FXUS65 KMSO 011136
AFDMSO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
436 AM MST TUE DEC 1 2009

.UPDATE...CANCELED THE WINTER WEATHER ADVISORY

&&

.DISCUSSION...WIDESPREAD SIGNIFICANT ACCUMULATING SNOWS IN THE
GLACIER NP REGION HAVE DIMINISHED TO SNOW SHOWERS. LIGHT
ACCUMULATIONS WITHIN STRONGER SHOWERS ARE POSSIBLE THROUGH 9 AM.

&&

.AVIATION...MORNING RAIN AND SNOW SHOWERS ARE EXPECTED AT
KGPI...KMSO AND KBTM. EXPECT MOUNTAIN OBSCURATIONS AND REDUCED
VISIBILITIES AT TIMES. KGPI MAY EXPERIENCE SOME GUSTY WINDS AFTER
13Z AS THE INITIAL PUSH OF MUCH COLDER AIR ENTERS THE REGION. 

&&

.PREV DISCUSSION... /ISSUED 418 AM MST TUE DEC 1 2009/ 

DISCUSSION...A COLD FRONT IS CURRENTLY MOVING THROUGH THE
NORTHERN ROCKIES THIS MORNING. A WELL DEFINED BOUNDARY OF RAIN AND
SNOW ALONG THE FRONTAL PASSAGE IS SEEN ON RADAR IN WEST CENTRAL
MONTANA WITH SHOWERY CONDITIONS BEHIND THE FRONT IN NORTHWEST
MONTANA. THE FRONT AND ASSOCIATED RAIN AND SNOW WILL SLOWLY MOVE
SOUTHEASTWARD INTO SOUTHWEST MONTANA LATER THIS MORNING THEN EXIT
THE REGION DURING THE EARLY AFTERNOON HOURS. SURFACE HIGH PRESSURE
WILL MOVE SOUTH FROM BRITISH COLUMBIA INTO THE NORTHERN ROCKIES
LATER TODAY AND OVERNIGHT AND PRODUCE MUCH COLDER TEMPERATURES AND
DRY CONDITIONS. EXPECT NORTH WINDS TO INCREASE IN NORTHWEST
MONTANA TODAY AS THE INITIAL PUSH OF COLD AIR ENTERS THE REGION.

WEDNESDAY AND THURSDAY...AN INACTIVE WEATHER PATTERN WILL
ENCOMPASS THE NORTHERN ROCKIES UNDER HIGH PRESSURE ALOFT ALONG
THE WEST COAST ... WITH A SURFACE HIGH OVER THE NORTHERN
ROCKIES. THIS PATTERN WILL PRODUCE MAINLY CLEAR SKIES AND DRY
CONDITIONS. MODEL SOUNDINGS ARE INDICATING SOME WEAK AND SHALLOW
INVERSIONS WEDNESDAY AND THURSDAY MORNING. THE RECENT
PRECIPITATION WITH THESE WEAK INVERSIONS MAY BE ENOUGH TO PRODUCE
SOME PATCHY MORNING VALLEY FOG.

FRIDAY THROUGH MONDAY...EVEN THOUGH THE MODELS DISAGREE ON
FEATURES FOR THE END OF THE WEEK...THEY COME IN FAIRLY GOOD
AGREEMENT FOR THE WEEKEND AND EARLY NEXT WEEK. BOTH THE ECMWF AND GFS
SHOW A BROAD TROUGH DEVELOPING OVER THE REGION. A FAIRLY STRONG
SURFACE HIGH WILL DROP PRACTICALLY DUE SOUTH OUT OF ALBERTA. THIS
HIGH PRESSURE WILL BE ACCOMPANIED BY A DEEP ARCTIC AIR MASS
PUSHING INTO THE AREA. TEMPERATURES FOR THE WEEKEND ARE CURRENTLY
FORECAST TO BE AROUND 10 DEGREES BELOW SEASONAL NORMALS...BUT HAVE
THE POTENTIAL TO BE EVEN COOLER AROUND 20 DEGREES BELOW NORMAL.
ALSO THIS BROAD TROUGH WILL BE FAIRLY UNSTABLE WITH PRIMARILY
OROGRAPHIC SHOWERS...ESPECIALLY ALONG THE CONTINENTAL DIVIDE. 

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&

$$

SHORT TERM...RPN
LONG TERM....RPN
AVIATION...RPN