FXUS63 KBIS 042048
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
245 PM CST FRI DEC 4 2009

.SYNOPSIS...
COLD HIGH PRESSURE CENTERED OVER SASKATCHEWAN/MANITOBA AND NORTH
DAKOTA BORDERS. PATCHY LOW STRATUS WITH EAST WITH MID CLOUD
DRIFTING EAST THROUGH EASTERN MONTANA. TEMPERATURES RANGING FROM 
UPPER SINGLE DIGITS AND TEENS. 

&&

.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
WEAK LOW PRESSURE OVER EASTERN MONTANA WILL WEAKEN AS IT MOVES 
SOUTHEAST. MODELS IN FAIR AGREEMENT AND WILL USE A BLEND OF MODELS 
FOR GRIDS. WEAK LOW PRESSURE WILL WEAKEN AND MOVE SOUTHEAST AS 
ANOTHER COLD ARCTIC HIGH PRESSURE SYSTEM MOVES SOUTHEAST. MID LEVEL 
TROUGH LINGERS OVER AREA FOR ALL OF THE SHORT TERM GRIDS WITH WEAK 
VORTICITY PULSES TRIGGERING AREAS OF LIGHT SNOW IN VERY COLD 
AIRMASS. 

WITH DEEP HIGH PRESSURE OVER NORTHERN PLAINS WILL LOWER POPS NORTH
AND EAST AS MID LEVEL FLOW STEERS MOST ENERGY WEST AND EAST OF
FORECAST AREA. TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH THE
SHORT TERM.  

.LONG TERM...TUESDAY THROUGH FRIDAY
THE DOMINANT THEME OF THE LONG TERM WILL BE COLD TEMPERATURES. A 
STRONG UPPER LEVEL LOW WILL RESIDE OVER NORTHERN CANADA WITH  
TROUGHING SOUTH INTO THE CENTRAL US TUESDAY.  BOTH THE ECMWF AND GFS 
MOVE THE LOW SLOWLY WEST ALLOWING THE FLOW ACROSS THE NORTHERN US TO 
TURN ZONAL BY FRIDAY BUT 500-1000 MB THICKNESSES CONTINUE TO 
INDICATE COLD AIR OVER THE REGION.  ANY SIGNIFICANT WEATHER IS 
LIKELY TO STAY SOUTH OF THE FORECAST AREA SO...FOR THE MOST 
PART...HAVE KEPT THE POPS LOW AND HAVE NOT MENTIONED ANY 
PRECIPITATION.  MORNING TEMPERATURES LIKELY TO RANGE FROM SEVERAL 
DEGREES ABOVE ZERO TO SEVERAL DEGREES BELOW THROUGH THE PERIOD.  
DAYTIME HIGHS LIKELY TO BE 10 TO 20 DEGREES BELOW NORMAL. 

&&

.AVIATION...SUBSIDENCE ALOFT HAS HELPED CLEAR THE FORECAST AREA OF 
LOW CLOUDS.  THE TROUGH NOW IN EASTERN MONTANA WILL SWING ACROSS 
SOUTH DAKOTA AND INTO SOUTHWEST MONTANA BY NOON SATURDAY WHILE AN 
UPPER LEVEL SHORT WAVE ROTATES SOUTH INTO THE AREA FROM CANADA. COLD 
HIGH PRESSURE WILL THEN BEGIN PUSHING INTO THE STATE. CLOUD 
DEVELOPMENT LIKELY NORTH OF THE LOW AS IT TRACKS ACROSS SOUTH DAKOTA 
AND WILL BRING IN A DECK AROUND 3 THOUSAND AGL LATE IN THE FORECAST 
PERIOD MAINLY IN THE SOUTHERN TAFS OF BIS AND DIK. 

&&

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

$$

HW/TSW