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000
FXUS63 KABR 061737 AAC
AFDABR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1137 AM CST FRI DEC 6 2013

.UPDATE...
SEE BELOW FOR AN UPDATED AVIATION FORECAST DISCUSSION.

ARCTIC HIGH PRESSURE CONTINUES TO DOMINATE THE NORTHERN PLAINS
WITH CURRENT OBS SHOWING TEMPERATURES BETWEEN 5 BELOW TO 10 BELOW
ZERO. BASED ON THE PAST FEW RUNS OF THE GFS LAMP GUIDANCE...HIGHS
TODAY WILL LIKELY REACH THE SINGLE DIGITS ON EITHER SIDE OF ZERO
AT BEST. WITH A VAST MAJORITY OF THE NORTHERN PLAINS UNDER CLEAR
SKIES...HAVE SIGNIFICANTLY LOWERED SKY GRIDS THROUGH THIS EVENING.
THE CAVEAT IS THE MISSOURI RIVER VALLEY WHERE WARM OPEN WATER IS
CREATING CLOUDS...FOG...AND PERHAPS SOME LIGHT SNOWFALL.


&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SUNDAY
CURRENT SURFACE ANALYSIS SHOWS A HIGH PRESSURE RIDGE EXTENDING OUT
OF CANADA ACROSS MONTANA AND INTO WESTERN SOUTH DAKOTA. OUR CWA
STILL REMAINS TO THE NORTHEAST OF THE RIDGE...WITH A MODERATE TO
WEAK PRESSURE GRADIENT OVERHEAD. ALMOST ALL CWA OBS ARE REPORTING
WINDCHILL VALUES TWENTY FIVE BELOW ZERO OR COLDER THIS MORNING.
ALSO...WE ARE AGAIN SEEING FLURRIES AROUND THE PIERRE AREA DUE TO
THE EFFECTS OF LAKE OAHE.

TEMPERATURES THIS AFTERNOON ARE ONLY EXPECTED TO RANGE FROM THE
SINGLE DIGITS BELOW TO THE SINGLE DIGITS ABOVE ZERO. THE RIDGE
WILL GRADUALLY SAG SOUTHEAST...HOWEVER WIND SPEEDS THROUGH THE
AFTERNOON WILL REMAIN IN THE 10 TO 15 MPH RANGE THROUGH THE
DAY...ALLOWING FOR WIND CHILL VALUES IN THE 15 BELOW TO 25 BELOW
RANGE. WENT BACK AND FORTH OVER WHAT TO DO WITH THE WIND CHILL
ADVISORY TONIGHT THROUGH SATURDAY MORNING...MAINLY CONCERNING THE
SOUTHWEST CWA. THIS REGION WILL EVENTUALLY BE UNDER WEAK MID LEVEL
WARM AIR ADVECTION BY SATURDAY MORNING...AND EXPECT ASSOCIATED
CLOUD COVER TO GRADUALLY SPREAD OVER THIS REGION. AT THE SAME TIME
THE BROAD AREA OF HIGH PRESSURE WILL EXTEND FROM NORTHWEST TO
SOUTHEAST ACROSS THE STATE AND THIS WILL MEAN THAT WINDS WILL GO
FAIRLY LIGHT ACROSS CENTRAL SOUTH DAKOTA AT SOME TIME OVERNIGHT.
GIVEN THIS COMBINATION...AN ARGUMENT COULD BE MADE THAT THE WIND
CHILL ADVISORY SHOULD BE EXPIRED ACROSS THIS AREA BEFORE THE
REMAINING CWA. HOWEVER...STILL EXPECTING TEMPERATURES TO BE JUST
AS COLD OR COLDER THAN THE PREVIOUS NIGHTS...AND IT WILL BE
DIFFICULT TO PINPOINT THE EXACT LINE OF GREATER THAN OR LESS THAN
5 MPH WINDS...SO FOR SIMPLICITY...OPTED TO JUST EXTEND THE ENTIRE
ADVISORY INTO SATURDAY MORNING. THE NORTHERN AND EASTERN CWA WILL
EASILY DROP INTO THE ADVISORY CRITERIA.

