FXUS63 KABR 250236
AFDABR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
836 PM CST THU DEC 24 2009

.UPDATE...
BLIZZARD WARNING CONTINUES TONIGHT AND IS STARTING TO LOOK LIKE A
GOOD BET AS VISIBILITY IN HEAVIEST RETURNS ON RADAR ARE DROPPING
TO 1/4 MILE AND THE HEAVIEST RADAR RETURNS ARE MOVING THIS WAY.
EXPECT THE EAST PART OF THIS AREA TO BE IN BLIZZARD CONDITIONS
EASILY BY MIDNIGHT WITH THE CONDITIONS SPREADING EAST THROUGH THE
NIGHT. HAVE INCREASED SNOW FALL TOTALS A LITTLE FOR TOMORROW AND
TOMORROW NIGHT AND HAVE MADE SOME ADJUSTMENTS TONIGHT TO WORK
BETTER WITH SURROUNDING OFFICES. NONE OF THE CHANGES WAS BIG OR
DRAMATIC BECAUSE SITUATION IS UNFOLDING WELL AS FORECAST WITH ONLY
THE HEAVY SNOW BEING A LITTLE SLOW. THE MESSAGE REMAINS THAT LATER
THIS EVENING TRAVEL IN MUCH OF EASTERN AND CENTRAL SOUTH DAKOTA
WILL BE VERY DIFFICULT OR IMPOSSIBLE AS AROUND A FOOT OF SNOW
BLANKETS THE AREA. TEMPERATURES WERE ADJUSTED DOWN A LITTLE AS
WELL. CURRENT TEMPERATURES WERE NEARING THE OVERNIGHT LOWS SO DID
DROP OVERNIGHT LOW A FEW DEGREES.

&&
.PREV DISCUSSION...
.SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT

MAIN FORECAST CHALLENGE CONTINUES TO BE TIMING OF WORST CONDITIONS
ASSOCIATED WITH THE CURRENT SYSTEM.

CURRENTLY THOUGH RADAR INDICATES LIGHT ECHOES ACROSS THE EASTERN
PART OF THE REGION MOST SITES ARE PRECIP FREE. THE SYSTEM IS STILL
WRAPPING UP OVER THE SOUTHERN PLAINS AND DRAWING MOISTURE OFF THE
GULF. THE INITIAL FRONT IS NEAR WEST CENTRAL MN AND SEEMS TO BE
STALLING. HEAVIEST PRECIP BANDS ARE STREAMING OVER WESTERN MN. THERE
HAS BEEN A SIGNIFICANT TEMPERATURE FREE FALL BEHIND THE FRONT WITH
TEMPS NOW IN THE SINGLE DIGITS FROM MARSHALL COUNTY DOWN TO
WATERTOWN AND POINTS WESTWARD.

THE MODELS HAVE BEEN VERY CONSISTENT IN MOVING THE SFC LOW
SLOWLY NORTH TONIGHT AFTER THE H7 SOUTHERN STREAM LOW MERGES WITH
THE NORTHERN TROUGH. TIMING OF ANY BANDING RESULTING FROM
CONVECTION AS THE LOW MOVES NORTH OR TIMING THE SHORTWAVES WRAPPING
AROUND THE TROWAL IS PRETTY MUCH IMPOSSIBLE. HOWEVER OMEGA VALUES
INDICATE HEAVIER SNOWFALL FROM MIDNIGHT FRIDAY THROUGH MIDNIGHT
SATURDAY. EXPECT MOST OF THE STORM TOTAL SNOW OF 9 TO 16 INCHES TO
FALL DURING THIS TIME WITH HIGHEST AMOUNTS EAST OF THE JAMES
VALLEY. WINDS WILL INCREASE DURING THIS TIME OUT OF THE NORTHWEST
TO 25 TO 40 MPH WITH HIGHER GUSTS. THESE WINDS SHOULD KEEP THE
SNOW RATIOS DOWN TO AROUND 9 OR 10:1 EVEN WITH THE COOLER TEMPS.
UNFORTUNATELY THE OTHER EFFECT OF THESE WINDS WILL BE WIND CHILLS
MAKING IT FEEL LIKE 20 TO 34 BELOW ZERO.

UPGRADED THE WSW TO A BZW NOW THOUGH JUST AS EASILY COULD HAVE
CANCELLED ALL WARNINGS UNTIL MIDNIGHT. HOWEVER SINCE IT IS THE
SAME SYSTEM THE DESIRE WAS TO KEEP SOME CONTINUITY IN THE WARNING
PROCESS. THEREFORE WORDED THE STATEMENT TO REFLECT EXPECTED
BLIZZARD ONSET BETWEEN MIDNIGHT AND CHRISTMAS MORNING. REDUCED
VISBYS IN BLOWING SNOW ARE EXPECTED TO LAST THROUGH SATURDAY
MORNING WITH SNOW TAPERING OFF SATURDAY EVENING.

.LONG TERM...SUNDAY THROUGH WEDNESDAY
UPPER LOW FROM THE SHORT TERM PERIOD WILL BE MOVING EAST INTO THE
GREAT LAKES REGION AT THE START OF THE EXTENDED PERIOD. MODELS ARE
SUGGESTING ENOUGH MOISTURE AND WEAK LIFT WILL BE PRESENT STILL TO
MAINTAIN AT LEAST A THREAT FOR FLURRIES SO HAVE INSERTED THIS INTO
THE FORECAST FOR SUNDAY. UPPER LEVEL RIDGING THEN TAKES PLACE
ACROSS THE UPPER MIDWEST WITH WARMING MID LEVEL TEMPERATURES. WITH
A FRESH DEEP SNOW COVER ACROSS MUCH OF THE UPPER MIDWEST DURING
THIS TIME...DO NOT EXPECT MUCH OF A WARM UP AT THE SURFACE. AFTER
THE SCT FLURRIES ON SUNDAY...THE REST OF THE EXTENDED PERIOD LOOKS
DRY. IT APPEARS THAT BY THE END OF NEXT WEEK THERE EXISTS THE
POTENTIAL FOR ANOTHER ARCTIC AIR MASS TO MOVE SOUTH ACROSS THE
PLAINS AS EC AND GFS BRING 850MB TEMPS DOWN TO AROUND -20C.

&&

.AVIATION...
IFR CONDITIONS ARE ARE SPREADING ACROSS THE AREA FORM THE EAST
TONIGHT AS A MAJOR WINTER STORM APPROACHES THE AREA. KABR AND KATY
ARE ALREADY IFR AS SNOW FALL INCREASES. THIS SNOWFALL WILL SPREAD
WEST AND KMBG AND KPIR WILL DROP TO IFR LATER THIS EVENING.
CONDITIONS WILL REMAIN IFR TOMORROW WITH STRONG SURFACE WIND AND
HEAVY SNOW FALL RATES.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...BLIZZARD WARNING UNTIL NOON CST /11 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...BLIZZARD WARNING UNTIL NOON CST SATURDAY FOR BIG STONE-TRAVERSE.

&&

$$
UPDATE...KEEFE
SHORT TERM...WISE
LONG TERM...TMT
AVIATION...KEEFE

WEATHER.GOV/ABERDEEN