633
FXUS65 KGGW 182119
AFDGGW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
219 PM MST WED DEC 18 2024
DISCUSSION
KEY MESSAGES:
- HEADLINES:
WINTER WEATHER ADVISORY: THRU 5 AM THU
HIGH WIND WARNING: THRU 11 AM THU
COLD WEATHER ADVISORY: 12 AM - 12 PM THU
- LIGHT SNOW AND ICE ACCUMULATIONS, HIGH WINDS, BLOWING SNOW AND
DANGEROUS WIND CHILLS WILL MAKE FOR DIFFICULT TRAVEL TONIGHT
- WARMING TO ABOVE AVERAGE TEMPERATURES BY CHRISTMAS DAY
WEATHER PATTERN OVERVIEW:
WRAP AROUND MOISTURE FROM THE SYSTEM LINGERS TONIGHT,
TRANSITIONING FROM A WINTRY MIX TO MOSTLY SNOW AS IT EXITS THE
FAR NE CORNER OF MONTANA. WHILE THE PRIMARY IMPACT TO MOST AREAS
IS A LIGHT GLAZE OF ICE ACCUMULATION, AREAS AROUND PLENTYWOOD HAVE
THE GREATEST CHANCE FOR APPROACHING 3 INCHES ACCUMULATION FROM
LINGERING SNOWFALL BY THURSDAY MORNING. THE PASSAGE OF THIS SYSTEM
WITH COLD AIR ADVECTION TONIGHT WILL ALSO BRING WIDESPREAD WIND
GUSTS OUT OF THE NORTHWEST IN EXCESS OF 50 MPH. WIND CHILLS ALSO
BECOME A CONCERN WITH AN OVERLAP OF SUBZERO TEMPERATURES AND STILL
ELEVATED WINDS THURSDAY MORNING NEAR THE CANADIAN BORDER, WITH
VALUES IN THE -20S TO AROUND -30 FOR SEVERAL HOURS.
BY FRIDAY, WE RETURN TO NORTHWESTERLY FLOW ALOFT. A SHORTWAVE
LOOKS TO REMAIN FAR ENOUGH AWAY IN MANITOBA TO BRING LITTLE OR NO
PRECIPITATION FOR FRIDAY. THIS WILL ALSO ALLOW A PROLONGED WARM UP
INTO CHRISTMAS DAY AS LOW-LEVEL WINDS PROVIDE A CHINOOK EFFECT.
FORECAST CONFIDENCE & DEVIATIONS:
WINDS WERE WEIGHTED HEAVILY TOWARD THE NBM 90TH PERCENTILE THROUGH
THURSDAY. CONFIDENCE IS HIGH ON THE GENERAL PATTERN LEADING TO
MOSTLY DRY AND MILD CONDITIONS BY EARLY NEXT WEEK, WHILE STILL
MODERATE FOR PRECIPITATION TYPE AND EXTENT OF HIGH WIND CRITERIA
BEING MET TONIGHT.
AVIATION
BETWEEN MVFR AND IFR, WITH POSSIBLE LIFR THROUGH THIS TAF CYCLE.
A WINTRY MIX OF SNOW, FREEZING RAIN AND RAIN IS LIKELY AT TIMES THROUGH
09Z. LOOK FOR LOW CLOUDS TO LINGER INTO THURSDAY UNTIL GRADUAL
CLEARING FROM THE WEST ERODES IT AWAY.
WINDS WILL BE NORTHWEST AT 20 TO 30 KTS WITH GUSTS UP TO 50 KTS
THROUGH AROUND 12Z, DECREASING TO 10 - 20 KTS.
GGW WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL 5 AM MST THURSDAY FOR CENTRAL AND
SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY-DANIELS-DAWSON-
EASTERN ROOSEVELT-GARFIELD-MCCONE-NORTHERN PHILLIPS-NORTHERN
VALLEY-PETROLEUM-PRAIRIE-RICHLAND-SHERIDAN-SOUTHWEST PHILLIPS-
WESTERN ROOSEVELT-WIBAUX.
HIGH WIND WARNING UNTIL 11 AM MST THURSDAY FOR CENTRAL AND
SOUTHEAST PHILLIPS-CENTRAL AND SOUTHERN VALLEY-DANIELS-DAWSON-
EASTERN ROOSEVELT-GARFIELD-MCCONE-NORTHERN PHILLIPS-NORTHERN
VALLEY-PETROLEUM-PRAIRIE-RICHLAND-SHERIDAN-SOUTHWEST PHILLIPS-
WESTERN ROOSEVELT-WIBAUX.
COLD WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON MST THURSDAY
FOR DANIELS-NORTHERN PHILLIPS-NORTHERN VALLEY-SHERIDAN.
WEATHER.GOV/GLASGOW
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