SATURDAY AND SUNDAY THE UPPER LEVEL PATTERN TRANSITIONS FROM NEAR
ZONAL TO SOUTHWEST AS A POSITIVELY TILTED TROUGH MOVES ACROSS THE
WESTERN CONUS. THE GREATEST MOISTURE WILL REMAIN SOUTH OF OUR
CWA...HOWEVER THERE SHOULD BE ENOUGH SATURATION AND ISENTROPIC
LIFT TO PRODUCE LIGHT SNOWFALL ACROSS THE CWA ON SUNDAY. IT IS
GENERALLY LOOKING LIKE LESS THAN AN INCH OF SNOW...WITH PERHAPS
HAVE FEW SLIGHTLY HIGHER SNOWFALL AMOUNTS ACROSS THE SOUTHEAST
CWA.


.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
A BROAD UPPER LEVEL TROUGH WILL BE OVER THE PLAINS WHEN THE
PERIOD STARTS. A SERIES OF SHORTWAVES WILL TRACK ACROSS THE REGION
IN ASSOCIATION WITH THIS TROUGH...WITH THE STRONGEST WAVES COMING
THROUGH LATE SUNDAY NIGHT/EARLY MONDAY...AND ANOTHER MONDAY NIGHT
INTO EARLY TUESDAY...WITH ONE FINAL WAVE MOVING THROUGH ON
WEDNESDAY.

AN AREA OF PRECIPITATION LOOKS TO JUST BE SKIRTING THE EASTERN CWA
SUNDAY NIGHT...BUT EXITS QUICKLY AS HIGH PRESSURE BEGINS TO PUSH
IN FROM THE WEST. THE HIGH WILL NOT STICK AROUND VERY
LONG...GETTING PUSHED SOUTHWARD BY A CLIPPER THAT IS FORECAST TO
TRACK ACROSS THE NORTHERN PLAINS MONDAY AND MONDAY NIGHT. AT THIS
TIME...IT DOES NOT LOOK LIKE MUCH PRECIPITATION WILL OCCUR WITH
THIS SYSTEM...BUT WILL KEEP SMALL POPS IN AS SOME LIGHT SNOW IS
POSSIBLE. THE REMAINDER OF THE PERIOD LOOKS TO BE DRY AS HIGH
PRESSURE WILL BE THE DOMINANT FEATURE. BY WEDNESDAY NIGHT...SOME
DIFFERENCES BEGIN TO SHOW UP IN THE MODELS...WITH THE GFS BRINGING
A STRONGER LOW ACROSS THE REGION THAN THE ECMWF. NOT MUCH IN THE
WAY OF UPPER SUPPORT AT THIS TIME...SO WILL JUST LEAVE THE TIME
PERIOD DRY.

COLD AIR WILL REMAIN IN PLACE UNTIL WEDNESDAY/WEDNESDAY
NIGHT...WITH DAYTIME HIGHS IN THE SINGLE DIGITS AND TEENS. SUBZERO
OVERNIGHT LOWS ARE EXPECTED SUNDAY NIGHT...MONDAY NIGHT AND
TUESDAY NIGHT. BY THE VERY END OF THE PERIOD...SOME WARMER AIR
LOOKS TO MOVE IN WITH THURSDAYS TEMPERATURES BACK TO NEAR NORMAL.


&&

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

UNDER A CLEAR SKY AND LIGHT WINDS VFR CIG/VISBY CONDITIONS WILL
PREVAIL ACROSS THE AREA THIS AFTERNOON THROUGH SATURDAY MORNING.
THE CAVEAT IS ACROSS PORTIONS OF THE MISSOURI RIVER
VALLEY...INCLUDING THE KPIR TERMINAL...WHERE THE WARM OPEN WATER OF
LAKE OAHE IS CREATING A LAKE EFFECT BAND OF IFR CLOUDS AND SNOW.
ONCE BOUNDARY LAYER WINDS GO LIGHT AND VARIABLE LATER THIS
EVENING...THE BAND OF CLOUDS AND SNOW /AND IFR WEATHER/ SHOULD
END AT THE KPIR TERMINAL...WITH PERHAPS JUST A SCATTERED TO BROKEN
LAYER OF MID/HIGH CLOUDS STREAMING ACROSS THE REGION.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...WIND CHILL ADVISORY UNTIL 9 AM CST /8 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...WIND CHILL ADVISORY UNTIL 9 AM CST SATURDAY FOR BIG STONE-
     TRAVERSE.

&&

$$
UPDATE...SD/DORN
SHORT TERM...SERR
LONG TERM...PARKIN
AVIATION...DORN

WEATHER.GOV/ABERDEEN