FXUS65 KMSO 091039
AFDMSO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
339 AM MST WED DEC 9 2009

.DISCUSSION...NORTHWESTERLY FLOW WILL PERSIST OVER THE NORTHERN
ROCKIES TODAY THROUGH THURSDAY. THIS FLOW PATTERN WILL ALLOW FOR A
FEW WEAK DISTURBANCES TO PASS THROUGH THE REGION CAUSING A FEW
LIGHT SNOW SHOWERS ESPECIALLY IN THE HIGHER TERRAIN. ALSO
TEMPERATURES WILL GRADUALLY MODERATE THE NEXT COUPLE OF DAYS.
TODAYS MAXIMUM TEMPERATURES WILL CONTINUE TO BE AROUND 20 DEGREES
BELOW NORMAL AND BY FRIDAY TEMPERATURES APPEAR TO BECOME 10
DEGREES BELOW AVERAGE. THE PATTERN BEGINS TO CHANGE ON FRIDAY AS A
LOW PRESSURE APPROACHES THE OREGON COAST FROM THE WEST PLUS
ANOTHER ARCTIC PUSHING INTO ALBERTA AND SASKATCHEWAN. AT THE
MOMENT IT APPEARS THAT THE GLACIER PARK COULD SEE UPSLOPE
PRECIPITATION WHILE A MOISTURE FETCH MOVES INTO NORTH CENTRAL
IDAHO. THE TIMING OF PRECIPITATION ON FRIDAY IS STILL A LITTLE
UNCERTAIN.

SATURDAY THROUGH WEDNESDAY... THE EVOLUTION OF THIS WEEKENDS
SYSTEM BY MODEL GUIDANCE HAS BEEN INTERESTING THE LAST FEW
DAYS. ON TUESDAY NIGHT A COMPROMISE BETWEEN THE GFS AND ECMWF WAS
PREFERRED...THEN DURING THE DAY THE 08/12Z GFS WAS
DISREGARDED...AND NOW A SLOWER AND WEAKER VERSION OF THE 09/00Z
ECMWF IS THE SOLUTION OF CHOICE. SINCE THE ECMWF HAS HAD
PREFERENCE THE LAST FEW RUNS...THE EXTENDED FORECAST HAS BEEN
NUDGED TOWARDS ITS DEPICTION. WHAT THIS ALL MEANS...IS THAT THE
PACIFIC LOW PRESSURE SYSTEM WILL PASS FAR ENOUGH TO THE SOUTH THAT
MOST OF THE NORTHERN ROCKIES WILL NOT SEE A STRONG INFLUENCE FROM
THE INCREASED MOISTURE. THE CANADIAN LOW PRESSURE SYSTEM IS ALSO
WEAKER WITH MUCH UNCERTAINTY AS TO WHETHER WESTERN MONTANA WILL SEE
THE COOLER ARCTIC AIR OR NOT. THESE TWO SYSTEMS STILL HAVE THE
POTENTIAL TO PRODUCE A DECENT CHANCE FOR SNOW...BUT WITH MOST OF THE
MOISTURE AND ENERGY BEING TO THE SOUTH... SIGNIFICANT SNOW
ACCUMULATIONS LOOK TO BE UNLIKELY AT THIS TIME.

&&

.AVIATION...THE FLOW PATTERN IS BECOMING NORTHWESTERLY TODAY
ALLOWING FOR MOISTURE AND WEAK DISTURBANCES TO MOVE THROUGH THE
NORTHERN ROCKIES. THE CEILING HEIGHTS WILL BE FAIRLY LOW FOR AT
LEAST THE NEXT 24 HOURS CAUSING MOUNTAINS AND PASSES TO BE
OBSCURED AT TIMES. ALSO THE REGION COULD SEE LIGHT SNOW WHICH
COULD REDUCE VISIBILITIES TO MVFR.

&&

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

$$

SHORT TERM...SMITH
LONG TERM....KITSMILLER
AVIATION...SMITH