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000
FXUS63 KBIS 031125
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
525 AM CST TUE DEC 3 2013

.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 500 AM CST TUE DEC 3 2013

THE SHORT TERM PERIOD HAS BEEN ADJUSTED TO RUN THROUGH WEDNESDAY
NIGHT AND DEAL WITH THE ENTIRE STORM THROUGH ITS FINISH. OTHER
SHORT TERM RESPONSIBILITIES WERE TAKEN UP BY THE LONG TERM
FORECASTER.

WARNING CONTINUES FOR THE SOUTHERN TWO THIRDS OF THE FORECAST
AREA. ACROSS THE NORTHERN THIRD THE WARNING HAS BEEN REPLACED BY
AN ADVISORY AS LESS SEVERE WINTER WEATHER AND IMPACTS ARE NOW
EXPECTED THERE.

THE INCREASING NORTHEAST WIND INTO THE NORTHEAST PART OF THE
FORECAST AREA...WITH DEW POINTS DOWN TO 10...HAS RAISED CONCERN
THAT TOO MUCH DRY AIR WAS WORKING IN TO THE NORTHERN PART OF THE
STORM...AND WILL PREVENT SIGNIFICANT SNOW ACCUMULATION THERE.
THIS CONCERN IS FOR TWO COUNTIES DEEP INTO THE STATE FROM THE
CANADIAN LINE. THIS AREA WILL STILL SEE BLOWING AND DRIFTING
SNOW...JUST NOT SIGNIFICANT ADDITIONAL SNOW AMOUNTS. HAVE
ATTEMPTED TO USE STRONG WORDS IN THE ADVISORY. THE BEST CHANCE OF
ACCUMULATING SNOW IN THE ADVISORY AREA WILL BE TUESDAY NIGHT AS
THE LOW CENTER PASSES CLOSEST...WITH THE NORTHERN EDGE OF THE WARM
CONVEYOR BELT OVERRUNNING THE COLD AIR. ADDING TO THIS THINKING
THAT THE NORTH WILL BE SPARED THE HEAVY SNOW WAS THE 4 MB
PRESSURE RISES PER 3 HOURS EARLIER ACROSS NORTHERN MONTANA INTO
THE WILLISTON AREA.

THE GFS MODEL HAS VERIFIED BEST SO FAR WITH THIS SYSTEM...AT LEAST
WHEN COMPARING MODEL RUNS FROM 24 HOURS AGO. THE GFS HAD THE BAND
OF SNOW GOING ACROSS SOUTH DAKOTA PEGGED...AND SHOWED THE SOUTHERN
PART OF THE FORECAST AREA GETTING THE BRUNT OF THE STORM...AS
COMPARED TO THE NORTH.

FOLLOWING THE GFS WOULD BRING SNOW ACROSS THE FORECAST AREA AS THE
DAY PROGRESSES...HEAVIEST SOUTH...AND CONTINUE THROUGH THE FIRST
HALF OF TUESDAY NIGHT BEFORE DECREASING IN THE WEST. LIGHT SNOW /
FLURRIES CONTINUE THROUGH WEDNESDAY.

OTHER IMPACTS WILL BE THE 30 MPH GUSTS THAT CAUSE BLOWING AND
DRIFTING SNOW AND REDUCED VISIBILITY. FOLLOWING THAT THE ATTENTION
TURNS TO SIGNIFICANTLY BELOW NORMAL TEMPERATURES...AND DANGEROUSLY
LOW WIND CHILLS.

.LONG TERM...(THURSDAY THROUGH MONDAY)
ISSUED AT 500 AM CST TUE DEC 3 2013

THE MAIN FORECAST CONCERNS IN THE EXTENDED PERIOD ARE FRIGID
TEMPERATURES AND RESULTING HIGHLIGHTS. WILL UTILIZE A MODEL BLEND
WITH PERSISTENCE FOR WEATHER ELEMENTS.

