012
FXUS65 KTFX 122151
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
251 PM MST FRI DEC 12 2025
KEY MESSAGES
- HEAVY SNOW WILL CONTINUE ACROSS PORTIONS OF NORTH-CENTRAL AND
CENTRAL MONTANA THROUGH THE NIGHT.
- LIGHT MIXED PRECIPITATION AND FREEZING RAIN IS POSSIBLE ACROSS
PORTIONS CENTRAL MONTANA THROUGH TONIGHT WITH ACCUMULATIONS UP
TO A LIGHT GLAZE POSSIBLE.
- A COLD AIRMASS REMAINS OVER THE PLAINS THROUGH SATURDAY BEFORE
WINDIER AND WARMER CONDITIONS DEVELOP LATE THIS WEEKEND INTO
EARLY NEXT WEEK.
DISCUSSION
- METEOROLOGICAL OVERVIEW:
A BAND OF MODERATE TO HEAVY SNOW WILL PERSIST OVER PORTIONS OF
NORTH-CENTRAL AND CENTRAL MONTANA THROUGH THE OVERNIGHT HOURS
BRINGING LOCALLY HEAVY SNOW AND MODERATE TO HEAVY SNOWFALL RATES.
IMPACTS TO TRAVEL AND INFRASTRUCTURE ARE POSSIBLE AND THOSE
HEADING OUT SHOULD BE PREPARED FOR RAPIDLY DETERIORATING ROAD AND
WEATHER CONDITIONS.
ALONG THE FRINGES OF PRECIPITATION THERE IS A CONCERN FOR LIGHT
FREEZING RAIN ACROSS PORTIONS OF CENTRAL MONTANA WHERE
ACCUMULATION UP TO A LIGHT GLAZE IS POSSIBLE. TRAVEL MAY BECOME
HAZARDOUS FOR MUCH OF THE REGION THROUGH THE OVERNIGHT HOURS.
OVERNIGHT LOWS FROM 15 BELOW TO 10 ABOVE ARE EXPECTED ACROSS THE
PLAINS OF NORTH-CENTRAL MONTANA THIS EVENING WHILE THE VALLEYS OF
CENTRAL AND SOUTHWEST MONTANA WILL REMAIN CLOSER TO FREEZING.
THROUGH THE WEEKEND THE UPPER LEVEL RIDGE WILL SHIFT SLIGHTLY
EASTWARD WHICH WILL HELP TO PUSH OUT THE COLDER AIRMASS AND ALLOW
FOR WARMER AND WINDIER CONDITIONS TO RETURN TO THE REGION THROUGH
AT LEAST
- FORECAST CONFIDENCE & SCENARIOS:
HEAVY SNOW CONTINUES ACROSS NORTH-CENTRAL MONTANA:
THE SNOWBAND IS FULLY UNDERWAY ACROSS PORTIONS OF NORTH-CENTRAL
AND CENTRAL MONTANA THIS AFTERNOON WITH THE HEAVIEST SNOW ROUGHLY
STRETCHING FROM THE CHESTER/INVERNESS AREA DOWN TO CUSTER. AS THE
EVENING PROGRESSES THIS BAND IS EXPECTED TO SLOWLY MARCH TO THE
NORTHEAST WITH THE AXIS OF HEAVIEST SNOW RESTING ON A LINE BETWEEN
HAVRE AND TERRY. AN ADDITIONAL 4 TO 6 INCHES IS POSSIBLE ACROSS
THE LOWER ELEVATIONS OF HILL, BLAINE, AND NORTHERN FERGUS COUNTIES
WITH UP TO 10 INCHES POSSIBLE IN THE BEARS PAW. LOCALLY HIGHER
AMOUNTS ARE POSSIBLE UNDER HEAVIER PORTIONS OF THE SNOWBAND.
AS IT HAS BEEN STATED IN PREVIOUS MESSAGING, THERE MAY BE A SHARP
SNOWFALL ACCUMULATION GRADIENT AS A RESULT OF THE SNOWBAND WHERE
LOCATIONS DIRECTLY UNDER THE SNOWBAND MAY RECEIVE THE FULL
FORECASTED AMOUNT, AND POTENTIALLY MORE, WHILE LOCATIONS JUST
OUTSIDE THE SNOWBAND MAY EXPERIENCE MUCH LESS SNOWFALL.
