Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 240341
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1041 PM CDT THU OCT 23 2014

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 405 PM CDT THU OCT 23 2014

EARLIER FOG/STRATUS GONE BY NOON ACROSS NORTHWEST IOWA AND SOUTHWEST
MINNESOTA...AND WIDESPREAD SUNSHINE HAS BEEN THE RULE OVER THE AREA
THROUGH THE AFTERNOON. HOWEVER...BAND OF CIRRUS WORKING EASTWARD
ACROSS THE RUSHMORE STATE...AND REMAINS TO BE SEEN IF THAT WILL BE
THICK ENOUGH IN SPOTS TO IMPAIR VIEWING OF THE PARTIAL SOLAR ECLIPSE
LATE AFTERNOON ACROSS SOUTHEAST SOUTH DAKOTA. VERY DRY AIR HAS MIXED
DOWN FOR HIGHER ELEVATIONS...BUT AREAS TO THE SOUTH TOWARD SOUTH
CENTRAL NEBRASKA YET HAVE A BIT OF STRATUS TO REMOVE...AND
TRAJECTORY OF HIGHER LOW LEVEL DEWPOINTS TO DEAL WITH. INVERSION
TONIGHT WILL BE IN PLACE AS TEMPS CONTINUE TO WARM ALOFT...AND
SHOULD PROVIDE AN EFFECTIVE CONDUIT TO TRANSPORT THIS
MOISTURE NORTHWARD. LIKELY WILL SEE DEVELOPMENT OF LOW CLOUDS AND
FOG AGAIN TONIGHT. NAM AND RAP ARE QUITE INDICATIVE OF THE
POTENTIAL...WITH SREF PROBABILITIES GARNERING ATTENTION IN THE 09Z-
12Z WINDOW.  HOWEVER...A BIT MORE WIND...DAY OF DRYING...AND SOME
HIGHER LEVEL CLOUDINESS GIVES THIS A BIT MORE STRATUS OVER FOG LOOK
FOR THE LATTER OVERNIGHT AND EARLY MORNING. TRAJECTORY OF FLOW WOULD
FAVOR MAINLY EAST/SOUTHEAST HALF TO TWO THIRDS OF CWA.  WIND SHIFT
MOVES INTO THE JAMES VALLEY EARLY MORNING...AND THIS INCREASE IN
WESTERLY COMPONENT WILL PROGRESS EASTWARD ENOUGH TO HELP ERODE LOWER
CLOUDS FAIRLY EFFECTIVELY...IF THE WEST/SOUTHWEST FLOW OFF SURFACE
IS NOT ENOUGH TO SPEED ALONG ON ITS OWN.

AFTER REMOVAL OF THE LOWER CLOUDS/FOG...FRIDAY WILL SHAPE UP TO BE A
VERY NICE FALL DAY. WINDS PICKING UP A WESTERLY COMPONENT WILL FAVOR
MIXING...AND HAVE ASSUMED THAT THE LACK OF GREATER MIXING DEPTH IN
THE MODELS IS IN ERROR.

WILL HAVE AN INCREASE IN HIGHER LEVEL CLOUDS AS STRONG WAVE MOVES
NORTH OF THE AREA DURING THE DAY...BUT SHOULD STILL MAINTAIN A
MOSTLY SUNNY TO PARTLY CLOUDY BALANCE TO THE DAY. THIS COULD IMPACT
WARMING BY A COUPLE DEGREES...BUT OVERALL WILL SEE 70S ACROSS THE
AREA...AND WILL SEE IF ENOUGH MIXING IN PLAY TO BRING SOME READINGS
AROUND 80 WEST OF THE JAMES RIVER VALLEY.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 405 PM CDT THU OCT 23 2014

PLEASANT WEATHER CONTINUES INTO THE WEEKEND WITH DRY
CONDITIONS AND MOSTLY SUNNY SKIES. SLIGHTLY COOLER TEMPERATURES
FILTER INTO THE REGION WILL COOLER UPPER LEVEL FLOW IN PLACE. WHILE
WINDS ON SATURDAY WILL GENERALLY BE AROUND 10 MPH OR LESS...WINDS
TURN SOUTHEASTERLY AND BECOME BREEZY ON SUNDAY AFTERNOON. HIGHS BOTH
DAYS WILL BE IN THE MID 60S TO NEAR 70.

