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000
FXUS63 KFSD 041135
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
535 AM CST TUE MAR 4 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 232 AM CST TUE MAR 4 2014

MAIN CONCERN TODAY CONTINUES TO BE SHORT WAVE ENERGY AND THE CHANCES
FOR SNOW. THE WAVE IS RATHER HARD TO FOLLOW ON THE VARIOUS MODELS
USING UPPER QG FORCING...EVEN AT THE 80KM AND 90KM SCALES. HOWEVER
IN GENERAL MOST OF THE DYNAMICS IS TAKING A TRACK THROUGH OUR
NORTHERN ZONES...BACKED UP BY THE LATEST NAM PV FIELDS. THE WAVE IS
A BIT WEAK...WITH JET ENERGY NOT OVERLY STRONG EITHER. HOWEVER THE
OVERALL PROFILE SHOWS A DECENT DEPTH OF SATURATION IN ABOUT A 6 HOUR
WINDOW FOR ANY PARTICULAR LOCATION...GENERALLY ALONG AND NORTH OF A
HURON TO MITCHELL...TO SIOUX FALLS AND STORM LAKE IA LINE TODAY AND
THIS EVENING. SOUTH OF THAT LINE...THE MOISTURE DEPTH WANES RATHER
RAPIDLY WHICH WILL HINDER SNOWFALL AMOUNTS IN OUR SOUTHERN ZONES.
HOWEVER BELIEVE THAT THE NAM AND GFS ARE A BIT STRONG IN THEIR
RESPECTIVE QPF OUTPUTS...AS THEY WERE WITH THE WEAK WAVE LAST
FRIDAY...ESPECIALLY THE NAM. THEREFORE PREFERRED THE ECMWF AND GEM
FOR GUIDANCE ON AMOUNTS...AND USED THE HPC MEAN SNOW RATIO WHICH
LOOKED VERY REASONABLE AT ABOUT 14 OR 15:1. THE DENDRITIC LAYER
DEPTH IS NOT VERY DEEP AND CONFINED TO THE MID LEVELS...SO HIGH
SNOW/LIQUID RATIOS SHOULD BE ABSENT IN THIS EVENT. STORM TOTALS
STILL LOOK LIKE CLOSE TO TWO INCHES IN SOUTHWEST MN...WITH THE ONE
INCH SNOW LINE CLOSE TO A LINE RUNNING FROM HURON...TO SIOUX FALLS
AND SPENCER IA. THE MO RIVER VALLEY LOOKS TO GET A DUSTING. WINDS
WILL NOT BE STRONG WITH THIS EVENT...AND HIGHS LOOKED ON TARGET FROM
THE PREVIOUS FORECAST.

TONIGHT...THE WAVE MOVES EASTWARD WITH LINGERING EVENING SNOWFALL
VERY LIKELY FROM BROOKINGS TO SIOUX FALLS...SOUTHWEST MN AND EXTREME
NORTHWEST IA. WITH WINDS LIGHT...IT ALSO STILL APPEARS THAT LOW
CLOUDS WILL BE FOUND THROUGHOUT MUCH OF OUR FORECAST AREA WHICH
SHOULD HELP TO KEEP LOWS FROM TANKING. WITH THE ANTICIPATED CLOUD
COVER...USED THE MILDER BIAS CORRECTED VALUES FOR LOWS.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 232 AM CST TUE MAR 4 2014

LOW CLOUD COVER EXPECTED TO BE FAIRLY SOLID AT THE CRACK OF DAYBREAK
WEDNESDAY LOOKS PRETTY STUBBORN GIVEN THE FAIRLY HEALTHY DEPTH OF
MOISTURE AND PROJECTED SOUNDINGS KEEPING THE LOWER LEVELS COOL. WILL
GO    FOR VERY SLOWLY BREAKING IT UP WEST OF THE JAMES RIVER DURING
THE DAY AND KEEPING IT TO THE EAST. HAVE GONE FOR A LITTLE MORE SLOW
BREAKING UP WEDNESDAY NIGHT AND THURSDAY AS THE LOWER LEVEL FLOW
TURNS SOUTH SOUTHWESTERLY AND STRENGTHENS. THIS FLOW ACTUALLY STAYS
PRETTY MOIST AT LOW LEVELS ON MODEL OUTPUT. MODELS CAN BE TOO SLOW
ON DRYING OUT THE LOW LEVELS ONCE THE FLOW CHANGES LIKE THIS...AND
CAN SEE A STRONGER CLEARING BY THURSDAY. HOWEVER...THE MILD LOW
LEVEL AIR FLOWING OVER LINGERING SNOW COVER COULD SLOW THIS DOWN.
FEEL PRETTY CONFIDENT ABOUT THE CLOUDS HANGING AROUND LONGER
WEDNESDAY INTO WEDNESDAY EVENING ESPECIALLY EAST...BUT CONFIDENCE
DROPS BY THURSDAY WITH A MOSTLY CLOUDY OR MOSTLY SUNNY DAY SEEMINGLY
REALISTIC. RIGHT NOW EXPECT NO PRECIPITATION WEDNESDAY THROUGH
THURSDAY...AND THAT INCLUDES DRIZZLE/FREEZING DRIZZLE WITH THE LOW
CLOUDS...THOUGH AN EVEN STRONGER TILT IN FAVOR OF THE STUBBORN LOW
LEVEL MOISTURE COULD CHANGE THAT.