THE MAIN CONCERN WILL BE SLIPPERY ROADS AND REDUCED VISIBILITY
DUE TO HEAVY SNOWFALL RATES AND THE POTENTIAL FOR BLOWING SNOW
ACROSS THE HI-LINE. ADDITIONALLY, PERIODS OF BLOWING SNOW MAY LEAD
TO SOME PATCHY SNOW DRIFTS ALONG AREA ROADS INCLUDING HIGHWAY 2
AND HIGHWAY 66 WHICH MAY MAKE TRAVEL DIFFICULT AT TIMES.
THIS SNOWBAND WILL SLOWLY START TO TAPER OFF EARLY SATURDAY
MORNING AND THE HEAVIEST SNOW IS EXPECTED TO END BY AROUND 4 TO 6
AM. LIGHT SNOW SHOWERS MAY LINGER IN THE AREA, PARTICULARLY ALONG
THE ISLAND MOUNTAIN RANGES. BUT BY SATURDAY AFTERNOON, A RETURN TO
CALMER CONDITIONS IS EXPECTED.
MIXED PRECIPITATION/FREEZING RAIN TONIGHT:
WITH A SHALLOW WARM LAYER ALOFT OVER PORTIONS OF CENTRAL MONTANA
THERE IS A CONCERN FOR FREEZING RAIN ALONG PORTIONS OF HIGHWAY 200
FROM GREAT FALLS TO LEWISTOWN, I-15 FROM GREAT FALLS TO HELENA AND
HIGHWAY 287 FROM HELENA TO TOSTON. LIGHT FREEZING RAIN HAS ALREADY
BEEN REPORTED SOUTH OF GREAT FALLS ALTHOUGH ICE ACCUMULATIONS HAVE
BEEN VERY MINIMAL AT BEST SO FAR. THE BIGGEST CONCERN IS THAT AS
SOON AS THE SUN SETS TONIGHT THE ROADS WILL START TO FREEZE UP
WHICH COULD CREATE A DANGEROUS SITUATION EVEN IF PRECIPITATION
HAS ENDED.
WHEN CONSIDERING THE POTENTIAL FOR ADDITIONAL ADVISORIES/WARNINGS,
THERE IS NOT CURRENTLY ENOUGH CONFIDENCE IN SIGNIFICANT ICE
ACCUMULATIONS TO ADD AN ADDITIONAL WINTER WEATHER ADVISORY AT TIME
TIME. HOWEVER THIS WILL BE MONITORED VERY CLOSELY OVER THE NEXT
FEW HOURS AS EVEN A SLIGHT UPTICK IN FREEZING RAIN AMOUNTS BEYOND
WHAT IT CURRENT FORECASTED AND EXPECTED COULD QUICKLY CAUSE
DANGEROUS ROAD CONDITIONS ACROSS PORTIONS OF CENTRAL MONTANA.
IN THE MEANTIME, MOTORISTS NEED TO BE PREPARED FOR SUDDEN CHANGES
TO ROAD CONDITIONS AND KEEP IN MIND THAT ICE CAN BE ALMOST
IMPOSSIBLE TO SEE AT NIGHT. IF POSSIBLE, FOLKS SHOULD DELAY TRAVEL
AT LEAST UNTIL TEMPERATURES WARM UP LATE TOMORROW MORNING TO AVOID
PUTTING THEMSELVES IN A POTENTIALLY HAZARDOUS SITUATION.
BITTER COLD ALONG THE HI-LINE:
ANOTHER ROUND OF SUB-ZERO LOWS IS EXPECTED ACROSS THE HI-LINE
TONIGHT WITH THE COLDEST TEMPERATURES EXPECTED IN NORTHERN BLAINE
COUNTY. A COLD WEATHER ADVISORY HAS BEEN ISSUED FOR NORTHERN BLAINE
OVERNIGHT AS APPARENT TEMPERATURES COULD DROP AS LOW AS 30 BELOW,
ESPECIALLY OUT TOWARDS THE TURNER AREA.
TEMPERATURES WILL WARM UP INTO THE SINGLE DIGITS ABOVE ZERO SATURDAY
MORNING WITH ONE MORE ROUND OF COLD TEMPERATURES EXPECTED SATURDAY
NIGHT INTO SUNDAY MORNING BEFORE A WARM FRONT IS ABLE TO ADVANCE
TOWARDS THE HI-LINE. WITH THE WARM FRONT EXPECTED TO ARRIVE
OVERNIGHT, THERE IS LOWER CONFIDENCE THAT OUR PORTION OF THE HI-LINE
WILL REACH ADVISORY CRITERIA AGAIN. HOWEVER THERE ARE THREE FACTORS
AT PLAY THAT COULD EASILY NUDGE THE SITUATION IN EITHER DIRECTION.
