Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 050839
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
339 AM CDT WED AUG 5 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 339 AM CDT WED AUG 5 2015

SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE OCCURRING VERY
EARLY THIS MORNING THROUGH OUR LOWER IOWA ZONES IN ASSOCIATION
WITH WEAK 850 MB THETA E ADVECTION. WILL SEE THIS ISOLATED
ACTIVITY CONTINUE THROUGH THE MORNING HOURS...THEN THERE SHOULD BE
A DOWNWARD TREND AS FORCING WEAKENS BY THE AFTERNOON AS AN UPPER
LEVEL SHORTWAVE LOCATED OVER SOUTH CENTRAL NEBRASKA CONTINUES TO
SLIDE OFF TO THE SOUTHEAST THROUGH THE DAY. IT WILL BE ANOTHER
SEASONABLY WARM DAY WITH HIGHS AROUND 80 CENTRAL AND EAST TO MID
80S THROUGH THE JAMES RIVER VALLEY.

TONIGHT WILL BE MAINLY DRY BETWEEN SYSTEMS...AND IT WILL BE A
MILD NIGHT WITH LOWS MID AND UPPER 60S. ANOTHER SHORTWAVE BEGINS
TO PUSH OUT OF THE NORTHERN ROCKIES LATE TONIGHT...AND WITH
INCREASING LOW LEVEL THETA E ADVECTION AND INSTABILITY THROUGH
WESTERN SOUTH DAKOTA THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER
THAT AREA OVERNIGHT. RELATED TO THAT...CANNOT COMPLETELY RULE OUT
THAT ISOLATED THUNDERSTORMS WILL GRAZE OUR FAR WESTERN CWA TOWARD
12Z ON THURSDAY.


.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 339 AM CDT WED AUG 5 2015

THURSDAY STILL LOOKS TO BE FAIRLY ACTIVE...THOUGH TIMING OF
DEVELOPMENT A LITTLE UNCERTAIN. COULD SEE SOME EARLY MORNING
ACTIVITY IN FAR NORTHERN CWA AS DEVELOPING ELEVATED WARM FRONT
MOVES THROUGH...AND WILL CARRY SOME LOW MORNING POPS WITH THIS IN
MIND. THINK MAIN FOCUS WILL BE IN THE AFTERNOON/EVENING THOUGH...
AS A FAIRLY STRONG MID-UPPER LEVEL WAVE MOVES ACROSS THE REGION.
MOST MODELS CONSISTENT IN DEVELOPING SURFACE LOW IN NORTHEAST SD
BY LATE THURSDAY...WITH COLD FRONT EXTENDING SOUTHWARD INTO THE
WESTERN PART OF OUR FORECAST AREA BY 07/00Z. GREATER QUESTIONS ON
EXACT PLACEMENT OF WARM FRONT...THOUGH LOOKS TO BE NEAR THE
NORTHEAST FRINGE OF THE FORECAST AREA BY LATE AFTERNOON. OF
COURSE...BOUNDARIES FROM ANY EARLY-DAY CONVECTION WOULD LIKELY
IMPACT AFTERNOON DEVELOPMENT AS WELL. WITH APPROACHING WAVE...DEEP
LAYER SHEAR REACHES 35-45KT WITH MOST MODELS DEPICTING INSTABILITY
IN THE 1500-2500J/KG RANGE. THIS SUFFICIENT FOR ISOLATED-SCATTERED
SEVERE STORMS...AND WILL CONTINUE MENTION OF THIS IN THE HWO.

TIMING OF THE WAVE SHOULD BRING AN END TO ACTIVITY IN OUR AREA BY
06Z OR SO...WITH QUIET CONDITIONS THEN RETURNING THROUGH THE DAY
FRIDAY AS WEAK UPPER RIDGE MOVES ACROSS THE REGION. TEMPERATURES
SHOULD BE A DEGREE OR TWO EITHER SIDE OF SEASONAL NORMALS...THOUGH
AGAIN EARLY-DAY CONVECTION/LINGERING CLOUD COVER THURSDAY COULD
IMPACT HIGHS THAT DAY...ESPECIALLY IN NORTHEAST PARTS OF THE AREA.

LONGER RANGE SATURDAY THROUGH TUESDAY WILL BEGIN IN AN UNSETTLED
PATTERN...AS SERIES OF WAVES MOVE AROUND A DOMINANT SOUTHERN PLAINS
RIDGE. INSTABILITY NOT MUCH TO WRITE HOME ABOUT...INCREASING SOME
DURING THE LATTER HALF OF THE WEEKEND AS TEMPERATURES ALOFT COOL
WITH THE PASSING WAVE. STILL A FAIR AMOUNT OF UNCERTAINTY IN TIMING
WAVES AND ASSOCIATED BETTER PRECIP CHANCES THROUGH THE WEEKEND...
THOUGH LOOKING LIKE SUNDAY MAY BE THE BETTER/DRIER DAY OF THE
WEEKEND FOR MOST AREAS.

TEMPERATURES REMAIN ON THE COOLER SIDE OF NORMAL FOR THE WEEKEND
AND INTO MONDAY...WITH DRY WEATHER/WARMER TEMPERATURES BEGINNING
TO RETURN TO THE REGION BY TUESDAY AS UPPER RIDGE MAKES A STRONGER
PUSH AT BUILDING NORTHWARD INTO THE REGION.


&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1106 PM CDT TUE AUG 4 2015

BAND OF SCATTERED SHOWERS AND ISOLATED THUNDER WILL HOVER AROUND
THE KSUX AREA THROUGH THE EARLY MORNING. EVEN IN RAINFALL...
CONDITIONS WILL LIKELY REMAIN VFR...AND THUNDER POTENTIAL IS
SMALL ENOUGH AT A SITE TO KEEP CLEAR OF THE TAF FOR NOW. MAY ALSO
FIND A BRIEF PERIOD OF MVFR VISIBILITY AROUND KSUX IN THE EARLY
MORNING HOURS...BUT AGAIN WITH ABUNDANCE OF HIGHER CLOUDS AND
LIGHT EASTERLY WINDS...HAVE KEPT OUT OF THE TAFS ON BASIS OF
PROBABILITY.


&&

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

$$

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



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