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000
FXUS63 KUNR 031628
AFDUNR

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
928 AM MST TUE DEC 3 2013

.UPDATE...
ISSUED AT 919 AM MST TUE DEC 3 2013

LATEST KUDX RADAR SHOWS HEAVIER SNOW CONTINUING ACROSS NORTHWEST
INTO CENTRAL SOUTH DAKOTA. GREATEST SNOW AMOUNTS HAVE BEEN ACROSS
PORTIONS OF CROOK COUNTY THROUGH BUTTE INTO NORTHERN MEADE
COUNTIES OF 6 TO 10 INCHES OF ACCUMULATION. LATEST MODEL GUIDANCE
HAS A SOUTHWARD SHIFT OF THE ACTIVITY THIS AFTERNOON. SNOW OVER
NW SD IS EXPECTED TO WANE THROUGH TODAY...WHILE SNOW IS EXPECTED
TO DEVELOP ACROSS SOUTHERN PORTIONS OF THE CWA...ESPECIALLY SOUTH
CENTRAL SD. THIS SNOWFALL WILL CONTINUE INTO TONIGHT WITH 2 TO 5
INCHES OF ACCUMULATION BY WEDNESDAY MORNING. HAVE ISSUED A WINTER
WEATHER ADVISORY FOR SOUTH CENTRAL SD COUNTIES UNTIL 06Z
WEDNESDAY WHEN WINDS BEGIN TO TAPER OFF OVER THE AREA. WINDS
ACROSS THE REST OF THE CWA...EXCEPT THE NORTHEAST WYOMING
PLAINS...HAVE BEEN SLOW TO DEVELOP. LATEST MODELS ARE SHOWING THIS
DELAY UNTIL THIS AFTERNOON OR THIS EVENING...SO HAVE ADJUSTED WSW
WORDING.

&&

.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
ISSUED AT 416 AM MST TUE DEC 3 2013

CURRENT SURFACE ANALYSIS SHOWS INITIAL ARCTIC BOUNDARY
NOW SOUTH OF THE CWA....WITH COLDER AIR SLOWLY SLIDING SOUTH INTO
THE AREA AND WINDS GRADUALLY INCREASING. LEADING EDGE OF MAIN ARCTIC
AIR MASS IS FURTHER NORTH AND WEST ACROSS NORTHERN AND WESTERN MT
AND WILL MAKE ITS WAY INTO THE AREA LATER TODAY. UPPER LEVEL
ANALYSIS SHOWS LOW OVER THE NORTHERN ROCKIES...MOVING
EAST-SOUTHEAST. STRONG UPPER JET IN PLACE TO THE SOUTH OF THE LOW
FROM OR TO WY AND CO. STRONG SHORTWAVE ENERGY ROTATING AROUND THE
LOW IS MOVING ACROSS EASTERN MT...NORTHERN WY...AND THE WESTERN
DAKOTAS. KUDX RADAR SHOWING POST FRONTAL BAND OF MOSTLY SNOWFALL
MOVING ACROSS FAR NORTHEASTERN WY AND PORTIONS OF NORTHWESTERN SD.
THERE IS SOME HEAVIER SNOW WITHIN THIS BAND THAT HAS MAINLY IMPACTED
BUTTE AND NORTHERN MEADE COUNTIES SO FAR. UP TO A FEW INCHES OF SNOW
HAS LIKELY FALLEN IN THESE AREAS OVERNIGHT. FURTHER SOUTH AND
WEST...SOME LIGHTER PCPN HAS FALLEN OVER MOST OF THE BLACK HILLS AND
PLAINS TO THE EAST. CONDITIONS HAVE BEEN MOSTLY DRY TO THIS POINT
ACROSS FAR SOUTHERN SD. A LITTLE BIT OF FREEZING DRIZZLE/MIXED PCPN
HAS ALSO BEEN NOTED ON OBSERVATIONS/RADAR...INCLUDING IN THE RAP
AREA. TEMPS RANGE FROM THE UPPER TEENS OVER FAR NORTHWESTERN SD TO
THE LOWER 30S ACROSS FAR SOUTHWESTERN SD. HIGHS TODAY WILL BE
EARLY...WITH STEADY TO SLOWLY FALLING TEMPS THROUGH THE
DAY...ESPECIALLY FALLING IN THE AFTERNOON. WINDS ARE NORTHEASTERLY
IN MOST LOCATIONS AND BECOMING WINDY ACROSS NORTHERN AND WESTERN
AREAS.

PREVIOUS FORECAST PACKAGE CONTINUES TO LOOK GOOD SO FAR...WITH
MAINLY MINOR MODIFICATIONS MADE TO PCPN CHANCES...SNOWFALL
TOTALS...AND WIND. THE BIGGEST CHANGES WERE TO THE WINDS FOR AT
LEAST TODAY AS IT LOOKS LIKE THE STRONGER WINDS WILL HOLD OFF UNTIL
LATER THIS MORNING AND AFTERNOON WHEN THE MAIN SURGE OF ARCTIC AIR
PUSHES IN. EVEN AT THAT...WINDS GENERALLY DO NOT LOOK QUITE AS
STRONG THROUGH WEDNESDAY AS WAS EXPECTED...SO HAVE TAPERED THEM DOWN
A BIT FOR TONIGHT AND WEDNESDAY AS WELL. THERE WILL STILL BE MORE
THAN ENOUGH WIND TO PRODUCE AREAS OF BLOWING AND DRIFTING SNOW OVER
THE WARNING AREA AND INTO THE ADVISORY AREA. WILL NOT MAKE ANY
CHANGES TO CURRENT HEADLINES AS THEY LOOK TO BE IN GOOD SHAPE...AT
LEAST AT THIS POINT.

