FXUS63 KBIS 112159
AFDBIS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BISMARCK ND
400 PM CST FRI DEC 11 2009

.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT
MAIN FORECAST PROBLEM IN THE SHORT TERM PERIOD IS POSSIBLE HAZARD 
WITH SNOW CHANCES AND DANGEROUS WIND CHILLS. THERE ARE SOME MINOR 
DIFFERENCES BUT OVERALL GFS AND ECMWF ARE SIMILAR AND WILL UTILIZE A 
BLEND OF THE TWO.

TONIGHT...A BRIEF RETREAT OF THE ARCTIC AIR TODAY AND AND TONIGHT AS 
A WEAK SURFACE LOW MOVES ACROSS THE NORTHERN TIER ZONES. WEAK COLD 
ADVECTION BEHIND THIS SYSTEM WILL LIKELY KEEP NORTHERN ZONES COLDEST 
OVERNIGHT...BUT INCREASING CLOUDS SHOULD KEEP THEM FROM DROPPING OFF 
TOO MUCH. WILL GO WITH A RANGE OF AROUND 10 BELOW NORTH...TO AROUND 
ZERO SOUTH...WHERE DAYTIME TEMPERATURES WERE HIGHER AND COLD 
ADVECTION IS WEAKER.

THE BAROCLINIC ZONE WILL REMAIN ALONG AND JUST NORTH OF THE 
INTERNATIONAL BORDER ON SATURDAY MORNING...THEN DROP SOUTH ACROSS 
THE STATE IN THE AFTERNOON AND EVENING. THERE COULD BE SOME LIGHT 
SNOW IN THE FAR NORTH...AND THIS IS REFLECTED IN THE CURRENT 
FORECAST...BUT WILL KEEP A MENTION OF SNOW OUT OF THE SOUTH DURING 
THE DAY SATURDAY. WITH THE ARCTIC AIR SPILLING INTO THE 
REGION...EXPECT FALLING TEMPERATURES IN THE AFTERNOON...ESPECIALLY 
ACROSS THE NORTH. DEPENDING ON THE STRENGTH OF THE WINDS...MAY SEE 
WIND CHILL ADVISORY CRITERIA AS EARLY AS LATE AFTERNOON IN THE NORTH.

SATURDAY NIGHT AND SUNDAY...COLD AIR WILL CONTINUE TO SPILL INTO THE 
REGION AS ARCTIC HIGH SLIDES SOUTHEAST INTO THE AREA. BEST CHANCES 
FOR LIGHT PRECIPITATION WILL REMAIN ACROSS THE WEST...IN THE 
STRONGEST COLD ADVECTION...AND PVA IN ADVANCE OF AN APPROACHING 
SHORTWAVE. WILL LIKELY NEED TO HAVE SOME TYPE OF HIGHLIGHTS BOTH 
SATURDAY NIGHT AND SUNDAY ACROSS THE NORTH...BUT WE MAY BE ABLE TO 
HOLD OFF IN THE SOUTH. AT THIS TIME WILL HOLD OFF ON ANY HIGHLIGHTS 
BUT WILL ISSUE A SPS TO MENTION THE HAZARDOUS WEATHER POTENTIAL FOR 
THE UPCOMING WEEKEND...AND INTO NEXT WEEK.

SUNDAY NIGHT...AT THIS TIME...IT LOOKS LIKE THIS PERIOD WOULD SEE 
THE BEST CHANCE OF ACCUMULATING SNOWS ACROSS THE CWA AS THE 
AFOREMENTIONED SHORTWAVE...ORIGINATING FROM THE PACIFIC...TRAVERSES 
THE CWA. WITH THE ARCTIC AIR ENTRENCHED OVER THE AREA...WOULD EXPECT 
SOME LIGHT FLUFFY SNOW...WHICH COULD ADD UP IN SOME OCCASIONAL SNOW 
SHOWERS SUNDAY AFTERNOON THROUGH SUNDAY NIGHT. STILL TOO EARLY TO 
TELL EXACTLY WHERE THE SHORTWAVE WILL END UP GOING...BUT SOME 
PORTION OF THE CWA COULD SEE TWO TO FOUR INCHES IF CURRENT QPF 
AMOUNTS HOLD. AGAIN THIS IS A BIT TO FAR OFF TO NAIL DOWN...BUT WILL 
MENTION A POSSIBILITY OF LIGHT TO MODERATE SNOW ACCUMULATIONS IN THE 
SPS.