THE FIRST IS THE LOCATION AND PROGRESSION OF THE WARM FRONT, THE
WIND SPEEDS, WHICH ARE CURRENTLY EXPECTED TO REMAIN LIGHT AND
VARIABLE, AND THE FINAL SNOWPACK IN THE REGION AFTER THE SNOWBAND
HAS DISSIPATED. IF ANY OF THESE FACTORS DEVIATES FROM WHAT IS
CURRENTLY EXPECTED IN THE FORECAST THEN AN ADVISORY MAY NEED TO BE
CONSIDERED FOR NORTHERN BLAINE COUNTY SATURDAY NIGHT INTO SUNDAY.
BUT FOR NOW, CONFIDENCE IS TOO LOW IN REACHING ADVISORY LEVEL
TEMPERATURES TO WARRANT EXTENDING THE CURRENT ADVISORY THROUGH
SUNDAY MORNING.
WARMER TEMPERATURES RETURN:
BOTH THE GFS AND EURO ENSEMBLES ARE IN AGREEMENT THAT TEMPERATURES
WILL WARM BACK INTO 40S AND 50S ACROSS THE LOWER ELEVATIONS THROUGH
AT LEAST THE MIDDLE OF NEXT WEEK. WHAT HAPPENS CLOSER TO CHRISTMAS
ENDS UP BEING A BIT OF A WILD CARD AS THERE ARE SOME SUGGESTIONS IN
THE ENSEMBLES THAT ANOTHER COLDER AND ACTIVE PERIOD COULD RETURN TO
THE REGION. BUT GIVEN HOW FAR OUT THIS IS, NO FINER DETAILS WILL BE
RESOLVED AT THIS POINT IN TIME.
-THOR
AVIATION
12/18Z TAF PERIOD
SNOW WILL CONTINUE TO END FROM SOUTHWEST TO NORTHEAST ACROSS
SOUTHWEST AND CENTRAL MONTANA TERMINALS OF KBZN, KHLN, AND KGTF
THROUGH 21Z FRIDAY AND THE KLWT TERMINAL THROUGH 01Z SATURDAY. AS
THE SNOW SHIFTS TO THE NORTHEAST EXPECT CIGS TO IMPROVE ACROSS THE
KEKS, KBZN, AND KHLN TERMINALS TO MAINLY LOW-VFR/VFR FOR THE
REMAINDER OF THE 1218/1318 TAF PERIOD, WITH PLAINS TERMINALS OF
CENTRAL AND NORTH CENTRAL MONTANA (I.E. KCTB, KHVR, KGTF, AND
KLWT) REMAINING LIFR/IFR/MVFR. SNOW WILL PERSIST OVER THE KCTB AND
KHVR TERMINALS FOR MUCH OF THE NEXT 24 HOURS, WITH WIDESPREAD
MOUNTAIN OBSCURATION EXPECTED ACROSS THE NORTHERN ROCKIES INTO THE
DAY ON SATURDAY. - MOLDAN
PRELIMINARY POINT TEMPS/POPS
GTF 6 34 22 50 / 30 20 0 0
CTB -1 27 15 46 / 60 10 0 0
HLN 27 42 28 51 / 10 10 0 0
BZN 33 49 26 54 / 0 0 0 0
WYS 19 37 12 44 / 0 0 0 0
DLN 32 51 28 53 / 0 0 0 0
HVR -7 7 1 43 / 100 10 0 0
LWT 5 31 21 49 / 60 30 0 0
TFX WATCHES/WARNINGS/ADVISORIES
WINTER STORM WARNING UNTIL 5 AM MST SATURDAY FOR BEARS PAW
MOUNTAINS AND SOUTHERN BLAINE-EASTERN TOOLE AND LIBERTY-FERGUS
COUNTY BELOW 4500FT-HILL COUNTY-JUDITH BASIN COUNTY AND JUDITH
GAP-NORTHERN BLAINE COUNTY-WESTERN AND CENTRAL CHOUTEAU COUNTY.
WINTER WEATHER ADVISORY UNTIL 5 AM MST SATURDAY FOR EASTERN
GLACIER, WESTERN TOOLE, AND CENTRAL PONDERA-EASTERN PONDERA AND
EASTERN TETON-NORTHERN HIGH PLAINS.
COLD WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 10 AM MST
SATURDAY FOR NORTHERN BLAINE COUNTY.
WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR LITTLE BELT
AND HIGHWOOD MOUNTAINS-SNOWY AND JUDITH MOUNTAINS.
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