FXUS63 KBIS 060304
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
904 PM CST SAT DEC 5 2009

.UPDATE...
00Z NAM MOSTLY IN NOW AND NO SURPRISES THIS EVENING. UPPER TROUGH
ALONG A LINE FROM TROTTERS EAST TO GARRISON AND INTO HARVEY AS OF
02Z. THIS SHORTWAVE TROUGH ALOFT WILL CONTINUE TO PRESS SOUTH PER
LATEST WATER VAPOR IMAGERY AND NAM FORECAST. REGIONAL RADAR SHOWING
SOME WEAK PRECIPITATION RETURNS OVER THE SOUTHERN ONE THIRD OF OUR
CWA. THIS IS IN RESPONSE TO THE UPPER SHORTWAVE AND A WEAK AREA OF
850-50OMB FRONTOGENESIS. NOTHING MORE THAN TRACE AMOUNTS THUS FAR
TODAY INTO THIS EVENING. THE NAM CONTINUES TO PUSH THIS AREA OF
LIGHT SNOW/FLURRIES SOUTH OVERNIGHT WITH LOW LEVEL COLD AIR ADVECTION
TAKING CONTROL FROM NORTHWEST TO SOUTHEAST ONCE AGAIN THROUGH SUNDAY.
LATEST FOG/STRATUS LOOP SHOWS SOME POCKETS OF CLEAR SKIES AND
OTHER AREAS OF STRATUS. THE NAM 925MB RH FIELD/MOISTURE AND
TEMPERATURE FIELD SUGGEST WITH LOW LEVEL COLD AIR ADVECTION
CONTINUING WITHIN THE NEARLY SATURATED LAYER TONIGHT/SUNDAY...MORE
AREAS OF LOW CLOUDS AND OCCASIONAL FLURRIES WILL ENSUE. THIS IS
COVERED WELL IN THE GRIDS. LOW TEMPERATURES WILL BE DIFFICULT
DEPENDING ON THE AMOUNT AND DURATION OF CLEARING EARLY TONIGHT. 
HOWEVER...PREVIOUS FORECAST HOURLY TEMPS COMPARING FAIRLY WELL
WITH OBSERVED TEMPS...AND THUS AT THIS TIME WILL NOT UPDATE THE
FORECAST UNLESS TEMPS BEGIN TO DEVIATE SIGNIFICANTLY FROM CURRENT
TREND. OVERALL FORECAST IS ON TRACK. SEE PREVIOUS DISCUSSION BELOW
FOR FURTHER DETAILS.

KS

&&

.PREV DISCUSSION... /ISSUED 310 PM CST SAT DEC 5 2009/ 

SYNOPSIS...
COLD HIGH PRESSURE BUILDING SOUTH ALONG FRONT RANGE OF THE
CANADIAN ROCKIES WILL BRING BELOW AVERAGE TEMPERATURES TO THE
NORTHERN PLAINS FOR THE FORESEEABLE FUTURE. MOIST BOUNDARY LAYER
WITH SMALL RIPPLES OF ENERGY WILL TRIGGER SCATTERED AREAS OF LIGHT
SNOW OR OCCASIONAL FLURRIES. 

SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
WILL USE COMBO OF GRIDS FOR TODAYS PACKAGE INCLUDING GFS/ECMWF AND
SREF. 

ARCTIC HIGH PRESSURE IS THE STORY OF THE REMAINDER OF THIS WEEKEND
AND INTO EARLY NEXT WEEK. BROAD TROUGHING OVER MUCH OF THE CENTRAL
CONUS WILL SHUNT STRONGER SYSTEMS WEST...SOUTH AND EAST OF
FORECAST AREA WITH RESULTING PRECIPITATION FIELDS FROM THESE
SYSTEMS SKIRTING THE SOUTHERN BOUNDARIES OF NORTH DAKOTA. 

MID LEVEL LOW MOVING SOUTH ALONG SPINE OF THE ROCKIES WILL CREATE
LEE TROUGHING OVER COLORADO WITH LOW MOVING EAST ONTO CENTRAL
PLAINS ON MONDAY CAUSING SIGNIFICANT WINTER EVENT OVER NEBRASKA TO
SOUTH OF GREAT LAKES. SOME FLURRIES OR LIGHT SNOW WILL CONTINUE AS
COLD 1040 MB HIGH PRESSURE CONTINUES TO BUILD SOUTH OVER NORTHERN
PLAINS. 

NEXT SYSTEMS IS SLIGHTLY FARTHER NORTH ON SREF WITH QPF FIELD JUST
BRUSHING SOUTHERN COUNTIES. WILL NOT AT MEASURABLE PRECIPITATION
FOR NOW. TEMPERATURES WILL BE COLD BUT NOWHERE CLOSE TO RECORDS. 

LONG TERM...WEDNESDAY THROUGH SATURDAY
THE MODELS CONTINUE TO BE IN FAIR AGREEMENT ON THE LARGE SCALE TREND 
OVER THE LONG TERM. WEDNESDAY WILL SEE A LARGE UPPER LEVEL 
TROUGH WHICH WILL EXTEND FROM AN UPPER LEVEL LOW OVER NORTHERN 
CANADA SOUTH INTO THE CENTRAL PLAINS.  THE TROUGH WILL BREAK DOWN 
OVER TIME AS THE ANCHORING UPPER LEVEL LOW SWINGS DOWN INTO SOUTHERN 
CANADA CREATING A BROAD AREA OF ZONAL FLOW ACROSS THE US BUT KEEPING 
THE FORECAST AREA UNDER A VERY COLD AIRMASS. ANY SIGNIFICANT WEATHER 
WILL BE SHUNTED SOUTH OF THE FORECAST AREA.  

AVIATION...AVIATION CONTINUES TO BE A CHALLENGE.  CLEARING HAS BEEN 
OCCURRING OVER NORTHERN NORTH DAKOTA AND SOUTHERN MANITOBA AND 
SASKATCHEWAN BUT FURTHER NORTH THERE CONTINUES TO BE AREAS OF LOW 
CLOUDS.  EXPECT CONDITIONS TO IMPROVE ACROSS THE SOUTHERN NORTH 
DAKOTA EARLY TONIGHT...BUT LIKELY TO SEE MORE LOW CLOUDS MOVE INTO 
THE STATE LATER TONIGHT AS HIGH PRESSURE BUILDS INTO THE AREA. 

&&

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

$$

HW/TWS