Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 211711
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1211 PM CDT THU MAY 21 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 312 AM CDT THU MAY 21 2015

VERY NICE DAY ON TAP ACROSS THE AREA...ALTHOUGH A BIT ON THE
BREEZY SIDE ACROSS THE NORTHEAST HALF OF THE CWA WHERE TIGHTER
GRADIENT LINGERS INTO THE EARLY-MID AFTERNOON. SUNSHINE SHOULD BE
PREVALENT MOST OF THE DAY...THOUGH SCATTERED CU EXPECTED TO FORM
NEAR A WEAK BACKDOOR FRONT WHICH DROPS THROUGH THE NORTHEAST HALF
OF THE AREA THIS AFTERNOON. WITH THE SUNSHINE AND DECENT
MIXING...WILL FAVOR THE WARMER END OF MODEL GUIDANCE WITH
TEMPERATURES EXPECTED TO REACH THE LOWER 70S MOST AREAS.

SURFACE RIDGE WEST OF THE JAMES RIVER EARLY THIS EVENING WILL DRIFT
EASTWARD ACROSS THE FORECAST AREA TONIGHT. THIS WILL BRING MOSTLY
CLEAR SKIES AND QUICKLY DECREASING WINDS...ALLOWING TEMPERATURES TO
DROP OFF FAIRLY RAPIDLY THIS EVENING. WITH DRY AIR MASS IN PLACE...
HEDGED A LITTLE MORE TOWARD THE LOWER END OF MODEL GUIDANCE FOR LOW
TEMPERATURES TONIGHT...WITH READINGS IN THE LOWER-MID 40S.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 312 AM CDT THU MAY 21 2015

DEVELOPING WARM ADVECTION PATTERN SHOULD BRING DECENT MOISTURE
ADVECTION AT LOW AND MID LEVELS LATE FRIDAY THROUGH THE WEEKEND. A
COOL BAND AT H8 AHEAD OF WEEKEND PLAINS RIDGING WILL HELP KEEP
INSTABILITY TAME FOR A WHILE...BUT THERE LOOKS LIKE ENOUGH LIFT
DEVELOPING AT MID LEVELS FOR AN INCREASE IN SHOWERS FROM THE
SOUTHWEST STARTING LATE FRIDAY. EVENTUALLY...IT LOOKS LIKE ENOUGH
INSTABILITY WILL SPREAD IN AS MAIN WESTERN SYSTEM APPROACHES FOR
SOME THUNDER...AND FAVOR THE GFS AND EC OVER THE NAM ON THIS WITH
THE NAM LOOKING TOO SLOW ON DEVELOPING THE FLOW AHEAD OF THE MAIN
SYSTEM WHICH SHOULD BE CLOSE TO THE WEST ON SUNDAY.

FRIDAY WILL BE A DAY OF CLOUDS INCREASING FROM THE SOUTHWEST WITH A
SHOWER CHANCE LATE FAR SOUTHWEST. TEMPERATURES FRIDAY WILL REACH THE
LOWER 70S EXCEPT 60S SOUTHWEST UNDER THE THICKENING CLOUDS.

ONE THING LOOKS CLEAR CUT FROM ALL MODEL SOLUTIONS...ACTUALLY CALL
IT CLOUDY CUT...AND THAT IS THE COPIOUS LOW LEVEL MOISTURE
INCREASE...SO DO NOT EXPECT TO SEE THE SUN THIS WEEKEND REGARDLESS
OF CONVECTIVE DEVELOPMENT OR LACK THEREOF. THE CLOUDS WILL HOLD DOWN
THE DIURNAL RANGE WITH A LOT OF 60S TO LOW 70S HIGHS AND 50S LOWS.

FOR MUCH OF NEXT WEEK ON CURRENT MODEL SOLUTIONS...WAVES FROM A
DECAYING MAIN SYSTEM WILL CONTINUE TO BE EJECTED OVER THE AREA AND
KEEP A CHANCE OF SHOWERS AND/OR STORMS IN THE PICTURE. AS THE FLOW
TURNS BACK MORE WEST SOUTHWESTERLY...THE LOWEST LEVELS SHOULD DRY
SOME...SUNSHINE SHOULD PARTIALLY RETURN...AND DAYTIME TEMPERATURES
WOULD WARM SOME...LIKE INTO THE 70S. THE GENERAL PATTERN LOOKS
SOMEWHAT CERTAIN...BUT THE DETAILS ON PRECIPITATION TIMING
LOON IMPOSSIBLE TO PIN DOWN...SO THERE WILL BE NO DAY IN THE
EXTENDED PERIOD WITHOUT PRECIPITATION MENTION.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1209 PM CDT THU MAY 21 2015

VFR CONDITIONS THROUGH THE TAF PERIOD. GUSTY NORTHWEST WINDS THIS
AFTERNOON WILL QUICKLY DIMINISH THIS EVENING.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...JH
LONG TERM...
AVIATION...JM



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