Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 232345
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
545 PM CST TUE DEC 23 2014

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 349 PM CST TUE DEC 23 2014

FORCING CONTINUES TO DWINDLE THROUGH THE AFTERNOON AND EVENING WITH
DRIER AIR WORKING IN ALOFT. THIS SHOULD CONTINUE TO BRING
DIMINISHING LIGHT SNOWFALL FROM WEST TO EAST THIS EVENING. MAYBE AN
ADDITIONAL QUARTER INCH OR SO OF SNOW IN FAR SOUTHEAST NORTHWEST
IOWA BUT WITH TEMPERATURES IN THE MID 30S NOT EXPECTING TOO MANY
PROBLEMS. WITH CLOUDS HANGING TOUGH ALL NIGHT BUMPED LOWS UP JUST A
TOUCH BUT THERE WILL BE SOME DECENT COLD AIR ADVECTION THROUGH THE
NIGHT BUT AT THIS TIME ONLY ANTICIPATING A CHANCE OF THE CLOUD COVER
BREAKING OUT IN CENTRAL PARTS OF SOUTH DAKOTA. SO WENT COLDEST ON
LOWS THERE.

THERE COULD BE SOME SURPRISE SUNSHINE ON WEDNESDAY MORNING...NOT A
GREAT CHANCE...BUT WITH THE WET GROUND SUSPECT THAT ANY AREAS THAT
CAN SEE SOME SUNSHINE IN THE MORNING WOULD LIKELY SEE STRATUS
REDEVELOPMENT AGAIN WITHIN A COUPLE HOURS  GIVEN FAIRLY MOIST GROUND
LEVEL AIR MASS AN STILL A BIT OF AN INVERSION AROUND 900MB. STRONG
WINDS TONIGHT WILL BE A MORE STANDARD 10 TO 20 MPH ON WEDNESDAY WITH
HIGHS FROM THE UPPER 20S TO MID 30S ACROSS THE AREA.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 349 PM CST TUE DEC 23 2014

PATTERN IS EXPECTED TO SLOWLY EVOLVE TOWARDS A COOLER PATTERN AS
ZONAL FLOW TRANSITIONS MORE TOWARDS A NORTHWEST FLOW AS THE HUDSON
BAY LOW TRIES TO RE-ESTABLISH ITSELF TOWARDS THE NEW YEAR.
RELATIVELY MILD PATTERN TO START OFF WITH FOR CHRISTMAS EVE INTO
WITH 925 HPA TEMPS WARMING TO NEAR 0C DURING THE DAY ON CHRISTMAS
DAY.  CLOUDS AND LOW SUN ANGLE WILL LIMIT WARMING POTENTIAL
SOME...BUT STILL SHOULD SEE TEMPERATURES 10-15 DEGREES ABOVE NORMAL
ON BOTH THE LOWS AND HIGHS.

NEXT SYSTEM COMES IN ON THURSDAY AS A PAIR OF OPEN PHASED WAVES.
MODELS ARE SUGGESTING THAT THE NORTHERN WAVE WILL HAVE VERY LIMITED
AMOUNTS OF MOISTURE AS THE SOUTHERN SYSTEM INTENSIFIES.  FORECAST
SOUNDINGS SUGGEST A LACK OF SATURATION ALOFT AS THE WAVE SHIFTS EAST
ACROSS THE AREA...MAKING IT DIFFICULT TO GET ICE IN THE COLUMN.  AS
SUCH...HAVE LIKELY POPS ACROSS CENTRAL SOUTH DAKOTA TRANSITIONING TO
CHANCE POPS FURTHER TO THE EAST.  ANY PRECIPITATION WITH THIS SYSTEM
APPEARS TO BE FAIRLY LIGHT.

COOLER AIR STARTS TO FILTER INTO THE REGION ON THE BACKSIDE OF THE
WAVE ON SATURDAY INTO SUNDAY. SECOND SYSTEM IS EXPECTED TO WORK
THROUGH THE REGION ON MONDAY...WITH POTENTIALLY EVEN COOLER AIR
WORKING INTO THE REGION BEHIND THIS SYSTEM.  WHILE THE GFS IS COOLER
BY ABOUT 5 DEGREES C THAN THE ECMWF...IT IS LESS WINDY THAN THE GFS.
 FOR NOW...SIDED TOWARDS THE COOLER GUIDANCE AND RAISED WINDS IN THE
OUTER PERIODS.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 545 PM CST TUE DEC 23 2014

CEILINGS ACROSS THE AREA WILL BE RIDING THE EDGE OF THE MVFR AND
IFR RANGE THROUGH MUCH OF THE NIGHT AND EARLY MORNING HOURS FOR
TAF SITES. CIGS MAY VERY WELL REMAIN JUST ON THE MVFR SIDE WITH
INCREASED MIXING TONIGHT...BUT SUBSIDENCE WITH APPROACHING RIDGE
AXIS WILL LIKELY PUSH DOWN INTO THE UPPER END OF IFR RANGE BY VERY
LATE NIGHT OR EARLY WEDNESDAY MORNING. LOWEST CEILINGS WILL LIKELY
RAISE A BIT WITH MIXING DURING BY LATE MORNING OR MIDDAY. APPEARS
AS IF SHOULD SEE BREAK INTO THE VFR CEILING RANGE AS WINDS FLOW
ALOFT PICKS UP INCREASING DEGREE OF WESTERLY COMPONENT AROUND KHON
BY MIDDAY...AND MID TO LATE AFTERNOON AT KFSD AND KSUX. IN
ADDITION TO CEILINGS...MAY SEE A FEW SURFACE WIND GUSTS AROUND 25
KNOTS FOR THE NEXT SEVERAL HOURS.

&&

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

$$

SHORT TERM...08
LONG TERM...
AVIATION...CHAPMAN


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