491
FXUS65 KTFX 140955
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
355 AM MDT TUE OCT 14 2025
KEY MESSAGES
- GENERAL COOL, DAMP, AND MOSTLY CLOUDY CONDITIONS CONTINUE TODAY WITH
A FEW AREAS OF PASSING LIGHT RAIN, SNOW, AND OR MIXED
PRECIPITATION EXPECTED.
- ANOTHER PACIFIC WEATHER SYSTEM WILL BRING PERIODS OF RAIN
SHOWERS AND MOUNTAIN SNOW WEDNESDAY THROUGH EARLY FRIDAY,
ESPECIALLY OVER SOUTHWEST MT.
- PERIODS OF BREEZY TO WINDY CONDITIONS AND MILD TEMPERATURES ARE
EXPECTED HEADING INTO THE WEEKEND.
DISCUSSION
- METEOROLOGICAL OVERVIEW:
THE COMBINATION OF MILD AND MOIST SOUTHWESTERLY FLOW OVERRUNNING
COLD LOW LEVEL EAST TO NORTHEASTERLY FLOW HAS RESULTED IN ABUNDANT
PATCHY FOG, SCATTERED AREAS OF LIGHT SNOW, AND EVEN SOME
DRIZZLE/FREEZING DRIZZLE. THIS GENERAL PATTERN WILL CONTINUE OVER
THE NEXT COUPLE OF DAYS, BUT GRADUALLY WARMING TEMPERATURES ARE
EXPECTED TO LIMIT THE IMPACTS FROM SNOW AND FREEZING
PRECIPITATION. THERE MAY EVEN BE A FEW THUNDERSTORMS AND OR BURSTS
OF HEAVIER SNOW SHOWERS OVER THE SOUTHWEST THIS AFTERNOON AND
EVENING.
THE ELONGATED MID-LEVEL TROUGH, RESPONSIBLE FOR THE SOUTHWESTERLY
FLOW ALOFT, STRETCHES SOUTHWESTWARD INTO CENTRAL CA WHERE A
CLOSED CIRCULATION WILL BEGIN TO SWING NORTHEASTWARD THROUGH THE
GREAT BASIN AND EVENTUALLY INTO EASTERN MT BY THURSDAY EVENING.
MOST ENSEMBLES HIGHLIGHT THIS SYSTEM MERGING WITH ANOTHER TROUGH
DIVING SOUTHEASTWARD THROUGH BC/AB THURSDAY NIGHT INTO FRIDAY.
THIS WILL BRING THE BEST CHANCE FOR WIDESPREAD LOWER ELEVATION
RAIN AND MOUNTAIN SNOW WEDNESDAY THROUGH EARLY FRIDAY. WITH MILDER
PACIFIC AIR MOVING IN, SNOW IMPACTS LOOK TO BE ON THE MINOR SIDE
AND MOSTLY CONFINED TO MOUNTAIN AREAS. MOST OF THE PRECIPITATION
IS EXPECTED TO FALL EAST OF A DILLON TO HAVRE LINE AND THE PRIMARY
AREA OF CONCERN WILL BE SNOW IN THE MADISON AND GALLATIN MOUNTAIN
RANGES.
THE CANADIAN TROUGH MERGING ON THE BACK SIDE OF THIS SYSTEM WILL
BRING STRONG NORTHWESTERLY FLOW ALOFT AND BREEZY TO WINDY
CONDITIONS THURSDAY NIGHT THROUGH SATURDAY BEFORE A BRIEF PERIOD
OF RIDGING FOR DRIER AND MILDER CONDITIONS MOVE IN THIS WEEKEND.
ANOTHER TROUGH LOOKS TO MOVE IN LATE SUNDAY INTO EARLY NEXT WEEK,
BUT THE PRECISE EVOLUTION OF THIS SYSTEM IS UNCERTAIN AT THIS
TIME. - RCG
- FORECAST CONFIDENCE & SCENARIOS:
RAIN AND SNOW WEDNESDAY THROUGH EARLY FRIDAY...
