FXUS63 KBIS 040932
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
330 AM CST FRI DEC 4 2009

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT...
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE CONTINUED BELOW 
SEASONAL TEMPERATURES THROUGH THE WEEKEND. WILL UTILIZE AN OVERALL 
MODEL BLEND.

CURRENTLY...POSITIVELY TILTED UPPER LEVEL TROUGH IN PLACE ACROSS THE 
CENTRAL CONUS...EXTENDING SOUTHWEST FROM A CLOSED UPPER LOW JUST 
SOUTH OF THE HUDSON BAY REGION. NORTHERLY FLOW ALOFT ACROSS THE 
NORTHERN PLAINS...WITH AN EMBEDDED IMPULSE SLIDING FROM SOUTH 
CENTRAL CANADA INTO WESTERN ND. THIS IMPULSE IS RESULTING IN SOME 
LOW STRATUS WITH LIKELY FLURRIES OVER MY FAR NORTH CENTRAL 
ATTM...WITH THIS AREA OF LOW CIGS ADVECTING SOUTH-SOUTHEAST WITH THE 
WAVE. NORTHWESTERLY LOW LEVEL FLOW COMBINED WITH SFC TEMPERATURES IN 
THE SINGLE DIGITS TO LOW TEENS IS ONCE AGAIN GENERATING LAKE AFFECT 
SNOW OFF OF LAKE SAKAKAWEA STRETCHING SOUTHEAST INTO THE BISMARCK 
AREA. 

WILL MAINTAIN SCATTERED FLURRIES THROUGH THE MORNING HOURS CENTRAL 
AND EAST TO ACCOUNT FOR THE EMBEDDED S/WV SWINGING SOUTH-SOUTHEAST 
ACROSS THE LOCAL AREA. LAKE AFFECT SNOW SHOWERS WILL END OVER THE 
NEXT FEW HOURS AS 1) UPPER LEVEL SUPPORT PUSHES SOUTH AND 2) LOW 
LEVEL WINDS SHIFT FROM NORTHWEST TO MORE WEST BETWEEN NOW AND 
12Z...THEN MORE SOUTHWESTERLY AFTER 18Z TODAY. LOW LEVEL MOISTURE 
PROFILES AND LACK OF MID/UPPER LEVEL DISTURBANCES SHOULD RESULT IN 
CLEARING SKIES FOR MOST AREAS THIS AFTERNOON. EXPECTING A WIDE RANGE 
OF TEMPERATURES ACROSS THE FORECAST AREA DESPITE THIS CLEARING AND 
WAA...WITH DAYTIME HIGHS DEPENDENT ON SNOW COVER AND ANY LINGERING 
CLOUD COVER. FORECAST HIGHS CURRENTLY RANGE FROM THE MID 20S 
SOUTHWEST TO THE LOW/MID TEENS NORTH CENTRAL AND NEAR THE DEVILS 
LAKE BASIN AREA. HIGHS NEAR 30F CANNOT BE RULED OUT ACROSS THE 
SOUTHWEST WHERE THE GROUND REMAINS BARE. 

SATURDAY WILL FEEL THE EFFECTS OF COOL CYCLONIC FLOW ALOFT AS AN 
UPPER LEVEL IMPULSE ROTATING AROUND THE HUDSON BAY LOW SWINGS 
SOUTH-SOUTHWEST INTO THE NORTHERN PLAINS AND LINKS UP ANOTHER SHORT 
WAVE TROUGH SWINGING THROUGH MONTANA. BEST CHANCES FOR SNOW AND 
HENCE THE BEST CHANCES FOR LIGHT ACCUMULATIONS LOOK TO BE ACROSS MY 
SOUTHWESTERN COUNTIES WHERE THE UPPER LEVEL SUPPORT COINCIDES WITH 
THE LOW LEVEL FORCING OF A WEAK SFC TROUGH. CAA SATURDAY NIGHT INTO 
SUNDAY NIGHT WILL RESULT IN LOWS NEAR TO BELOW ZERO AND HIGHS FROM 
THE SINGLE DIGITS ABOVE TO LOW/MID TEENS FOR SUNDAY. WILL STAY THE 
COURSE WITH SLIGHT CHANCES FOR SNOW DURING THIS TIMEFRAME AS WELL AS 
MORE OFTEN THAN NOT WE SEE LOW CIGS AND SCATTERED LIGHT SNOW SHOWERS 
WITH THIS SORT OF CAA PATTERN DURING THE WINTER. 
             

