Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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000
FXUS63 KFSD 240515
AFDFSD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1115 PM CST TUE DEC 23 2014

.UPDATE...
ISSUED AT 842 PM CST TUE DEC 23 2014

MINOR TWEAKS TO TEMPERATURES THIS EVENING...AS READINGS NOT
FALLING OFF AS QUICKLY AS FORECAST WITH THE PERSISTENT STRATUS AND
BRISK WINDS. BUMPED UP LOWS IN WESTERN AREAS A COUPLE OF DEGREES
BUT WITH UNCERTAINTY WHETHER CLOUDS WILL CLEAR (THEY ARE THE ONLY
AREA THAT HAS THAT CHANCE) DID NOT WANT TO RAISE TOO MUCH FROM
PREVIOUS FORECAST.

ONLY OTHER CHANGE OF NOTE WAS TO ADD MENTION OF DRIZZLE/FREEZING
DRIZZLE TO PARTS OF SOUTHWEST MN/NORTHWEST IA. LOSING THE COLDER
MID LEVEL MOISTURE IN SOME AREAS PER SATELLITE IMAGERY...BUT STILL
SOME SUBTLE LIFT THAT COULD RESULT IN DRIZZLE INSTEAD OF LIGHT
SNOW OR FLURRIES. TEMPERATURES STILL LARGELY ABOVE FREEZING THERE
AND NOT EXPECTED TO MOVE TOO MUCH...SO DO NOT EXPECT MUCH ICING...
BUT UNTREATED AREAS COULD GET A LITTLE SLICK WITH FORECAST TEMPS
STILL EXPECTED TO SLIP JUST BELOW FREEZING LATE TONIGHT.

&&

.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 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1112 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. 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 APPROACH 25 KNOTS FOR THE NEXT FEW HOURS
FOR KFSD AND KSUX.

&&

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

$$

UPDATE...JH
SHORT TERM...08
LONG TERM...
AVIATION...CHAPMAN


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