THE CURRENT PATH OF THE TROUGH RESPONSIBLE FOR THE RAIN AND SNOW
EXPECTED WEDNESDAY THROUGH FRIDAY FAVORS THE MOST WIDESPREAD
PRECIPITATION TO FALL MOSTLY EAST OF A DILLON TO HAVRE LINE. THESE
AREAS CURRENTLY HAVE A 30 TO 60% CHANCE FOR RAINFALL/LIQUID
EQUIVALENT PRECIPITATION AMOUNTS EXCEEDING A HALF INCH FOR THE 48
HOUR PERIOD ENDING FRIDAY AT 6 AM, OF COURSE WITH MOUNTAIN AREAS
BOASTING THE GREATEST PROBABILITIES. SOME DETERMINISTIC MODELS,
NAMELY THE NAM, HAVE BEEN BRINGING HEAVIER PRECIPITATION AND LOWER
ELEVATION SNOWFALL TOTALS FARTHER NORTH INTO CENTRAL MT, BUT WITH
MID- AND UPPER LEVEL TEMPERATURES RUNNING ON THE WARM SIDE,
GENERALLY AROUND 0C AT 700 MB, THOSE SOLUTIONS SEEM A BIT
UNREALISTIC. SNOWFALL PROBABILISTIC GUIDANCE ALSO REFLECTS THE
WARMER TEMPERATURES WITH ONLY THE MADISON AND GALLATIN RANGES
ABOVE 6,000 FT SEEING A 50 TO 70% CHANCE FOR SNOW TOTALS OVER 3
INCHES FOR THE SAME 48 HOUR PERIOD ENDING AT 6 AM FRIDAY. THERE IS
ALSO SOME UNCERTAINTY TO SORT OUT IN REGARDS OF SECOND TROUGH
DIVING SOUTHEASTWARD OUT OF CANADA BEING MORE INFLUENTIAL AND
SHIFTING THE PRECIPITATION EVEN FARTHER EAST THAN CURRENT
PROJECTIONS. THIS SITUATION WILL BE MONITORED IN THE COMING DAYS.
- RCG
AVIATION
14/06Z TAF PERIOD
LOW STRATUS CLOUDS WILL CONTINUE TO BUILD IN OVERNIGHT AND THROUGH
THE MORNING. MVFR TO IFR CIGS ARE LIKELY WITH ISOLATED LIFR.
PATCHY FOG WILL CONTINUE ACROSS THE REGION THROUGH TUESDAY
MORNING, WITH A SLIGHT CHANCE FOR LOCALLY DENSE FOG. WEST
YELLOWSTONE IS THE EXCEPTION, WITH IT LIKELY TO HAVE DENSE FOG
THROUGH TUESDAY MORNING. LIGHT SNOW LINGERS ACROSS NORTH CENTRAL
MT DURING THE OVERNIGHT HOURS. THERE IS AN ISOLATED CHANCE FOR
BRIEF FREEZING DRIZZLE AS WELL, BUT CONFIDENCE IN PINPOINTING IT
IMPACTING A SPECIFIC TERMINAL IS LOW. ANOTHER WAVE OF
PRECIPITATION FROM ID WILL LIFT NORTH INTO SOUTHWEST MT TUESDAY
MORNING, BRINGING LIGHT SNOW/WINTRY MIX AND RAIN. THERE IS SOME
UNCERTAINTY IN THE TIMING OF THIS WAVE, AND IF AFTERNOON
THUNDERSTORMS WILL IMPACT TERMINALS. THERE WILL BE MOUNTAIN
OBSCURATION FROM LOW CLOUDS AND PRECIPITATION. -WILSON
PRELIMINARY POINT TEMPS/POPS
GTF 39 29 46 34 / 20 20 30 40
CTB 39 23 49 29 / 20 20 10 20
HLN 42 29 45 33 / 20 40 50 50
BZN 48 30 48 31 / 40 60 60 70
WYS 52 28 46 27 / 60 80 90 80
DLN 47 32 48 32 / 50 50 60 60
HVR 46 30 50 35 / 20 20 40 50
LWT 46 29 47 33 / 20 40 50 70
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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