FXUS63 KFSD 050911
AFDFSD

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
310 AM CST SUN FEB 5 2012

.DISCUSSION...
FOG AND STRATUS ENCOMPASSING ALL BUT GREGORY COUNTY AT 9Z THIS
MORNING...AND THIS WILL BE THE MAIN PROBLEM THROUGH THE DAY. LATEST
SATELLITE LOOP SUGGESTS THAT THE STRATUS ALONG AND WEST OF THE JAMES
IS PRETTY SHALLOW AND EVEN THAT CLOSER TO THE I29 CORRIDOR DOES NOT
LOOK TOO DEEP. THE AREA EAST OF INTERSTATE 29 LOOKS LIKE IT HAS THE
POTENTIAL TO REMAIN A LITTLE MORE PERSISTENT THROUGH THE DAY...SO
HAVE EXTENDED THE CLOUDINESS INTO EARLY AFTERNOON EAST OF THE JAMES
RIVER VALLEY WITH RAPID AFTERNOON CLEARING. YESTERDAYS VISIBLE LOOP
ALSO HINTED THAT SOME POTENTIALLY FRESH SNOW COVER WAS ACROSS FAR
WESTERN CHARLES MIX INTO GREGORY COUNTY SO DROPPED TEMPERATURES
ABOUT 5 DEGREES COOLER THAN POTENTIAL SUGGESTS. OTHERWISE...WENT
WITH A PRETTY SLOW DIURNAL RISE THIS MORNING...THEN RAPID WARMING IN
THE AFTERNOON AS WEST WINDS...A MILD AIR MASS AND DECREASED CLOUDS
ALLOWS FOR A NICE AFTERNOON. SHOOTING FOR HIGHS MAINLY IN THE
40S...CLOSE TO 50 FROM THE JAMES VALLEY WEST.

WESTERLY FLOW REMAIN IN PLACE THROUGH THE NIGHT WHICH SHOULD MAKE
FOR A MILD NIGHT. KEPT LOWS MAINLY IN THE MID 20S...WITH LOWER 30S
ALONG THE BUFFALO RIDGE. DECENT SET UP FOR SOME ENHANCED FLOW AND
NEAR PERPENDICULAR FLOW TO THE RIDGE. THIS SHOULD AID IN MML
TEMPERATURES STAYING NEAR AND ABOVE THE FREEZING MARK MUCH OF THE
NIGHT.

BOUNDARY CONTINUES TO LOOK JUST A BIT FASTER FOR MONDAY...BUT STILL
VERY MILD AHEAD OF THE BOUNDARY...ESPECIALLY IN NEAR THE MISSOURI
RIVER INTO NORTHWEST IOWA. SINCE PRETTY MUCH NO NEW SNOW COVER FULL
MIXING POTENTIAL SHOULD YIELD NEAR 50 IN SPOTS. DO HAVE TEMPERATURES
DROPPING PRETTY QUICKLY NORTH OF INTERSTATE 90 LATE IN THE AFTERNOON
AND FAIRLY FAST THE REMAINDER OF THE CWA DURING THE EVENING AS THE
COLD FRONT BARRELS THROUGH. NOT REALLY EXPECTING ANY PRECIPITATION
WITH THIS FRONT...JUST COLD AND BREEZY.

DID DECREASE LOWS JUST A BIT MONDAY NIGHT AND HIGHS A BIT TUESDAY
BASED ON MIXING POTENTIAL AND COLDER AIR MASS. SHOULD BE FAIRLY
CLOUD MOST OF THE NIGHT AND MORNING...BUT CLEARING FROM THE NORTH ON
TUESDAY AFTERNOON. LOWS MAINLY IN THE TEENS AND HIGHS IN THE 20S.

TUESDAY NIGHT WILL SEE HIGH PRESSURE SLIP THROUGH BUT WEAK RETURN
FLOW MAY SET UP JUST SOON ENOUGH OVERNIGHT TO KEEP FROM HAVING TOO
MUCH OF A RADIATIONAL DROP OFF...ESPECIALLY SINCE THERE IS VIRTUALLY
NO NEW SNOW COVER. WEDNESDAY SHOULD ALSO SEE TEMPERATURES REBOUND
BACK TO ABOVE NORMAL.

IN THE LATTER PERIODS(THU/SAT)...THE MODELS ARE IN SOMEWHAT BETTER
AGREEMENT IN THE TIMING OF THE NEXT SHOT OF COLDER AIR...WHICH
SWINGS THROUGH ON THURSDAY AND REMAINS ENTRENCHED THROUGH FRIDAY.
MODEL DISAGREEMENT CROPS BACK UP ON SATURDAY AS THE ECMWF SETS UP A
WARMER RETURN FLOW WHILE THE GFS AND GFS ENSEMBLE KEEP THE COLDER
AIR LOCKED IN. REGARDLESS...SEE VERY LITTLE CHANCE FOR ANY SNOWFALL
THIS GO AROUND BUT WILL NEED TO WATCH THURSDAY FOR SOME LIGHT SNOW
AS IT SEEMS LIKE WE ALMOST ALWAYS MANAGE TO SQUEEZE OUT A FEW TENTHS
DURING ARCTIC FRONTAL PASSAGES.

&&

.AVIATION.../FOR THE 06Z TAF ISSUANCE/
AREA OF IFR STRATUS CONTINUES TO DROP SOUTHWARD ACROSS THE AREA ON A
NORTHERLY/NORTHWESTERLY LOW LEVEL FLOW. ANTICIPATE THAT IT WILL NOW
MAKE IT ALL THE WAY INTO THE SOUTHERN PORTIONS OF THE FORECAST
AREA...THOUGH SOME UNCERTAINTY ON ARRIVAL AT KSUX...GENERALLY IN THE
08Z TO 09Z TIME FRAME. VISIBILITIES ARE ALSO BEGINNING TO DROP
THROUGH THE NORTHERN I 29 CORRIDOR INTO SOUTHWESTERN MINNESOTA...AND
ANTICIPATE LOCALIZED IFR VISBYS ACROSS THE AREA. IMPROVING
CONDITIONS EXPECTED AFTER 16Z ON SUNDAY.

&&

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

&&

$$




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