Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 302309
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
609 PM CDT THU APR 30 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 312 PM CDT THU APR 30 2015

SURFACE BOUNDARY NEARING CENTRAL SD AT 20Z WILL PROGRESS SLOWLY EAST
OVER THE FORECAST AREA THROUGH THE NEXT 24 HOURS. INITIALLY RUNNING
INTO VERY DRY AIR MASS ACROSS EASTERN SD AND POINTS EASTWARD...SO
THINK ANY PRECIP THREAT FOR OUR AREA WILL BEGIN AS HIGH BASED
SHOWERS WITH MAYBE AN ISOLATED THUNDER THREAT IN OUR FAR WEST THIS
EVENING. AS THE BOUNDARY CONTINUES EAST...INCREASING LOW LEVEL JET
AHEAD OF THE BOUNDARY COULD BRING SOME INCREASE IN MOISTURE FOR THE
SYSTEM TO WORK WITH. THIS SHOULD LEAD TO SOME DEVELOPMENT/INCREASE
IN COVERAGE OF MAINLY SHOWERS AHEAD OF THE BOUNDARY AS IT MOVES EAST
OF THE JAMES RIVER VALLEY LATE TONIGHT...THEN CONTINUES INTO MN/IA
FRIDAY MORNING. SHOWERS COULD LINGER OVER THE FAR SOUTHEAST INTO
FRIDAY AFTERNOON AS THE BOUNDARY PROGRESS SLOWS...BUT SUPPORT FOR
PRECIPITATION ALSO WANING...SO EXPECT GRADUAL DECREASE IN POPS OVER
NORTHWEST IA THROUGH THE AFTERNOON. INSTABILITY REALLY QUITE LIMITED
WITH THIS SYSTEM...SO ONLY AN ISOLATED THUNDER MENTION DURING THIS
EVENING...AND AGAIN FOR ANY LINGERING LATE MORNING/AFTERNOON SHOWERS
ACROSS OUR SOUTHEAST ON FRIDAY. STILL EXPECT RAINFALL AMOUNTS TO BE
ON THE LIGHTER SIDE...GENERALLY LESS THAN A TENTH OF AN INCH WEST OF
I-29...WITH A TENTH OR TWO POSSIBLE FOR OUR MN/IA COUNTIES.

SOUTHERLY FLOW TONIGHT WILL HOLD TEMPERATURES UP IN THE UPPER 40S TO
LOWER 50S...WITH MIXY NORTHWEST FLOW BEHIND THE BOUNDARY HELPING
AFTERNOON TEMPERATURES AGAIN CLIMB INTO THE 70S FOR MOST OF THE
AREA.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 312 PM CDT THU APR 30 2015

FRIDAY NIGHT AND SATURDAY MORNING SHOULD BE DRY. A THREAT OF
THUNDERSTORMS WILL THEN DEVELOP SLOWLY FROM THE WEST LATE SATURDAY
THROUGH SUNDAY MORNING AS A COLD FRONT DRAGGED EAST BY A CANADIAN
BORDER SHORT WAVE APPROACHES THE AREA. A STEADY BUT SLOW MOISTURE
AND INSTABILITY INCREASE FROM THE SOUTH WILL DEVELOP...AND PEAK
SUNDAY AFTERNOON INTO THE EARLY EVENING. THIS WILL COINCIDE WITH THE
ARRIVAL OF THE FRONT OVER THE SOUTHEAST PART OF THE FORECAST AREA
AND THIS FRONT WILL PROVIDE A STRONG FOCUS FOR STORMS TO DEVELOP.
WIND FIELDS LOOK FAIRLY WEAK THOUGH THERE ARE SOME FAVORABLE
DIRECTIONAL FACTORS. THE COMBINATION OF INCREASING INSTABILITY
MOISTURE AND HEATING WILL LIKELY CAUSE SOME SEVERE STORMS TO DEVELOP
WITH LARGE HAIL THE MAIN THREAT. THIS SEVERE THREAT WILL START FROM
SOUTHEAST SD INTO PART OF SOUTHWEST MN AND BECOME FOCUSED OVER
NORTHWEST IA DURING THE EARLY EVENING. STILL THREE DAYS AWAY SO SOME
CHANGES ARE POSSIBLE...THOUGH MODELS ARE BEING FAIRLY CONSISTENT ON
THIS FEATURE INCLUDING THE TIMING OF IT.

TEMPERATURES SHOULD WARM PRETTY WELL THIS WEEKEND WITH PLENTY OF
LOW TO MID 80S FOR HIGHS SATURDAY AND SUNDAY.

THUNDERSTORM THREAT MONDAY AND TUESDAY...LOOKING TO BE MAINLY OVER
THE SOUTHERN PART OF OUR AREA...WILL DEPEND ON HOW FAR SOUTH THE
POOLED MOISTURE AND INSTABILITY IS DRIVEN. CURRENT THINKING REMAINS
TO KEEPING A CHANCE AT LEAST SOUTH. TEMPERATURES WILL BE LESS WARM.

MODELS ARE STILL CONSISTENTLY SHOWING A POTENTIALLY WET PERIOD
WEDNESDAY AND THURSDAY AS UPPER LOW COMING ONTO NORTHERN BAJA COAST
LATE THIS WEEKEND IS EJECTED NORTHEAST BY ARRIVING LARGE PACIFIC
NORTHWEST UPPER LOW. SHOWERS AND STORMS WILL LIKELY BE NUMEROUS AND
THE EXTENDED GUIDANCE LIKELY POPS SEEM APPROPRIATE FOR THESE LAST
TWO DAYS OF THE FORECAST. TEMPERATURES WILL WARM SOME BUT DAYTIME
WARMING WILL LIKELY BE LIMITED BY COPIOUS CLOUD COVER.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 606 PM CDT THU APR 30 2015

VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. A FRONTAL
BOUNDARY WILL PUSH ACROSS THE AREA LATE TONIGHT INTO FRIDAY. THIS
SYSTEM MAY TRIGGER SCATTERED SHOWERS AS IT MOVES ACROSS THE
AREA...THOUGH SHOULD HAVE LITTLE IMPACT TO VISIBILITY. WINDS WILL
BECOME NORTHWESTERLY BEHIND THE FRONT.

&&

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

$$

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



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