BROAD UPPER LEVEL TROUGH DIGS INTO THE NORTHERN ROCKIES SUNDAY NIGHT
AND NOSES INTO THE NORTHERN AND CENTRAL HIGH PLAINS ON MONDAY.
INITIAL SHORT WAVE MOVING THROUGH THE AREA SUNDAY NIGHT SHOULD
MAINLY RESULT IN SOME INCREASED CLOUDS...BUT OTHERWISE REMAIN DRY
FOR THE FORECAST AREA WITH VERY DRY LOW LEVELS. MAIN WAVE ARRIVES
MONDAY NIGHT. MODEL TIMING IN DECENT AGREEMENT FOR THE ONSET...BUT
THE LOCATION AND STRENGTH OF THIS SYSTEM IS LESS CERTAIN. THE GFS
IN PARTICULAR DEVELOPS A MUCH STRONGER NEGATIVELY TILTED WAVE THAT
BECOMES CUT OFF AND LIFTS INTO THE UPPER GREAT LAKES. WITH A
SLOWER AND STRONGER SOLUTION...THE GFS HOLDS ONTO PRECIPITATION IN
OUR FORECAST AREA LONGEST. THE BEST CHANCES FOR RAIN LOOK TO BE
MONDAY AND MONDAY NIGHT...BUT LEFT SOME ISOLATED MENTION MAINLY
ACROSS OUR EASTERN TWO THIRDS ON TUESDAY WITH THE UNCERTAINTY OF
THE TIMING. WITH CLOUDS..RAIN SHOWERS AND COOLER AIR ALOFT
ARRIVING...TEMPERATURES WILL BE COOLER AS WELL. HIGHS ARE EXPECTED
IN 50S ON TUESDAY WITH A VERY BRISK NORTHWEST WIND.

TUESDAY NIGHT THROUGH THURSDAY WILL BE DRY WITH NORTHWEST FLOW
KEEPING TEMPERATURES NEAR SEASONAL NORMALS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1031 PM CDT THU OCT 23 2014

UNCERTAINTY REMAIN IN REGARDS TO THE DEVELOPMENT OF STRATUS/FOG
LATE TONIGHT AND INTO DAYBREAK. CIRRUS REMAINS RATHER THICK ACROSS
THE AREA...HOLDING TEMPERATURES UP. HOWEVER...AS BREAKS
DEVELOP...TEMPERATURES WILL FALL TOWARDS THE ELEVATED CROSSOVER
TEMPERATURE IN THE 46-47 DEGREE RANGE. A WEAK SFC LOW OVER
CENTRAL SD MAY ALSO ADVECT SHALLOW BOUNDARY LAYER MOISTURE
NORTHWARD INTO THE REGION...AND PRIOR TO A WEAK FRONT MOVING
THROUGH AROUND DAYBREAK...POTENTIAL CONTINUES FOR FOG/STRATUS
DEVELOPMENT. GIVEN LOWER CONFIDENCE ON COVERAGE OF LIFR OR LOWER
CONDITIONS...WILL ONLY USE A TEMPO GROUP FOR FSD.

THE GOOD NEWS IS THAT DRIER AIR SHOULD FILTER QUICKLY INTO THE
AREA AFTER DAYBREAK AND SHOULD ALLOW SKIES TO SCOUR RATHER
QUICKLY. VFR CONDITIONS AND LIGHT WESTERLY WINDS LIKELY THROUGH
FRIDAY.

&&

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

$$

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



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