Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 261940
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
240 PM CDT TUE AUG 26 2014

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 237 PM CDT TUE AUG 26 2014

ONCE AGAIN THE FOCUS IN THE SHORT TERM WILL BE THE CONVECTION CHANCES
ACROSS THE AREA.  LOOKS LIKE THE EVENING WILL BE FAIRLY QUIET ACROSS
THE AREA AS THE FRONTAL BOUNDARY STAYS WELL TO THE SOUTH OF THE
AREA....CLOSER TO THE I-80 CORRIDOR.  AND WITH THE CONTINUATION OF
THE NORTHEASTERLY SURFACE FRONT...I WOULD NOT EXPECT THE FRONT TO
MOVE MUCH TO THE NORTH.  WITH THAT IN MIND...I HAVE POPS FAIRLY LOW
ACROSS MOST OF THE AREA THROUGH 09Z.  AFTER 09Z...START TO INCREASE
THE POPS AS ALL HIRES MODELS POINT TO THE CONVECTION DEVELOPING
RAPIDLY AS THE FRONT MOVES NORTH.  WENT WITH LIKELY POPS ACROSS THE
SOUTHERN TIER OF COUNTIES BY 12Z BUT DIDNT GET CARRIED AWAY WITH IT
AS I THINK THE MODELS MAY BE A LITTLE TOO FAR NORTH WITH FRONT AND
THEREFORE WITH CONVECTION.

WEDNESDAY LOOKS TO BE FAIRLY CLOUDY ACROSS THE AREA AND FAIRLY
WET...ESPECIALLY ACROSS THE SOUTH.  ALL MODELS INDICATE A STRONGER
WAVE TO BE EJECTED TOWARDS THE TRI STATE AREA DURING THE LATER
AFTERNOON AND EVENING AND THEREFORE INCREASED POPS TOWARDS THE
NORTHEAST PORTION OF THE CWA.  AREAS THAT DONT SEE THE PRECIP WONT
ESCAPE THE INFLUENCE OF THE WAVE AS THE CLOUDS WILL BE WIDESPREAD.
AND TEMPS WILL BE RELATIVELY COOL ONCE AGAIN FOR WEDNESDAY.  LOWERED
HIGHS A TAD FROM EARLIER FORECAST...BUT MAY NOT HAVE LOWERED THEM
ENOUGH.  THIS WILL ESPECIALLY BE TRUE IF THUNDERSTORMS PRODUCE LOW
LEVEL COLD POOL IN WHICH CASE WE COULD BE STUCK IN THE 60S IN SOME
OF THE AREA.


.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 237 PM CDT TUE AUG 26 2014

HEAVY RAIN SEEMS TO BE A GOOD BET ACROSS THE CWA WEDNESDAY NIGHT
INTO THURSDAY MORNING...AS A MUCH MORE DYNAMIC SHORTWAVE MOVES NORTHEAST
INTO THE REGION. RAINFALL COVERAGE AND RATES WILL GREATLY INCREASE
WEDNESDAY NIGHT AS LOW LEVEL JET INCREASES. AMPLIFYING PRECIPITATION
IS THE FACT THAT THE CWA WILL BE TEMPORARILY CAUGHT IN THE FAVORABLE
ZONES OF A DOUBLE JET STRUCTURE. WITH PWAT VALUES SO HIGH...OVER 2
INCHES...COULD SEE RAINFALL TOTALS APPROACH A FEW INCHES. LATER
SHIFTS WILL NEED TO CONSIDER A HYDROLOGIC WATCH OF SOME TYPE. FOR
NOW...WILL INCLUDE HEAVY RAIN IN GRIDS AND BUMP UP POPS FURTHER.

THURSDAY REMAINS A TRICKY FORECAST AS LARGER SYNOPTIC TROUGH REMAINS
SITUATED ACROSS COLORADO. DEPENDING ON THE TIMING OF THE INITIAL
SHORTWAVE MOVING THROUGH THE AREA...LOW-LVL CONVERGENCE ZONE REMAINS
SPRAWLED ACROSS THE REGION AND WOULD FAVOR REDEVELOPMENT DURING THE
DAY...ESPECIALLY OVER THE SOUTHEASTERN TWO THIRDS OF THE CWA.
TEMPERATURES WILL BE HIGHLY DEPENDENT ON CLOUD COVER.

MODELS IN GOOD AGREEMENT NOW...PULLING THE SYNOPTIC TROUGH THROUGH
THE MID-MISSOURI RIVER VALLEY ON FRIDAY AND SATURDAY.  THIS WOULD
KEEP A CHANCE OF RAIN ACROSS THE SOUTHEASTERN CWA INTO FRIDAY
NIGHT...AND KEEP THE POTENTIAL FOR ADDITIONAL HEAVY RAIN OVER
NORTHWESTERN IOWA AND SOUTH CENTRAL MINNESOTA.

A TEMPORARY PERIOD OF DRY WEATHER ANTICIPATED FOR THE WEEKEND AS
TROUGHING DIGS BACK INTO THE PACIFIC NORTHWEST. TEMPERATURES WILL
RUN NEAR OR SLIGHTLY ABOVE SEASONAL NORMALS. THE NEXT CHANCE OF RAIN
WILL ARRIVE SUNDAY NIGHT AND MONDAY AS A COLD FRONT PUSHES THROUGH
THE AREA.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1215 PM CDT TUE AUG 26 2014

NOT MUCH GOING TO AFFECT AVIATION THROUGH THE FIRST 12 HOURS. CIGS
MAY OCCASIONALLY BECOME MVFR BUT MAY PUSH OF LOWER CIGS AND
INCREASING PRECIP WILL HOLD OFF UNTIL WELL AFTER 06Z AND MAIN TAF
LOCATION TO BE AFFECTED WILL BE KSUX. FEEL MAIN PRECIP WILL SET UP
TO THE SOUTH OF KSUX BUT BEGINTO PUSH NORTHWARD WITH TIME.
THEREFORE INLCUDED A TEMPO GROUP AROUND 12Z FOR KSUX. PRECIP
CHANCES WILL DROP OFF DRAMATICALLY AS YOU GO NORTH.


&&

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

$$

SHORT TERM...HEITKAMP
LONG TERM...DUX
AVIATION...HEITKAMP






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