Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 251733
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1233 PM CDT TUE AUG 25 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 342 AM CDT TUE AUG 25 2015

GRADUAL INCREASE IN RIDGING ALOFT OVER THE NEXT 24 HOURS WILL DO
LITTLE TO CAUSE A DEVIATION FROM THE QUIET AND EXTREMELY PLEASANT
CONDITIONS ACROSS THE AREA. ADDED BONUS TODAY WILL BE LIGHT WINDS
NEAR THE RIDGE AXIS...WITH MIXING FAVORING MAINLY 70S ACROSS THE
AREA. A BIT OF CIRRUS SHOULD NOT INTERRUPT A MAINLY SUNNY DAY. STILL
A BIT RIDGY AT LOWER LEVELS ACROSS THE EAST TONIGHT...AND THIS
SHOULD AGAIN ALLOW SOME CHILLIER TEMPS IN THE MID TO UPPER 40S EAST
OF I 29.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 342 AM CDT TUE AUG 25 2015

SOUTHEAST WINDS WILL BE ON THE INCREASE ON WEDNESDAY AS THE UPPER
LEVEL RIDGING OVER THE HIGH PLAINS EXPANDS EASTWARD AND SURFACE HIGH
PRESSURE MOVES INTO THE MISSISSIPPI VALLEY. MOISTURE WILL BEGIN TO
RETURN IN EARNEST WITH DEWPOINTS IN THE 60S SPREADING ACROSS THE
FORECAST AREA. SKIES WILL BE MOSTLY SUNNY TO PARTLY CLOUDY WITH DRY
CONDITIONS PREVAILING. HIGHS WILL BE IN THE UPPER 70S EAST AND THE
80S WEST...EVEN APPROACHING 90 IN SOUTH CENTRAL SD.

BY WEDNESDAY EVENING...SURFACE LOW PRESSURE DEEPENS TO OUR WEST
WHILE A POTENT UPPER FLATTENS THE RIDGE AS IT DIGS OVER THE NORTHERN
ROCKIES. MID LEVEL MOISTURE IS EXPECTED TO INCREASE ACROSS THE
WESTERN FORECAST AREA WHERE THE MID LEVEL THERMAL BOUNDARY NOSES
EAST. EXPECT SOME SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP
AFTER MIDNIGHT MAINLY ALONG AND WEST OF THE JAMES RIVER. SCATTERED
STORMS WILL SPREAD EASTWARD IN THE MORNING...HOWEVER BY AFTERNOON
THE UPPER WAVE ARRIVES IN THE WESTERN FORECAST AREA WHILE THE
SURFACE LOW DEEPENS NEARBY. STILL SEEING SOME PRETTY SIGNIFICANT
DIFFERENCES IN THE LOCATION OF THE UPPER LOW AND SURFACE BOUNDARIES
WHICH SPELL SOME MAJOR DIFFERENCES IN PRECIPITATION FOCUS. THE
AMERICAN MODELS...GFS AND NAM ARE FURTHER NORTH WITH THE LOW
CENTER...TAKING THE UPPER LOW AND WARM FRONT THROUGH THE FORECAST
AREA. THE CANADIAN AND EUROPEAN HOWEVER BRING THE LOW CLOSER TO THE
I80 CORRIDOR WHICH WOULD RESULT IN A MUCH DRIER FORECAST FOR THE
NORTHERN HALF OF THE FORECAST AREA. TRIED TO SPLIT THE DIFFERENCE
WITH THE FORECAST...WITH THE HIGHEST CHANCES AND QPF SOUTH OF I90 ON
THURSDAY AFTERNOON AND THURSDAY NIGHT.

UPPER LOW SLOWLY EXITS THE AREA TO THE WEST ON FRIDAY. SHOWERS AND
STORMS TAPER OFF FROM WEST TO EAST. WITH CLEARING SKIES IN THE
WEST...HIGHS WILL BE WARMEST IN THE LOWER 80S...HOWEVER CLOUDS AND
SHOWERS WILL KEEP TEMPERATURES LOCKED RIGHT AROUND 70 IN THE FAR
EAST.

RIDGING MAKES A QUICK REBOUND BEHIND THE EXITING WAVE FRIDAY NIGHT
AND SATURDAY...AND BECOMES LOCKED OVER THE CENTRAL PLAINS INTO THE
START OF NEXT WEEK. THIS WILL SPELL A WARMING TREND WITH HIGHS
RETURNING TO THE 80S AND NEAR 90 FOR THE WEEKEND. THE GFS TRIES TO
BRING A WAVE OVER TOP OF THE RIDGE SUNDAY NIGHT...HOWEVER THE GEM
AND ECMWF HOLD TIGHT TO THE RIDGE. WILL LEAVE SOME SLIGHT CHANCE
POPS DURING THIS PERIOD DUE TO UNCERTAINTY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1230 PM CDT TUE AUG 25 2015

VFR CONDITIONS WITH LIGHT WINDS THROUGH 12Z/26TH AS SURFACE RIDGE
REMAINS OVER THE AREA. COULD SEE A BAND OF ELEVATED SMOKE ACROSS
THE REGION THIS AFTERNOON INTO TONIGHT. SOUTHEASTERLY WINDS WILL
INCREASE AS THE RIDGE SCOOTS EAST ON THE 26TH.

&&

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

$$

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


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