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000
FXUS63 KFSD 022140
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
340 PM CST MON DEC 2 2013

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 340 PM CST MON DEC 2 2013

MORE COMPLICATED AND UNCERTAIN FORECAST BEGINS LATE TONIGHT AS A
SFC LOW AND ASSOCIATED CDFNT APPROACH THE CWA.

PREVAILING OPINION GOES MOSTLY WITH THE ECMWF FOR THIS EARLY PART OF
THE FCST PERIOD SO WILL HEAVILY WEIGHT THIS FORECAST WITH THE EC.

WARMING ALOFT AHEAD OF THE SFC LOW THAT WILL DEEPEN AHEAD OF A
LONGWAVE TROF FROM THE PAC NW WILL ADD SOME CHANCES OF FZRA BUT NO
ACCUMULATION IS EXPECTED.  SNOW AMOUNTS WILL ALSO REMAIN FAIRLY LOW
AS THE SYSTEM MOVES QUICKLY AND COLD AIR ALOFT LAGS SOMEWHAT AFTER
FROPA.

ANY SNOW THAT FALLS WILL GENERALLY BE AROUND 1 INCH OR LESS.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 340 PM CST MON DEC 2 2013

ACCORDING TO ALL MODEL GUIDANCE EXCEPT THE EC...UPPER SUPPORT FOR
THE STEADIEST SNOW NEAR THE NORTHERN EDGE OF OUR FORECAST AREA WILL
BE PULLING OUT TUESDAY EVENING. THE NCEP MODELS PROBABLY PULL A
LITTLE TOO MUCH OUT WITH INITIAL OVERDONE WAVE...AND A FAVORABLE
PATTERN FOR AREAS OF LOWER LEVEL LIGHT SNOW SEEMS TO EXIST...SO
WILL START WITH 50 OR SO POPS IN OUR NORTHEAST TUESDAY
EVENING...WELL MATCHING TUESDAY AFTERNOON...AND SLOWLY DECREASING
DURING TUESDAY NIGHT. THE EC AND GFS AND GEM HAVE ALL BEEN
KICKING OUT TOO MUCH PRECIPITATION LATELY...LAST NIGHT WAS A GOOD
EXAMPLE...AND UNDER THE DEVELOPING COLD ADVECTION REGIME...WITHOUT
THE UPPER SUPPORT PASSES BY...IT WILL BE HARD TO GET MORE THAN A
VERY FEW HUNDREDTHS OF PRECIP. THIS IS ABOVE AND BEYOND THE MODEL
DIFFERENCES. THIS WILL LEAVE CHC TO SLIGHT CHANCE POPS FOR LIGHT
SNOW...GENERALLY HIGHER NORTH...FOR TUESDAY NIGHT AND
WEDNESDAY...WITH A LINGERING SLIGHT CHANCE OF LIGHT RAIN/SNOW IN
THE FAR SOUTHEAST OVER PART OF NORTHWEST IA EARLY TUESDAY EVENING.
THIS IS AHEAD OF AND WITH THE VERY STRONG INFLOW OF VERY COLD
AIR...THE ONE THING WHICH IS IN ZERO DOUBT. TEMPERATURES WILL FALL
AT LEAST INTO MID MORNING WEDNESDAY AND SHOW ONLY A SLIGHT RISE
DURING THE DAY...WITH WIND CHILLS DIVING BELOW ZERO AND STAYING
BELOW ZERO..EXCEPT SLIGHTLY LESS COLD FAR SOUTHEAST.

WILL KEEP FLURRIES WITH SOME LINGERING LOW LEVEL MOISTURE WEDNESDAY
NIGHT...AND KEEP JUST DRY AND COLD THURSDAY THROUGH FRIDAY.
NORTHWEST WINDS WILL HOLD UP ENOUGH AHEAD OF THE ARCTIC HIGH TO
BRING IS VERY CLOSE TO WIND CHILL ADVISORY LEVELS BOTH LATE
WEDNESDAY NIGHT AND THURSDAY MORNING. WE MAY HAVE TO LOOK AT THIS
CLOSER TOT HAT TIME SINCE WE HAVE NOT OF COURSE BEEN THIS COLD SO
FAR IN THE SEASON.

THE WEEKEND SEEMS TO OFFER A LITTLE BETTER CHANCE OF SNOW BY SUNDAY
THAN YESTERDAY...WITH OTHER MODELS JOINING THE EC ON THIS. WILL GO
FOR A MENTION SATURDAY NIGHT AND SUNDAY AS PER EXTENDED GUIDANCE.
TEMPERATURES WILL BE A LITTLE LESS COLD...BUT A TESTIMONY TO THE
COLD AIR SHOT COMING IN IS THAT IT LOOKS LIKE DURING THE
WEEKEND...WE WILL ACTUALLY WARM TO HIGHS IN THE TEENS AND LOWS IN
THE SINGLE DIGITS.

FOR DAY SEVEN...NEXT MONDAY...A DRY FORECAST SEEMS IN ORDER...WITH
NOT MUCH TEMPERATURE CHANGE FROM SUNDAY...THAT IS STILL PRETTY COLD.

WITH QUESTIONABLE SNOW AMOUNTS THE NEXT FEW DAYS...TEMPERATURES ARE
IN A SLIGHT AMOUNT OF DOUBT...WITH EVEN A VERY MODEST SNOW COVER
KEEPING READINGS COLDER THAN THIS CURRENT FORECAST.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1216 PM CST MON DEC 2 2013

VFR THROUGH THE PD. WIND SPEED WILL INCREASE AROUND 10-15KTS TOWARD
THE END OF THE TAF PD AS A CDFNT PASSES THROUGH. HON MAY SEE SOME
MIXED PRECIP 11-14Z BUT CONFIDENCE IS LOW SO PROB30 WAS USED.


&&

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

$$

SHORT TERM...SALLY
LONG TERM...
AVIATION...HEITKAMP