STILL LOOKS LIKE MOST OF THE ACCUMULATING SNOW ACROSS THE AREA WILL
FALL THROUGH THE DAYTIME HOURS TODAY...WITH LIGHTER SNOW TONIGHT
INTO WEDNESDAY...AS MAIN UPPER LOW PASSES ACROSS THE NORTHERN
PLAINS. HAVE INCREASED SNOWFALL AMOUNTS ACROSS NORTHWESTERN SD A BIT
MORE AS THE MODELS CONTINUE TO PINPOINT THIS AREA FOR THE HEAVIEST
SNOW THROUGH THE MORNING AND EARLY AFTERNOON HOURS...ESPECIALLY FAR
NORTHWESTERN SD. GENERAL 6 TO 10 INCH AMOUNTS ARE EXPECTED FROM
NORTHERN BUTTE...NORTHERN MEADE...AND MUCH OF ZIEBACH CO...NORTHWARD
TO THE ND BORDER. A FEW LOCATIONS OVER FAR NORTHWESTERN SD COULD
RECEIVE AROUND A FOOT WITH SNOWFALL RATIOS NEAR 20/1 EXPECTED TODAY.
FURTHER SOUTH AND WEST ACROSS THE WARNING AREA...FROM NORTHEASTERN
WY INTO THE NORTHERN BLACK HILLS AREA...SNOWFALL AMOUNTS OF 3 TO 7
INCHES ARE EXPECTED BY WEDNESDAY. LOCALLY HIGHER AMOUNTS ARE
POSSIBLE OVER FAVORED AREAS OF THE NORTHERN BLACK HILLS AND BEAR
LODGE MTS. LOCATIONS IN THE ADVISORY AREA WILL MOSTLY RECEIVE 2 TO 4
INCHES OF SNOW. A COUPLE OF INCHES OF SNOW IS POSSIBLE IN SOME
AREAS OVER FAR SOUTHERN SD LATE TODAY INTO EARLY WEDNESDAY AS
SECONDARY WAVE MOVES ACROSS THE CENTRAL ROCKIES AND PLAINS...THOUGH
SHORT RANGE MODELS DIFFER ON THAT POSSIBILITY.

AFTER THE SNOW ENDS...THE BITTER COLD WILL REMAIN WITH HIGHS ON
WEDNESDAY IN THE SINGLE DIGITS AND LOWER TEENS...AND WIND CHILLS
WELL BELOW ZERO. LOWS WEDNESDAY NIGHT WILL BE BELOW ZERO WITH WIND
CHILLS TO NEAR 30 BELOW. HEADLINES WILL LIKELY BE NEEDED FOR THIS
WHEN THAT TIME ARRIVES.

&&

.LONG TERM...THURSDAY THROUGH MONDAY
ISSUED AT 416 AM MST TUE DEC 3 2013

THE REGION WILL REMAIN DEEPLY ENTRENCHED IN COLD ARCTIC AIR FOR
THE FORESEEABLE FUTURE WITH A LARGE UPPER TROF COVERING THE CNTRL
CONUS. THE BEST CHANCE FOR ANY SNOW WILL BE IN THE SATURDAY/SUNDAY
TIME FRAME AS AN UPPER LEVEL DISTURBANCE BRINGS A PERIOD OF WEAK
WARM ADVECTION ATOP THE COLD DOME OF ARCTIC AIR.

&&

.AVIATION...FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING
ISSUED AT 416 AM MST TUE DEC 3 2013

ARCTIC AIR WILL CONTINUE POURING INTO THE REGION TODAY AND
TONIGHT...BRINGING GUSTY N/NW WINDS ESPECIALLY ON THE PLAINS OF
NWRN AND WCNTRL SD. SNOW WILL ALSO CONTINUE TO BRING IFR TO LIFR
CONDITIONS ESPECIALLY NORTH OF INTERSTATE 90. SOUTH OF INTERSTATE
90...SOME LIGHT SNOW WILL FALL BUT IFR/LIFR CONDITIONS WILL BE
PREDOMINANTLY DUE TO LOW STRATUS AND FOG.


&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 11 PM MST /MIDNIGHT CST/ WEDNESDAY
     FOR SDZ043-044-046-047-049.

     WINTER STORM WARNING UNTIL 5 PM MST WEDNESDAY FOR SDZ001-002-
     012>014-024-025-072-073.

     WINTER WEATHER ADVISORY UNTIL 5 PM MST WEDNESDAY FOR SDZ026-
     028>032-074.

WY...WINTER STORM WARNING UNTIL 11 AM MST WEDNESDAY FOR WYZ054-056-
     057-071.

     WINTER WEATHER ADVISORY UNTIL 5 PM MST WEDNESDAY FOR WYZ055-058.

&&

$$

UPDATE...13
SHORT TERM...26
LONG TERM...JOHNSON
AVIATION...JOHNSON