Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 092314
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
614 PM CDT WED JUL 9 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 350 PM CDT WED JUL 9 2014

SHORTWAVE DROPPING THROUGH IN NORTHWEST FLOW ACROSS CENTRAL SOUTH
DAKOTA LEADING TO A FEW SHOWERS AND THUNDERSTORMS ACROSS SOUTH
CENTRAL SOUTH DAKOTA.  IN GENERAL...THE BULK OF THE FORCING REMAINS
TO THE WEST OF THE FORECAST AREA...AND AS IT WORKS SOUTH AND
EAST...EXPECT ACTIVITY TO REMAIN SOUTHEAST OF THE FORECAST AREA.

AGREE WITH PREVIOUS FORECASTER THAT COULD SEE A THUNDERSTORM OR TWO
WITH MOISTURE RETURN LATER TONIGHT...THOUGH FOCUS WILL MAINLY BE
SOUTH.  HAVE INCREASED POPS AROUND SUNRISE IN SOUTH CENTRAL SOUTH
DAKOTA FOR THE THREAT FOR ELEVATED STORMS.  WHILE THE INSTABILITY IS
SOMEWHAT MEAGER IN THE 600-800 J/KG RANGE...SHEAR PROFILES AREN/T
THAT BAND AND COULD SEE AN ELEVATED HAILER OR TWO.

BETTER CHANCES FOR CONVECTION INCREASE THROUGHOUT THE DAY ON
THURSDAY WITH CONTINUED SOUTHERLY FLOW DRAWING MOISTURE INTO THE
REGION...AND A WEAK WAVE PASSING THROUGH THE AREA THROUGH THE
AFTERNOON HOURS.  HAVE KEPT SCATTERED COVERAGE IN THE GRIDS.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 350 PM CDT WED JUL 9 2014

A SMALL SEVERE WEATHER POTENTIAL WOULD APPEAR TO BE IN PLACE FOR
THURSDAY EVENING THROUGH THE MISSOURI VALLEY...ESPECIALLY THE
LOWER BRULE AREAS. WHILE LIKELY THAT NAM INSTABILITY/SHEAR FIELDS
ARE SOMEWHAT OVERDONE...PARAMETERS DO SUPPORT SOME LESSER
ORGANIZED SEVERE MODES GOING THROUGH THE EVENING. AS ANY SURFACE
BASED STORMS WHICH DEVELOP FURTHER WEST DURING THE LATE DAY
PROPAGATE INTO THE SOUTHWESTERN CWA...LIKELIHOOD OF BECOMING
ELEVATED RATHER THAN SURFACE BASED REALLY DIMINISHES THE EFFECTIVE
SHEAR FOR ELEVATED STORMS...WHICH APPEARS TO WEAKEN ENOUGH TO
REMOVE ANY APPRECIABLE SUPERCELL THREAT. COVERAGE OF STORMS SHOULD
INCREASE WITH LOW LEVEL JET THROUGH THE EVENING...WITH NOSE TOWARD
SOUTHEAST SOUTH DAKOTA AND SOUTHWEST MINNESOTA...WHERE HAVE
CONCENTRATED HIGHEST POPS...AND JUST TIMED A BIT LATER THAN
EARLIER FORECAST.

SYNOPTIC BASED COLD FRONT WILL BE WORKING SOUTHWARD ON FRIDAY...
BUT THE BIGGEST BITE IN TERMS OF PRECIPITATION THREAT WILL LIKELY
BE REMOVED WITH THE LEADING COLD FRONT/CONVECTIVE OUTFLOW WELL TO
THE SOUTH BY THE TIME THE MIDDAY HOURS ARE REACHED. SECONDARY
CONVERGENCE MOVING INTO THE NORTHERN HALF OF THE AREA INDICATED TO
BE FAIRLY STRONGLY CAPPED...AND WOULD HAVE TO MONITOR THIS AREA
FOR HIGHER MIXED LAYER THETA E TO PROMOTE RETURN OF THE SMALL
CHANCE POPS. POSSIBLE THAT SOME HIGHER PLAINS CONVECTION WOULD
WANDER TOWARD THE WESTERN CWA LATER IN THE NIGHT AND THROUGH
SATURDAY MORNING...WITH NAM JUST A BIT SLOWER ON EVOLUTION OF
FEATURES COMPARED TO OTHER MODELS. PROSPECT FOR PRECIPITATION
FRANKLY APPEAR TO BE A PRETTY LOW CHANCES FROM FRIDAY NIGHT
THROUGH SATURDAY.

THE MESSAGE GOING INTO NEXT WEEK WILL BE MUCH COOLER TEMPERATURES...
WITH THE COMPLETE MODEL SUITE INDICATING A FORMIDABLE UPPER TROUGH
TOWARD THE GREAT LAKES REGION...ENTRENCHING THE AREA IN A VERY
STRONG NORTHWEST FLOW ALOFT. HIGHS SHOULD BE 10 TO 15 DEGREES
BELOW NORMAL ON TUESDAY...AND ONLY MARGINALLY WARMER BY THURSDAY.
AFTER A BREAK FROM THE SMOKY CONDITIONS...THIS COULD THEN LEAD TO
ANOTHER PERIOD OF ENHANCED SMOKE TRANSPORT FROM NORTHERN CANADIAN
FIRES...PERHAPS WITH A MINOR IMPACT ON TEMPERATURES.  OTHERWISE...
MAIN WEAKLY CONVERGENT COLD FRONT EXPECTED TO SLIDE INTO THE AREA
LATER ON SUNDAY... WITH PERHAPS A COUPLE OF SHOWERS AND
THUNDERSTORMS FAVORING THE NORTHEASTERN HALF OF THE CWA. MAIN
BRUNT OF UPPER WAVE SHOULD BE FELT BY LATER ON MONDAY WITH
INCREASE IN COLD ADVECTION...LATE DAY CHANCE FOR THUNDERSTORMS
SHOULD ALMOST CERTAINLY BE SOUTH OF THE CWA...BUT KEPT IN A
BRIDGING SMALL THREAT THROUGH THE SOUTHERN TIER.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 610 PM CDT WED JUL 9 2014

VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. SOME SLIGHTLY
REDUCED VISIBILITIES IN SMOKE THROUGH THIS
EVENING...OTHERWISE...LIGHT EASTERLY TO SOUTHEASTERLY WINDS
OVERNIGHT WILL PICK UP AROUND 15Z ON THURSDAY.

&&

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

$$

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






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