Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 281957
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
257 PM CDT THU MAY 28 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 257 PM CDT THU MAY 28 2015

MESSY FORECAST THROUGH FRIDAY AS A COUPLE OF SHORTWAVES AND A
FRONTAL BOUNDARY MOVE THROUGH THE REGION DURING THIS TIME FRAME.
PRESENTLY SEEING AN UPPER LEVEL SHORTWAVE LIFTING THROUGH EASTERN
NEBRASKA...TRIGGERING A FEW SHOWERS IN OUR FAR SOUTHERN IOWA ZONES.
THIS FEATURE WILL LIFT INTO CENTRAL IOWA THIS EVENING...BRINGING
THUNDERSTORM CHANCES TO OUR NORTHWESTERN IOWA ZONES AND PORTIONS OF
OUR MINNESOTA ZONES. DID LOWER POPS A BIT OVER THIS AREA FROM
PREVIOUS FORECAST AS MODELS ARE TAKING THE SHORTWAVE A LITTLE
FARTHER TO THE EAST THAN PREVIOUSLY. OTHERWISE...A COLD FRONT IS
LOCATED THROUGH WESTERN SOUTH DAKOTA. THIS SYSTEM WILL PUSH INTO THE
WESTERN PORTIONS OF OUR CWA DURING THE OVERNIGHT HOURS...TRIGGERING
SHOWERS AND THUNDERSTORMS OVER THAT AREA. LATE AFTERNOON CAPE VALUES
WILL BE HOVERING AROUND 1000 J/KG OVER THAT AREA...THOUGH SHEAR IS
WEAK. IF ACTIVITY WERE TO DEVELOP BY LATE AFTERNOON CAN NOT RULE OUT
SMALL HAIL...AND GUSTY WINDS WITH DRY AIR ALOFT.
OTHERWISE...INSTABILITY QUICKLY WANES IN THE EVENING. IT WILL BE A
MILD NIGHT ACROSS THE AREA WITH LOWS IN THE UPPER 50S TO LOWER 60S.

ON FRIDAY MODELS ARE IN PRETTY DECENT AGREEMENT ON MOVING THE
SURFACE FRONT THROUGH ALMOST THE ENTIRE CWA BY 18Z. MODELS ARE STILL
NOT IN THE BEST AGREEMENT ON THE HANDLING OF SHORTWAVES MOVING
THROUGH THE REGION ON FRIDAY...THOUGH THE CONSENSUS THEME IS FOR
INCREASING SHOWER AND THUNDERSTORM CHANCES THROUGH THE
MORNING...BECOMING LIKELY IN THE EAST BY EARLY AFTERNOON AS THE
SHORTWAVE INTERACTS WITH THE ELEVATED FRONT SHIFTING SOUTHWARD
ACROSS THE AREA. AS THE FRONT CONTINUES TO PUSH SOUTHWARD THROUGH
THE MID AND LATE AFTERNOON THE BETTER RAINFALL CHANCES WILL
GRADUALLY SHIFT TO THE SOUTH AND EAST. BECAUSE OF THE TIMING OF THE
FRONTAL PASSAGE THE BETTER INSTABILITY WILL BE TO THE SOUTH OF OUR
CWA IN THE AFTERNOON...SO NOT EXPECTING ANY SEVERE STORMS. THERE
WILL BE A FAIRLY WIDE RANGE OF TEMPERATURES ACROSS THE CWA ON FRIDAY
WITH COLD AIR ADVECTION BEHIND THE FRONT...WITH HIGHS IN THE LOWER
60S IN THE FAR NORTH AND WEST TO MID 70S THROUGH THE SIOUX CITY TO
STORM LAKE CORRIDOR.


.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 257 PM CDT THU MAY 28 2015

LINGERING SHOWERS OVER THE SOUTHEAST CORNER OF THE AREA WILL BE
QUICK TO MOVE OUT FRIDAY EVENING AND CLEARING WILL SPREAD THROUGHOUT
THE AREA DURING THE NIGHT. THIS WILL BRING A SETUP FOR A GENERALLY
DRY WEEKEND WITH COOL TEMPERATURES...60S HIGHS...BEGINNING TO WARM
FROM THE WEST SUNDAY.

THE GENERALLY DRY TERMINOLOGY REFERS TO A LITTLE INCREASE IN
DYNAMIC LIFT AND THERMAL SUPPORT STARTING TO DEVELOP INTO THE
NORTHERN PART OF THE AREA BY SUNDAY AFTERNOON. AT THIS TIME EXPECT
THE AIR TO BE TOO DRY TO SUPPORT MENTION OF EVEN SPOTTY SHOWERS OR
STORMS UNTIL SUNDAY NIGHT.

WINDS WILL BE FAIRLY LIGHT SATURDAY...THOUGH NOT QUITE GOING TO AN
EVENING CALM AS THE SURFACE HIGH CENTER STAYS NORTH OF THE AREA. A
SOUTHEASTERLY LOW LEVEL FLOW WILL BEGIN TO INCREASE FROM THE WEST
SUNDAY.

SUNDAY NIGHT THROUGH THURSDAY WILL BRING A RETURN TO THUNDERSTORM
MENTION...BUT SLOWLY THROUGH AT LEAST TUESDAY...AS PLAINS RIDGING
LIMITS DYNAMIC SUPPORT AND SHEAR AND THERMAL SUPPORT. TEMPERATURES
WILL BE WARMING AND MOISTURE AND INSTABILITY WILL BE SLOWLY
INCREASING THROUGH TUESDAY. FOR WEDNESDAY AND THURSDAY...THE
APPROACHING PACIFIC TROUGH WILL TURN THE UPPER FLOW SOUTHWESTERLY
AND MOISTURE WILL CONTINUE TO INCREASE. SUPPORT WILL EXIST FOR
INCREASING SHOWER AND THUNDERSTORM COVERAGE. DAYTIME TEMPERATURES
WILL HALT THEIR WARMING TREND WITH MORE CLOUDS AND THE RAIN
THREAT...THOUGH NIGHTTIME LOWS WILL WARM A LITTLE MORE.


&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1214 PM CDT THU MAY 28 2015

KHON OBSERVATION IS OUT...BUT IS STILL REPORTING ALTIMETER
READING. WITH LIMITED OBSERVATIONS...AMENDMENT(S) ARE NOT
SCHEDULED UNTIL OBSERVATION RETURNS.

GUSTY SOUTHERLY WINDS WILL DIMINISH EARLY THIS EVENING...WITH
THUNDERSTORMS DEVELOPING THROUGH THE WEST IN THE LATE EVENING AS A
COLD FRONT PUSHES INTO THE AREA. THUNDERSTORM CHANCES SHOULD HOLD
OFF AT KFSD AND KSUX UNTIL VERY LATE TONIGHT OR EARLY FRIDAY
MORNING...THOUGH CONFIDENCE IN EXACT TIMING REMAINS FAIRLY LOW.
WINDS WILL GRADUALLY TRANSITION TO NORTHERLY ON FRIDAY AS THE
FRONT MOVES ACROSS THE AREA.


&&

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

$$

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



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