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000
FXUS63 KABR 031733 AAB
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1133 AM CST TUE DEC 3 2013

.UPDATE...REST OF TODAY
ONSET OF SNOW IS SLOWER THAN PREVIOUS FORECAST SO ADJUSTED WX/POP
GRIDS TO ACCOUNT FOR THIS. IT HAS BEEN SNOWING MUCH OF THE MORNING
ACROSS CENTRAL SD WHERE AROUND 2 INCHES HAS FALLEN IN THE PIERRE
AREA. SNOW HAS MOVED INTO THE JAMES VALLEY BUT HAS NOT ACCUMULATED
MUCH AS OF YET. SNOW WILL MOVE INTO THE FAR NORTHEAST CWA LATER
THIS AFTERNOON. MODELS STILL NOT IN GREAT AGREEMENT WITH SNOWFALL
PLACEMENT...BUT THINGS HAVE TRENDED A BIT FURTHER SOUTH. WILL
LEAVE HEADLINES AS IS AT THIS TIME. THE SOUTHWEST CWA MAY ACTUALLY
END UP GETTING THE MOST SNOW FOR THE TODAY PERIOD. AREAS NEAR THE
JAMES VALLEY AND POINTS EAST MAY NOW HAVE TO WAIT UNTIL LATER THIS
EVENING AND THROUGH THE OVERNIGHT BEFORE CONDITIONS BEGIN TO
DETERIORATE. THEN...GOING THROUGH WEDNESDAY...EXPECTING TO SEE
SOME WRAP AROUND SNOWFALL OVER THE EASTERN CWA. BASED ON MOST
RECENT MODEL INFO...HAVE ADJUSTED STORM TOTAL SNOW AMOUNTS A
BIT...WHICH INCLUDED LOWERING TOTALS FOR NORTHERN SD. BASICALLY
RIGHT NOW...GENERALLY HAVE 4 TO 6 INCHES ACROSS MUCH OF THE CWA.
STILL EXPECTING WINDS TO INCREASE FROM WEST TO EAST ACROSS THE CWA
THIS AFTERNOON THROUGH THE OVERNIGHT...CREATING AREAS OF BLOWING
SNOW AND REDUCED VISIBILITY WHICH WILL LAST THROUGH WEDNESDAY.


&&

.PREVIOUS DISCUSSION...

.SHORT TERM...TODAY AND WEDNESDAY

UNCERTAINTY REMAINS HIGH WITH THE WINTER STORM SYSTEM MOVING INTO
THE REGION TODAY. SNOWFALL HAS DEVELOPED ALONG A WARM AIR
ADVECTION WING ACROSS PARTS OF WESTERN AND SOUTH CENTRAL SOUTH
DAKOTA THIS MORNING. THE MAIN WAVE OF ENERGY WHICH WILL ENHANCE
SNOWFALL ACROSS THE NORTHERN CWA LATER THIS MORNING IS VISIBLE ON
WATER VAPOR IMAGERY...NOW SITUATED OVER SOUTHEAST IDAHO. SNOW
GROWTH ZONE OMEGA DOES INCREASE WITH THE SHORTWAVE PASSAGE...BUT
VALUES ARE MODEST. MODELS SHOW ANOTHER AREA OF QPF DEVELOPING
ALONG A FRONTOGENETIC ZONE FURTHER SOUTH LATER THIS AFTERNOON AND
EVENING...PERHAPS CLIPPING OUR SOUTHEASTERN CWA. WHILE MOST MODELS
ARE SHOWING THE TWO AREAS OF PRECIPITATION...THE TIMING AND
PLACEMENT STILL HAS NOT GAINED ANY CONSENSUS OR CONSISTENCY. USED
PERSISTENCE WITH MOST OF THE FORECAST THIS MORNING. THE MINOR
CHANGES MADE WERE TO DROP SNOW TOTALS SLIGHTLY ACROSS THE NORTHERN
CWA...AND THEN MAKE A SLIGHT INCREASE IN THE SNOW AMOUNTS ACROSS
THE SOUTHERN HALF OF THE CWA. THE HEADLINES STILL COVERED THE
SITUATION WELL...HOWEVER...TIMING IS SLIGHTLY SLOWER ACROSS THE
EASTERN CWA...SO MADE THE MINOR TIMING CHANGE. WINDS ARE STILL ON
TAP TO INCREASE THIS AFTERNOON AND CONTINUE INTO WEDNESDAY.
VISIBILITY ISSUES WILL LIKELY RESULT WHEN SNOW AND WIND COMBINE.
THE COLD AIR MASS IS STILL ON TRACK TO ADVECT INTO THE REGION
BEHIND THE LOW.