SURFACE TEMPERATURES DURING THIS WARMUP TIME WILL OF COURSE NOT
REFLECT THE STRENGTH OF THE WARMING ALOFT...THOUGH THIS FACTOR FOR
THURSDAY IS ALMOST AS UNCERTAIN AS THE CLOUD COVER. IT WOULD BE
EASIER TO KEEP THE LOW LEVEL MOISTURE LOCKED IN FOREVER DURING THE
MIDDLE OF WINTER...WHICH DESPITE THE LAST COUPLE DAYS IS PAST US...
GIVING WAY TO BETTER HEATING AS WE APPROACH THE EQUINOX. FOR NOW WE
LOOK FOR EVERYONE TO STAY AT OR BELOW FREEZING WEDNESDAY...AND TO
WARM TO OR ABOVE FREEZING THURSDAY...WITH UPPER 40S THURSDAY OVER
THE SOUTHWEST CORNER SOUTH OF CHAMBERLAIN/9V9.

A COLD FRONT COMING THROUGH THURSDAY NIGHT AND EARLY FRIDAY MORNING
WILL REVERSE THE WARMING FOR A DAY OR TWO...THOUGH IN LIGHT OF THE
RECENT COLD AND THE STUBBORNNESS OF THE FIRST WARMUP...FRIDAY INTO
SATURDAY MAY STILL SEEM MILD THOUGH BELOW NORMAL. AS FOR AS
PRECIPITATION...THERE SEEMS ENOUGH MEAGER SUPPORT TO KEEP A SLIGHT
MENTION OF LIGHT SNOW WITH/BEHIND THE FRONT MAINLY NORTHEAST...BUT
DO NOT SEE ANYBODY GETTING CLOSE TO AN INCH.

LATE SATURDAY THROUGH SUNDAY STILL SEEMS LIKE A MORE SERIOUS WARMUP
ESPECIALLY SINCE IT CURRENTLY SEEMS LIKE THE AIR WILL BE NOTABLE
DRIER THAN WITH THE FIRST WARMING ATTEMPT WEDNESDAY. EVEN THE MORE
CONSERVATIVE GFS IS COMING AROUND CLOSER TO THE VERY STRONG WARMING
OF THE EC. THERE IS SOME DOUBT OF COURSE ON HOW WARM IT WILL GET
WITH LINGERING SNOW COVER...BUT THAT CAN GO SURPRISINGLY FAST IN
MARCH. AM CURRENTLY GOING UPPER 30S NORTHEAST TO MID 50S SOUTHWEST
FOR SUNDAY BUT WE WILL SEE. MONDAY COULD BRING SLIGHT COOLING ALOFT
BUT SURFACE WARMING...PARTLY DUE TO GETTING RID OF A LOT OF SNOW
COVER ON SUNDAY. WITH THE RIDGING DURING THIS TIME AND THE RELATIVE
DRYNESS OF THE FLOW AT THE SURFACE AND ALOFT...DO NOT EXPECT ANY
PRECIPITATION THROUGH MONDAY DAYTIME. SOME COOLING IS EXPECTED NEXT
WEEK AFTER THE FORECAST PERIOD...BUT WE ARE SEEMINGLY DONE WITH ANY
FRIGID ARCTIC AIR.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 534 AM CST TUE MAR 4 2014

AS AN UPPER AIR DISTURBANCE MOVES ACROSS THIS AREA TODAY AND TONIGHT...
VFR CONDITIONS THIS MORNING WILL GIVE WAY TO IFR AND MVFR IN SNOW...
ESPECIALLY FOR AREAS ALONG AND NORTH OF THE I 90 CORRIDOR THIS
AFTERNOON AND EVENING. FURTHER SOUTH...THE OVERALL MOISTURE PROFILE
IS NOT QUITE AS SATURATED...THEREFORE SNOW CHANCES AT KSUX ARE MORE
PROBLEMATIC WHETHER THEY WILL OCCUR OR NOT LATER TODAY. THAT
SAID...SIGNS ARE POINTING TO MVFR CEILINGS LATE TODAY AND TONIGHT
EVEN AT KSUX. MVFR CEILINGS COULD LIKELY LINGER ACROSS THIS AREA
ALL NIGHT EVEN AFTER THE SNOW ENDS...AS LIGHT WINDS FAIL TO USHER
OUT THE LOWERED CLOUD DECK.

&&

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

$$

SHORT TERM...MJ
LONG TERM...
AVIATION...MJ