BY THE TIME WE REACH THE EXTENDED PERIOD (THURSDAY) ARCTIC AIR HAS
SETTLED ACROSS THE NORTHERN PLAINS AND SOUTHERN PRAIRIE PROVINCES OF
CANADA. WITH BROAD UPPER LEVEL TROUGH ACROSS MOST OF THE WESTERN AND
CENTRAL U.S. THERE MAY BE A LITTLE LINGERING LIGHT SNOW ACROSS THE
NORTH AND EAST PORTION OF THE CWA...AS THE UPPER LEVEL LOW REMAINS
SITUATED OVER THE AREA...BUT ARCTIC SURFACE HIGH PRESSURE WILL BE
THE DOMINANT FACTOR AND NO SIGNIFICANT ACCUMULATIONS ARE EXPECTED
THURSDAY.

FRIDAY AND SATURDAY WILL BE DRY BUT WILL REMAIN BITTERLY COLD AS THE
ARCTIC SURFACE HIGH MOVES SLOWLY EAST ACROSS THE REGION. THE COLDEST
OF THE AIR MASS MOVES EAST OF THE AREA SATURDAY NIGHT AND
TEMPERATURES WARM SLIGHTLY SUNDAY BEFORE A REINFORCING SHOT OF
ARCTIC AIR ARRIVES SUNDAY NIGHT. WE COULD SEE A CHANCE OF LIGHT SNOW
SATURDAY NIGHT INTO SUNDAY AS A SHORTWAVE MOVES THROUGH THE LARGE
UPPER LEVEL TROUGH...BUT AT THIS TIME IT APPEARS THAT WAVE AND
RESULTING PRECIPITATION WILL REMAIN MAINLY TO OUR SOUTH.

TEMPERATURES THROUGH THE EXTENDED PERIOD WILL REMAIN WELL BELOW
NORMAL WITH HIGHS MAINLY IN THE SINGLE DIGITS BELOW ZERO...THE FAR
SOUTH MAY BE THE ONLY AREA TO SEE ABOVE ZERO TEMPERATURES THURSDAY
THROUGH SATURDAY. TEMPERATURES MODIFY SLIGHTLY ON SUNDAY AHEAD OF
THE NEXT ARCTIC SURGE...BUT HIGHS ACROSS THE NORTH MAY STILL REMAIN
BELOW ZERO. IN GENERAL LOWS WILL RANGE FROM 10 TO 20 BELOW. SNOWFALL
IN THE SHORT TERM PERIOD WILL HAVE A NEGATIVE INFLUENCE ON
TEMPERATURES. A BLANKET OF FRESH SNOW COULD RESULT IN EVEN COLDER
TEMPERATURES THAN CURRENTLY FORECAST.

WE WILL DEFINITELY NEED WIND CHILL HIGHLIGHTS...PERHAPS THROUGH THE
ENTIRE EXTENDED PERIOD FOR SOME AREAS. HOWEVER AT THIS TIME WITH THE
CURRENT SHORT TERM HEADLINES IN EFFECT...WILL HIGHLIGHT THE
DANGEROUS WIND CHILLS IN THE HAZARDOUS WEATHER OUTLOOK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 500 AM CST TUE DEC 3 2013

HAZARD TO AVIATION WILL FOCUS ON WINTER STORM SPREADING ANOTHER
ROUND OF SNOW INTO NORTH DAKOTA TODAY AND TONIGHT. IFR TO MVFR
CONDITIONS ACROSS THE AREA AT 10Z IN LOW STRATUS. LIGHT TO MODERATE
SNOW MOVING INTO WESTERN NORTH DAKOTA WILL SPREAD EAST INTO CENTRAL
NORTH DAKOTA THROUGH 18-21Z. IFR CONDITIONS EXPECTED ACROSS SOUTHERN
TAF SITES OF KDIK-KBIS-KJMS FROM 21Z-12Z IN SNOW AND BLOWING SNOW.
KISN-KMOT WILL SEE MVFR TO IFR CONDITIONS WITH LIGHT SNOW AND
BLOWING SNOW THROUGH THE ENTIRE PERIOD.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 6 PM CST /5 PM MST/ WEDNESDAY FOR
NDZ018>023-025-031>037-040>048-050-051.

WINTER WEATHER ADVISORY UNTIL 6 PM CST WEDNESDAY FOR NDZ001>005-
009>013-017.

&&

$$

SHORT TERM...JPM
LONG TERM...TWH
AVIATION...TWH