.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY

THE LONG TERM PERIOD WILL BE DOMINATED BY ARCTIC HIGH PRESSURE
SYSTEMS. INITIALLY...WITHIN THE COLD ADVECTION REGIME...MODELS
INDICATE STRATUS/STRATO CUMULUS WITHIN THE DENDRITIC GROWTH ZONE.
THERE WILL BE LITTLE LIFT SO JUST SOME LIGHT SNOW SHOWERS WILL
STRAGGLE BEHIND THE SURFACE LOW. MIX DOWN WINDS ARE ALSO AVERAGING
AROUND 15 TO 20 WITH GUSTS IN THE 30KT RANGE TO START THE PERIOD
OFF...HOWEVER THE GRADIENT WILL RELAX THROUGH EARLY THURSDAY.

FOR TEMPERATURES DURING THE INITIAL SURGE IN COLD AIR...H85
READINGS WILL AVERAGE BETWEEN -15C AND -20C...AND MIXING
WILL HELP TEMPER ANY TEMPERATURE EXTREMES. ITS QUESTIONABLE
WHETHER WINDS WILL DECOUPLE FOR FRIDAY MORNING WITH A GRADIENT
STILL ACROSS THE AREA. FOR FRIDAY AND SATURDAY...THE 1040MB
SURFACE HIGH WILL MOVE OVERHEAD REPRESENTING THE COLDEST TIMEFRAME
WITHIN THE EXTENDED. I WILL ASSUME EVERYONE WITHIN THE CWA WILL
HAVE ADEQUATE SNOW COVER TO INSULATE GROUND. THERE MAY BE SOME
MID/HIGH CLOUD MOVING INTO THE REGION HOWEVER...WHICH WILL TEMPER
EXPECTATIONS FOR EXTREME LOWS.

WARM ADVECTION IN THE LOW LEVELS MAY DEVELOP SATURDAY AS ONE AREA
OF ARCTIC HIGH PRESSURE PUSHES EAST...WHILE A SECOND DRIFTS DOWN
FROM CANADA. TEMPERATURES ARE WITHIN THE DENDRITIC GROWTH
ZONE...RESULTING IN STRATUS/LIGHT SNOW FOR SATURDAY.


&&

.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

IFR/MVFR CIGS WILL BE IN PLACE ACROSS MOST OF THE AREA THROUGH THE
TAF PERIOD. SNOWFALL WILL OCCUR OFF AND ON AS WELL...AND MAY
BECOME HEAVY AT TIMES. VSBYS WILL GENERALLY BE MVFR...BUT WILL
LIKELY FALL INTO THE IFR CATEGORY WITH THE HEAVIER BANDS OF SNOW.
LOOK FOR NORTHERLY WINDS TO INCREASE INTO THE 20 TO 35 MPH RANGE
TONIGHT...CONTINUING INTO THE MORNING HOURS ON WEDNESDAY.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER STORM WARNING UNTIL 6 PM CST /5 PM MST/ WEDNESDAY FOR
     BROWN-CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-MCPHERSON-POTTER-
     WALWORTH.

     WINTER STORM WARNING UNTIL 6 PM CST WEDNESDAY FOR DAY-MARSHALL-
     ROBERTS.

     WINTER WEATHER ADVISORY UNTIL 6 PM CST /5 PM MST/ WEDNESDAY FOR
     BUFFALO-HAND-HUGHES-HYDE-JONES-LYMAN-SPINK-STANLEY-SULLY.

     WINTER WEATHER ADVISORY UNTIL 6 PM CST WEDNESDAY FOR CLARK-
     CODINGTON-DEUEL-GRANT-HAMLIN.

MN...WINTER STORM WARNING UNTIL 6 PM CST WEDNESDAY FOR BIG STONE-
     TRAVERSE.

&&

$$
UPDATE...TMT
SHORT TERM...SERR
LONG TERM...CONNELLY
AVIATION...PARKIN

WEATHER.GOV/ABERDEEN