FRIDAY
ISSUED AT 142 PM MDT FRI SEP 4 2015

MEDIUM RANGE MODELS STILL IN VERY GOOD AGREEMENT ON UPPER LOW
PASSING TO THE NORTH AND WEST OF THE AREA ON SUNDAY. COOLER AIR
WILL PUSH INTO THE AREA BEHIND PASSING COLD FRONT...WITH BRISK
WEST TO NORTHWEST WINDS. HIGH TEMPERATURES WILL RANGE FROM AROUND
70 IN NW SD...TO NEAR 90 IN FAR SOUTH CENTRAL SD.

ON MONDAY...ZONAL FLOW WILL DEVELOP FOR THE EARLY PART OF NEXT
WEEK...TRANSITIONING TO NORTHWESTERLY FLOW FOR THE LATTER PART OF
THE WEEK. THIS SHOULD RESULT IN SEASONABLY WARM AND MOSTLY DRY
CONDITIONS FOR MUCH OF THE WEEK. WEAK WARM AIR ADVECTION COMBINED
WITH AND UPPER SHORTWAVE MAY PRODUCE A FEW SHOWERS AND STORMS
ACROSS THE SOUTH DAKOTA PLAINS ON MONDAY AND MONDAY NIGHT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 500 PM MDT FRI SEP 4 2015

MAINLY VFR CONDITIONS EXPECTED NEXT 24 HOURS. ISOLD/SCT HIGH BASED
-TSRA POSSIBLE TONIGHT AS ANOTHER DISTURBANCE MOVES THROUGH.

&&

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

$$

SHORT TERM...HELGESON
LONG TERM...15
AVIATION...JOHNSON


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