Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 312203
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
403 PM MDT MON AUG 31 2015

.SHORT TERM...THIS EVENING THROUGH TUESDAY NIGHT
ISSUED AT 205 PM MDT MON AUG 31 2015

MAIN UPPER WAVE IS MOVING THROUGH MANITOBA...WITH ANOTHER WEAK
SHORTWAVE APPROACHING FROM THE WEST. SURFACE MAP SHOWS HIGH
PRESSURE PUSHING INTO THE CWA. RADAR INDICATES A BAND OF VERY
LIGHT SHOWERS CONTINUING TO TRACK EASTWARD THROUGH CENTRAL SD.
UNDER PARTLY TO MOSTLY CLOUDY SKIES...WINDS ARE GENERALLY
NORTHERLY AROUND 10 KTS...AND TEMPS ARE IN THE 70S.

WEAK UPPER FORCING AND SOME 850-700 MB FRONTOGENESIS MAY ALLOW
SHOWERS TO CONTINUE OVER SOUTH CENTRAL SD TONIGHT. A LITTLE
INSTABILITY COULD SUPPORT SOME WEAK STORMS AS WELL. LOWS TONIGHT
WILL BE IN THE 50S TO LOWER 60S.

WITH SURFACE HIGH EAST OF THE AREA ON TUESDAY...RETURN FLOW WILL SET
UP ACROSS THE SD PLAINS...BRINGING IN MOISTURE AND VERY WARM AIR.
MEANWHILE WESTERLY WINDS ACROSS NORTHEASTERN WYOMING WILL ADVECT IN
WARM AND DRY AIR THERE. HIGHS WILL BE IN THE 90S...WITH DEW POINTS
RANGING FROM THE 30S ACROSS NORTHEASTERN WYOMING TO THE LOWER 60S
ACROSS SOUTH CENTRAL SD. NO PRECIP IS EXPECTED FOR TUESDAY.

.LONG TERM...WEDNESDAY THROUGH MONDAY
ISSUED AT 205 PM MDT MON AUG 31 2015

ON WEDNESDAY THE MODELS AGREE WELL THAT A BROAD AREA OF
UPPER-LEVEL HIGH PRESSURE WILL COVER THE SERN CONUS WHILE AN UPPER
LOW IS OVER SWRN CANADA. THE UPPER LOW WILL SHIFT SLOWLY SOUTHEAST
INTO THE WRN CONUS BY SATURDAY...WITH A RIDGE OVER THE ERN CONUS.
THIS WILL KEEP THE CWA UNDER SWLY FLOW ALOFT...LEADING TO VERY WARM
AND DRY CONDITIONS THROUGH THURSDAY...WITH INCREASING CHANCES OF
SHRA/TSRA LATE IN THE WEEK AS THE STRONGER UPPER-LEVEL FLOW MOVES
EAST AND BRINGS BETTER CHANCES OF SHORT-WAVE TROUGHS THAT WILL
AFFECT THE CWA. THE MAIN PUSH OF COOLER AIR SHOULD COME SATURDAY
THROUGH SUNDAY. THE ECMWF IS MUCH SLOWER THAN THE GFS IN EJECTING
THE UPPER LOW ACROSS THE NRN PLAINS SUNDAY THROUGH MONDAY...WHICH
SEEMS REASONABLE GIVEN THE TYPICAL FAST BIAS OF THE GFS WITH MOVING
UPPER LOWS OUT OF THE WEST. THUS...EXPECT SCT SHRA/TSRA TO LINGER
THROUGH THE WEEKEND.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 400 PM MDT MON AUG 31 2015

VFR CONDITIONS EXPECTED THROUGH THE PERIOD. LIGHT HIGH BASED -SHRA
EXPECTED AT TIMES ACRS SCNTRL SD.

&&

.FIRE WEATHER...
ISSUED AT 205 PM MDT MON AUG 31 2015
DRY AND BREEZY CONDITIONS WILL DEVELOP ACROSS PARTS OF NERN WY
WEDNESDAY AHEAD OF A DEEPENING LOW PRESSURE OVER MT. DEWPOINTS
SHOULD DROP TO AROUND 40F WITH RH DROPPING TO 10-15 PERCENT. NAM
FORECAST SOUNDINGS INDICATE WINDS OF 25-30KT MIXING DOWN FROM
ALOFT. THUS...HAVE ISSUED A FIRE WEATHER WATCH FOR SRN CAMPBELL
COUNTY.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...FIRE WEATHER WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY
     EVENING FOR WYZ259.

&&

$$

SHORT TERM...POJORLIE
LONG TERM...BUNKERS
AVIATION...JOHNSON
FIRE WEATHER...BUNKERS


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