MONDAY THROUGH TUESDAY NIGHT...THE SNOW SHOULD TAPER OFF BY MONDAY 
MORNING. THE ARCTIC AIRMASS WILL REMAIN THROUGH MONDAY AND MONDAY 
NIGHT...WITH SOME OF THE COLDEST TEMPERATURES OF THE SEASON POSSIBLE.

.LONG TERM...TUESDAY THROUGH FRIDAY...
HEIGHTS AND THICKNESSES WILL BE ON THE INCREASE THROUGH MUCH OF THE 
EXTENDED AS THE 12Z GFS ENSEMBLES AND 12Z ECMWF ENSEMBLE MEAN ARE 
CONSISTENT WITH BUILDING HEIGHTS OVER NORTH DAKOTA AS A MEAN RIDGE 
DEVELOPS OVER THE WESTERN CONUS BY THURSDAY. THIS SHOULD LEAD THE 
WAY FROM SINGLE DIGIT HIGHS TUESDAY AFTERNOON TO THE 20S BY THURSDAY 
AFTERNOON. HPC HAS BEEN PERSISTENT WITH ADVERTISING HIGH 
TEMPERATURES IN THE LOWER 30S ACROSS SOUTHWEST NORTH DAKOTA 
THURSDAY. THE 30S MAY BE TOO OPTIMISTIC AS THE RIDGE AXIS REMAINS 
WEST OF NORTH DAKOTA...HOWEVER WILL NOT DEVIATE MUCH FROM PREVIOUS 
GRIDS WHICH ALREADY HAD SOME SEMBLANCE OF 30S ACROSS THE SOUTHWEST. 
THE OPERATIONAL GFS/ECMWF DO SHOW SLIGHTLY COLDER AIR MOVING IN FOR 
FRIDAY...AS THE WESTERN RIDGE AMPLIFIES AND A CORRESPONDING STRONGER 
NORTHWEST FLOW DEVELOPS OVER NORTH DAKOTA. IN DOING SO BOTH MODELS 
SWING AN ALBERTA CLIPPER TYPE SYSTEM THROUGH THURSDAY NIGHT/FRIDAY 
TIMEFRAME. THE 12Z ECMWF IS MORE ROBUST WITH PRECIPITATION CHANCES 
THAN THE GFS. BEING THIS FAR OUT WILL CONTINUE TO FOLLOW PREVIOUS 
DRY FORECAST AND CURRENT DRY HPC OUTLOOK UNTIL WE GET CLOSER OR SEE 
BETTER CONSISTENCY. OVERALL SENSIBLE WEATHER GRID ELEMENTS AT LEAST 
THROUGH THURSDAY ARE DRY WITH A MODERATING TREND.

&&

.AVIATION...A WEAK ALBERTA CLIPPER WILL BRING A WINDSHIFT FROM 
SOUTHWEST TO NORTHWEST THIS EVENING ACROSS CENTRAL NORTH DAKOTA. VFR 
CONDITIONS WILL CONTINUE THROUGH 06Z. BY 12Z SATURDAY...AN ARCTIC 
FRONT WILL TAKE SHAPE AND MOVE INTO SOUTHERN ALBERTA AND SOUTHERN 
SASKATCHEWAN. THIS ARCTIC FRONT AND ASSOCIATED FRIGID AIR WILL 
SLOWLY OOZE FROM NORTH TO SOUTH BEGINNING SATURDAY NIGHT...BUT NOT 
COMPLETE ITS JOURNEY THROUGH NORTH DAKOTA UNTIL MONDAY NIGHT. SOME 
AREAS OF VERY LIGHT SNOW WILL DEVELOP SATURDAY MORNING OVER THE 
NORTHWESTERN AND NORTHERN TAF SITES AROUND KISN/KMOT WITH MVFR 
CEILINGS. EXPECT VFR CEILINGS TO CONTINUE ELSEWHERE THROUGH 18Z 
SATURDAY.

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

$$
TWH/KS