FXUS63 KABR 232006
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
206 PM CST WED DEC 23 2009

.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT
MAIN FORECAST CHALLENGE IS TIMING THE ONSET OF THE SNOW THIS
EVENING AND THE SUCCESSIVE WAVES CIRCULATING AROUND THE MAIN LOW.

CURRENTLY RADAR IMAGERY IS SHOWING STEADY RETURNS OVER THE WESTERN
PART OF THE STATE...WITH LIGHT SNOW BEING REPORTED. THERE ARE
STILL LOW CLOUDS AND PATCHY RADAR RETURNS OVER THE EASTERN AND
CENTRAL PART OF THE STATE THAT MAY BE INTERPRETED AS LIGHT
FREEZING DRIZZLE. HAVE CONTINUED THE NOWCAST FOR FZDZ THROUGH
2130Z FOR THE EASTERN COUNTIES. THE MAIN PUSH OF SNOW FROM THE
SOUTH IS JUST NORTH OF KFSD. AS THIS MOVES FARTHER NORTH OVER THE
NEXT FEW HOURS FZDZ WILL GIVE WAY TO ALL SNOW ACROSS THE STATE.

THE WINTER STORM WARNING IS STILL IN EFFECT AND MODELS AGREE ON
THE GENERAL DEVELOPMENT OF THE WINTER STORM SYSTEM THOUGH THE
PRECIP WILL LIKELY LINGER A LITTLE LONGER THAN ORIGINALLY THOUGHT.
EXPECT SNOW TO WIND DOWN SATURDAY AFTERNOON AND EVENING. THE NEW RUN OF
THE ECMWF IS ALSO CONSISTENT IN SHOWING A STRONGER UPPER WAVE
DROPPING OUT OF THE NORTHWEST THURSDAY MORNING. THIS WAVE THEN
MERGES WITH THE MAIN UPPER LOW. INTERESTINGLY THERE ARE STILL NO
PAST MODEL ANALOGS FOR THIS SYSTEM SO WE ARE EFFECTIVELY IN NEW
TERRITORY THAT THE MODELS SEEM TO BE HANDLING WELL.

THE FORECAST IS STILL ON TRACK WITH WIDESPREAD SNOWFALL BEGINNING
THIS EVENING. HOWEVER THERE WILL BE BREAKS IN THE PRECIP TOMORROW
AS THE SYSTEM REDEVELOPS AFTER MERGING WITH THE H7 LOW TO THE
NORTH AND BEGINS TO ROTATE NORTHWEST. DURING THIS BREAK THE WSW
WILL MOST LIKELY NEED TO BE UPGRADED TO A BLIZZARD WARNING TO
REFLECT THE INCREASED THREAT OF WHITEOUT CONDITIONS. WINDS START
TO INCREASE FROM WEST TO EAST THURSDAY BUT STRONGEST SUSTAINED
WINDS WILL BE ACROSS THE EAST. BY LATE THURSDAY NIGHT WIND GUSTS UP TO
40 MPH ARE POSSIBLE.

.LONG TERM...SATURDAY THROUGH WEDNESDAY
WHEN TO END PRECIPITATION CHANCES FROM THE CURRENT WEATHER SYSTEM
IS THE MAIN FORECAST ISSUE IN THE EXTENDED. VIRTUALLY ALL MODELS
SHOW WRAP AROUND SNOW CONTINUING THROUGH THE DAY ON SATURDAY...EVEN
WITH A SLIGHT CHANCE ON SATURDAY NIGHT. THERE MAY BE SOME LIGHT
SNOW ON SUNDAY BEFORE A HIGH PRESSURE BUILDS INTO THE REGION FROM
THE NORTHWEST. AN UPPER LEVEL RIDGE WILL ACCOMPANYING THE HIGH
PRESSURE...WHICH WOULD NORMALLY LEAD TO WARMER TEMPERATURES.
HOWEVER WITH NEW SNOW COVER...WILL LEAVE TEMPERATURES BELOW
NORMAL. 

&&

.AVIATION...
IFR CEILINGS ARE EXPECTED CONTINUE THROUGH THURSDAY...ALONG WITH
1 TO 5SM IN FOG. LIGHT SNOW IS EXPECTED TO DEVELOP LATER THIS
AFTERNOON AND EARLY EVENING FROM SOUTH TO NORTH AFFECTING ALL OF
THE TAF LOCATIONS. THE SNOW WILL INCREASE IN INTENSITY THROUGH
TONIGHT WITH VISIBILITIES FALLING TO BELOW 1/2SM AT TIMES. THERE
MAY BE SOME BREAKS IN THE SNOW ON THURSDAY AFTERNOON...HOWEVER IFR
CONDITIONS WILL LIKELY CONTINUE.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER STORM WARNING FROM 6 PM CST /5 PM MST/ THIS EVENING TO 6 
     AM CST /5 AM MST/ SATURDAY FOR BROWN-BUFFALO-CAMPBELL-CLARK-
     CODINGTON-CORSON-DAY-DEUEL-DEWEY-EDMUNDS-FAULK-GRANT-HAMLIN-
     HAND-HUGHES-HYDE-JONES-LYMAN-MARSHALL-MCPHERSON-POTTER-
     ROBERTS-SPINK-STANLEY-SULLY-WALWORTH.

MN...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM CST SATURDAY 
     FOR BIG STONE-TRAVERSE.

&&

$$
SHORT TERM...WISE
LONG TERM...SD
AVIATION...SD

WEATHER.GOV/ABERDEEN