Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 300341
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1041 PM CDT SAT AUG 29 2015

.UPDATE...
ISSUED AT 854 PM CDT SAT AUG 29 2015

INCREASED THE SKY COVER TONIGHT WHERE WE HAVE THE FOG ALREADY
MENTIONED. IN FACT THE CURRENT STRATUS IS BEING ADVECTED BACK INTO
OUR FORECAST AREA ALREADY AROUND THE STORM LAKE AND CHEROKEE IOWA
AREAS...USHERED IN BY THE SOUTH TO SOUTHEAST WINDS OFF THE
SURFACE. THEREFORE BY LATE TONIGHT AND EARLY SUNDAY...WOULD NOT BE
SURPRISED TO SEE A MESS OF FOG AND STRATUS FOR MANY AREAS ALONG
AND EAST OF THE I 29 CORRIDOR. THIS IS ALSO STRONGLY SUGGESTED BY
THE LATEST SREF LOW CLOUD PROBABILITIES...AS WELL AS THE RAP AND
HRRR.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 405 PM CDT SAT AUG 29 2015

SHOULD BE A QUIET NIGHT ACROSS THE AREA AS A SURFACE RIDGE OF HIGH
PRESSURE GRADUALLY SHIFTS SOUTHEAST. THIS WILL BRING AN INCREASING
SOUTHERLY FLOW TO THE AREA...BUT STILL REMAINING FAIRLY LIGHT
OVERNIGHT...ESPECIALLY IN NORTHWEST IOWA. WITH THE WET
GROUND...LIGHT WINDS AND MAINLY CLEAR SKIES SUSPECT THAT FOG AND
THIN LOW STRATUS WILL AGAIN DEVELOP ACROSS NORTHWEST IOWA SO WILL
INCLUDE THE THREAT FOR SHORT LIVED AND SPOTTY DENSE FOG. THE BEST
CHANCE FOR THIS WILL BE FROM ABOUT 9Z THROUGH 15Z AND SHOULD QUICKLY
ERODE MID TO LATE MORNING SIMILAR TO THIS MORNING. LOWS SHOULD
MAINLY BE FROM THE UPPER 50S TO LOWER 60S...WITH A FEW MID 60S IN
CENTRAL SD.

SOUTHERLY FLOW WILL INCREASE SUNDAY...BECOMING FAIRLY WINDY IN
CENTRAL SD DURING THE AFTERNOON. HIGHS WILL RANGE FROM THE LOWER 90S
IN CENTRAL SD TO NEAR 80 AROUND STORM LAKE.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 405 PM CDT SAT AUG 29 2015

FORECAST APPEARS TO BE OVERALL FAIRLY WARM AND DRY THROUGH THE
EXTENDED AS ELONGATED UPPER LEVEL RIDGE EXTENDS FROM THE DESERT
SOUTHWEST INTO THE NORTHERN PLAINS.

ON SUNDAY NIGHT INTO MONDAY MORNING...COULD SEE SOME SHALLOW FOG
DEVELOP IN THE VALLEYS OVERNIGHT...BUT SHOULD BURN OFF FAIRLY
QUICKLY LEADING TO MOSTLY SUNNY CONDITIONS.

THERE IS A WEAK BOUNDARY THAT APPROACHES THE FORECAST AREA MONDAY
AFTERNOON INTO MONDAY NIGHT...BUT FAIRLY STRONG CAPPING INVERSION
SHOULD LIMIT SURFACE BASED CONVECTION.  ELEVATED CONVECTION REMAINS
A POSSIBILITY AS THE CAPPING INVERSION IS LESS. GFS SHOWS WEAK
SHORTWAVES TRACKING ACROSS THE AREA ON TUESDAY...BUT THE ECMWF IS
SLOWER WITH THE UPPER LEVEL WAVES.  FOR NOW...LEFT POPS FOCUSED
TUESDAY NIGHT.

HAVE INCREASED TEMPERATURES THROUGH MUCH OF THE WEEK WITH UPPER
LEVEL RIDGE IN PLACE.  HAVE THROWN OUT GFS SOLUTION...AS IT IS WAY
TO WARM ALOFT COMPARED TO OTHER SOLUTIONS.  HAVE RAISED FORECAST
HIGHS INTO THE UPPER 80S TO LOWER 90S THROUGH MUCH OF THE WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1038 PM CDT SAT AUG 29 2015

MVFR STRATUS IS BEGINNING TO STREAM NORTH TO NORTHWESTWARD ACROSS
NORTHWEST IA ALONG THE LOW LEVEL FLOW. THIS TREND WILL CONTINUE
ALL NIGHT. THEREFORE AM EXPECTING IFR TO MVFR CONDITIONS TO
PREVAIL FOR MANY AREAS GENERALLY ALONG AND EAST OF THE INTERSTATE
29 CORRIDOR. THE STRATUS COULD FIRST AFFECT KSUX SHORTLY AFTER
06Z. KFSD IS QUITE A CHALLENGE...IN THAT THEY COULD BE ON THE
EDGE OF THE NORTHWARD BUILDING STRATUS LATE TONIGHT. FOR THAT
REASON...WILL INCLUDE A TEMPO IFR GROUP FOR VISIBILITY AROUND
SUNRISE SUNDAY.

&&

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

$$

UPDATE...MJ
SHORT TERM...08
LONG TERM...
AVIATION...MJ



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