Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 231715
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1215 PM CDT TUE SEP 23 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 359 AM CDT TUE SEP 23 2014

AS OF 4 AM SHOWERS STILL MAINLY CONFINED TO AROUND THE MISSOURI
RIVER...WITH DRY AIR TO THE NORTHEAST SLOWING ITS MOVEMENT. FORCING
WILL CONTINUE TO INCREASE ACROSS THE AREA THIS MORNING AS THE UPPER
LOW CURRENTLY OVER THE BLACK HILLS MOVES EAST. THIS COMBINED WITH
CONVERGENCE ALONG THE LOW LEVEL JET STILL SUPPORTS A PERIOD OF DEEP
LIFT OVER THE AREA...WHICH COMBINED WITH THE INCREASING MOISTURE
WILL RESULT IN SCATTERED TO NUMEROUS SHOWERS. DID SLOW DOWN TIMING
OF THE NORTHEAST PROGRESSION OF THESE SHOWERS GIVEN CURRENT RADAR
TRENDS...WITH THE HRRR SEEMING CLOSEST TO REALITY. GREATEST COVERAGE
AND HIGHEST INTENSITY OF THE SHOWERS SHOULD STAY SOUTH OF INTERSTATE
90 CLOSER TO THE BETTER LOWER LEVEL CONVERGENCE...BUT STILL EXPECT
SHOWERS TO EVENTUALLY MAKE IT INTO THE WHOLE AREA. THE SHOWER THREAT
WILL DECREASE AS THE FORCING PUSHES EAST THIS AFTERNOON...AND
SUBSIDENCE AND DRYING ALOFT MOVE IN. THUS BY MID AFTERNOON BEST
SHOWER THREAT WILL BE EAST OF INTERSTATE 29...BUT WOULD EXPECT THESE
TO BE EVEN LIGHTER GIVEN THE DRYER AMBIENT AIRMASS.

NOT REALLY ANY INSTABILITY OUT THERE...AS VERIFIED BY THE LACK OF
LIGHTNING IN THE CURRENT ACTIVITY. NOT MUCH CHANGES WITH THE SYSTEM
AS THE DAY PROGRESSES...SO NOT LIKING THUNDER CHANCES AND REMOVED
FROM THE FORECAST. ANY ELEVATED INSTABILITY SEEMS TO DEVELOP BEHIND
THE BEST FORCING IN A SUBSIDENT AND CAPPED REGIME. CLOUD COVER
SHOULD STICK AROUND MUCH OF THE DAY...AND THUS TRENDED HIGHS DOWN
TOWARDS THE COOLER RAW GUIDANCE VALUES. WILL BE QUITE BREEZY AS WELL
WITH A 900MB JET AROUND 40 KTS MOVING OVERHEAD. POOR MIXING WILL
LIMIT HOW MUCH OF THIS CAN REACH THE SURFACE...BUT WOULD STILL
EXPECT GUSTS AROUND 30 MPH TODAY.

ANOTHER LOBE OF ENERGY WILL SWING THROUGH TONIGHT AS THE MAIN TROUGH
AXIS PUSHES ACROSS. THUS SEEMS LIKELY SHOWER ACTIVITY WILL INCREASE
AGAIN TONIGHT WITH THAT FEATURE...SO INCREASED POPS. WITH COOLER
TEMPERATURES ALOFT...ELEVATED INSTABILITY IS GREATER TONIGHT. THUS
ACTUALLY THINK THE THUNDERSTORM THREAT WILL END UP GREATER...SO
WHILE NOTHING WILL BE SEVERE...SHOULD SEE MORE IN THE WAY OF
LIGHTNING ACTIVITY TONIGHT. BEST COVERAGE SHOULD AGAIN BE SOUTH OF
INTERSTATE 90 WHERE BETTER SUPPORT IS...BUT STILL A CHANCE FURTHER
NORTH.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 359 AM CDT TUE SEP 23 2014

THE UPPER LOW CONTINUES TO TRUDGE EAST OF THE FORECAST AREA ON
WEDNESDAY...ALLOWING THE REMAINING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS EAST OF INTERSTATE 29 TO SLOWLY TAPER OFF FROM WEST TO
EAST THROUGH AROUND MID AFTERNOON. THE LOW BECOMES WASHED OUT UNDER
THE EXPANDING LARGE SCALE UPPER RIDGE. WITH DEVELOPING SUBSIDENCE
...THE PERSISTENT LOW STRATUS WILL BEGIN CLEARING IN THE WEST ON
WEDNESDAY. WITH A LIGHT SOUTHERLY WINDS...MUCH MILDER TEMPERATURES
WILL RESULT IN SOUTH CENTRAL SD WHERE HIGHS WILL BE NEAR 80.
ELSEWHERE...THE LOW TO MID 70S ARE EXPECTED EAST OF THE JAMES RIVER.

MILD...PLEASANT AND DRY EARLY FALL WEATHER RETURNS FOR THE REMAINDER
OF THE WEEK UNDER THE UPPER LEVEL RIDGE. WITH ABUNDANT SUNDAY AND
SOUTHERLY LOW LEVEL FLOW...TEMPERATURES REBOUND TO AT OR ABOVE
NORMAL READINGS DURING THE PERIOD...MAINLY IN THE 70S. BREEZY
SOUTHERLY WINDS DEVELOP FRIDAY AND SATURDAY AHEAD OF A DEEP UPPER
LEVEL PACIFIC TROUGH WHICH WILL BEGIN APPROACHING THE REGION EARLY
NEXT WEEK. CYCLOGENESIS DEVELOPS IN THE HIGH PLAINS BEGINNING ON
MONDAY AND WILL BRING THE NEXT CHANCE OF SHOWERS AND THUNDERSTORMS
INTO OUR WESTERN FORECAST AREA ON MONDAY. MODELS SHOWING SOME DECENT
AGREEMENT WITH THE TIMING OF THIS FEATURE...SO WILL LEAVE LOW CHANCE
MENTION ON MONDAY IMPROVING TO CHANCES AT NIGHT AREA-WIDE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1208 PM CDT TUE SEP 23 2014

SCATTERED SHOWERS WILL CONTINUE THROUGH MID AFTERNOON IN AREAS
FROM THE JAMES RIVER VALLEY AND EASTWARD...BEFORE DIMINISHING IN
THE LATER AFTERNOON. WILL HAVE LINGERING STRATUS THROUGH THE JAMES
RIVER VALLEY INTO WEDNESDAY MORNING. SHOWERS AND ISOLATED
THUNDERSTORMS MAY REDEVELOP LATER TONIGHT ACROSS PORTIONS OF THE
AREA...AFFECTING MAINLY KSUX AFTER 09Z.

&&

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

$$

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



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