108
FXUS65 KMSO 192027
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
127 PM MST THU DEC 19 2024
DISCUSSION
KEY MESSAGES:
- SLIGHT CHANCE FOR FREEZING RAIN IN NORTHWEST MONTANA VALLEYS
TONIGHT
- VALLEY MIXED PRECIPITATION AND MOUNTAIN PASS LEVEL SNOW EXPECTED
SATURDAY NIGHT AND SUNDAY
AFTERNOON SATELLITE IMAGERY SHOWS CLOUD COVER STREAMING INTO THE
REGION FROM THE WEST AHEAD OF A SHORTWAVE TROUGH EXPECTED TO PASS
TONIGHT. THIS SYSTEM WILL BRING LIGHT PRECIPITATION TO FAR
NORTHWEST MONTANA, PRIMARILY IN NORTHERN LINCOLN AND FLATHEAD
COUNTIES. MOUNTAIN SNOW AND A VALLEY WINTRY MIX ARE POSSIBLE, WITH
KALISPELL HAVING A 20% CHANCE OF PRECIPITATION. IF IT OCCURS,
LIGHT FREEZING RAIN IS THE MOST LIKELY OUTCOME.
A "DIRTY" RIDGE OF HIGH PRESSURE WILL DOMINATE THROUGH SATURDAY,
ALLOWING WEAK DISTURBANCES TO BRING INTERMITTENT CLOUD COVER.
A MORE SIGNIFICANT TROUGH OF LOW PRESSURE REMAINS ON TRACK TO
MOVE THROUGH NORTH-CENTRAL IDAHO AND WESTERN MONTANA SATURDAY
NIGHT INTO SUNDAY. PRE-FRONTAL WARMING WILL RAISE SNOW LEVELS,
LEADING TO A WINTRY MIX IN THE VALLEYS AND THE POTENTIAL FOR
FREEZING RAIN, DEPENDING ON THE THERMAL PROFILE. THE GFS MODEL
SHOWS A FASTER COLD FRONT WITH VALLEY SNOW SUNDAY MORNING, WHILE
THE ECMWF MODEL SUGGESTS SLOWER TIMING AND HIGHER SNOW LEVELS. THE
TIMING OF THE COLD FRONT WILL DETERMINE THE EXTENT OF FREEZING
RAIN.
NEXT WEEK, ENSEMBLE GUIDANCE INDICATES AN ACTIVE WEATHER PATTERN
WITH FLUCTUATING SNOW LEVELS. EXPECT CONTINUED WINTRY MIX IN
VALLEYS AND ACCUMULATING SNOW AT MOUNTAIN PASSES AND HIGHER
ELEVATIONS.
AVIATION
HIGH CLOUDS ARE STREAMING INTO THE REGION FROM THE
WEST AHEAD OF AN APPROACHING SHORTWAVE TROUGH. AS THE TROUGH
NEARS, CLOUD COVER IS EXPECTED TO LOWER, OBSCURING TERRAIN BY
TONIGHT. PRECIPITATION WILL LIKELY REMAIN CONFINED TO NORTHWEST
MONTANA, WITH A SLIGHT CHANCE OF FREEZING RAIN AT KGPI OVERNIGHT.
STABLE VALLEY CONDITIONS COMBINED WITH STRENGTHENING WINDS ALOFT
WILL HEIGHTEN THE RISK OF LOW-LEVEL WIND SHEAR, PARTICULARLY AT
KBTM OVERNIGHT.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page