.LONG TERM...MONDAY THROUGH THURSDAY
MODELS ARE IN SLIGHTLY BETTER AGREEMENT TODAY FOR THE EXTENDED 
PERIOD. THE POLAR VORTEX WILL HAVE BEGUN ITS MIGRATION FROM THE 
ARCTIC OCEAN  INTO CANADA BY MONDAY...AS THE LOW THAT HAD BEEN 
ANCHORED OVER THE HUDSON BAY AREA OPENS AND MOVES AWAY. WITH THE 
LOSS OF THE HUDSON LOW INFLUENCE ON THE MAIN BELT OF 
WESTERLIES...AND THE DEVELOPMENT OF A CLOSED LOW OVER THE PACIFIC 
NORTHWEST...AN AREA OF WEAK UPPER LEVEL FLOW IS EXPECTED TO SET UP 
OVER THE NORTHERN PLAINS AT THE BEGINNING OF NEXT WEEK. BY 
TUESDAY...AS THE POLAR VORTEX MOVES FARTHER SOUTH...IT PICKS UP THE 
NORTHWEST LOW AND MOVES IT ACROSS THE NORTHERN HALF OF THE CONUS 
THROUGH WEDNESDAY. RIGHT NOW...THE SYSTEM LOOKS TO REMAIN MAINLY TO 
OUR SOUTH...BUT HAVE ADDED SMALL POPS TO FAR SOUTH AND WILL WATCH 
FURTHER MODEL RUNS TO SEE HOW THE SYSTEM MAY EVOLVE.  ONCE THIS 
SYSTEM MOVES OUT OF THE PLAINS...CYCLONIC NORTHWEST TO WESTERLY FLOW 
ALOFT SHOULD THEN REMAIN OVER THE CWA FOR THE REMAINDER OF THE 
EXTENDED...AS THE SOUTHERN PERIPHERY OF THE POLAR VORTEX BEGINS TO 
INFLUENCE NORTH DAKOTA. 

WILL KEEP TEMPERATURES BELOW NORMAL THROUGH THE TERM...AND HAVE 
AGAIN TRENDED MOST PERIODS DOWN SLIGHTLY. THERE ARE HINTS AT AN 
EXTREMELY COLD AIRMASS BRUSHING NORTH DAKOTA WED/WED NITE AND 
ADDITIONAL DOWNWARD ADJUSTMENTS MAY BE NEEDED.

&&

.AVIATION...
MOST CLOUDS HAVE LEFT THE AREA OVERNIGHT...RESULTING IN VFR 
CONDITIONS FOR MOST TAF SITES. THE EXCEPTION IS KBIS...WHERE CIGS 
BELOW 2000 FT AGL AND FLURRIES ARE RESULTING FROM ENHANCED MOISTURE 
OFF LAKE SAKAKAWEA. WILL ALSO MONITOR POTENTIAL FOR SOME LOWER CIGS 
TO IMPACT KMOT  BREEZY NORTHWEST WINDS SHOULD BECOME LIGHT AND 
MORE SOUTHERLY BY THIS EVENING...WITH CLEAR SKIES GIVING WAY TO SOME 
HIGH AND MID LEVEL CLOUDS TONIGHT. VFR CONDITIONS SHOULD PREVAIL 
UNTIL LATE SATURDAY. 

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SHORT TERM...NH
LONG TERM/AVIATION...BPN