506
FXUS65 KTFX 262351
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
551 PM MDT MON OCT 26 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- FOG WILL CONTINUE TO CLEAR OUT DURING THE AFTERNOON.
- A STORM SYSTEM WILL BRING LIGHT MOUNTAIN SNOW AND LIGHT
RAIN/SNOW AT LOWER ELEVATIONS LATE TONIGHT INTO TUESDAY
MORNING.
- COOLER AND AN SLIGHTLY UNSETTLED WEATHER PATTERN CONTINUES
THROUGH THE REST OF THE WEEK.
DISCUSSION
/ISSUED 220 PM MDT MON OCT 26 2026/
- METEOROLOGICAL OVERVIEW:
CURRENT SATELLITE TRENDS SHOW FOG AND LOWER CLOUDS ARE LIFTING
OUT OF SOUTHWEST MT AS WARMER AIR MIXES DOWN TO THE SURFACE.
ACROSS NORTH-CENTRAL MT, PATCHY DENSE FOG HAS LIFTED BUT LOWER
CLOUDS HAVE BEEN SLOWER TO DISSIPATE.
AN UPPER-LEVEL TROUGH BRINGING A LOW PRESSURE SYSTEM MOVES INTO
THE REGION LATER TODAY, BRINGING PRECIPITATION FROM THE SOUTHWEST
TO THE NORTH. WARM AIR ADVECTION AHEAD OF THE SYSTEM WILL BRING
RAIN INITIALLY, BUT A COLD FRONT WILL LOWER SNOW LEVELS,
TRANSITIONING TO LIGHT SNOW IN THE MOUNTAINS. SNOW LEVELS DO FALL
TOWARDS 4,000FT TO 4,500FT TUESDAY MORNING, BRINGING A LIGHT RAIN
TO SNOW MIX AT LOWER ELEVATIONS.
THROUGHOUT THE WEEK, MULTIPLE QUICK HITTING TROUGHS MOVE THROUGH
THE NORTHWEST, KEEPING DAILY CHANCES FOR PRECIPITATION THROUGH
THE REST OF THE WEEK AND INTO THE BEGINNING OF NEXT WEEK.
PRECIPITATION WILL BE MAINLY IN THE MOUNTAINS/PASSES WITH LIGHT
SNOW, ESPECIALLY ALONG THE NORTHERN CONTINENTAL DIVIDE. ISOLATED
RAIN/SNOW WILL BE POSSIBLE AT LOWER ELEVATIONS AT TIMES THROUGHOUT
THE WEEK. COOLER TEMPERATURES REMAIN THROUGH THE FORECAST PERIOD
DUE TO THE CONSISTENT TROUGHING PATTERN.
- FORECAST CONFIDENCE & SCENARIOS:
DENSE FOG AND LOWER CLOUDS ARE LIFTING OUT OF SOUTHWEST MT THIS
AFTERNOON AS THE WARM FRONT APPROACHES. THEREFORE, I WILL ALLOW
THE DENSE FOG ADVISORY TO EXPIRE AT 3PM. ANY LINGERING FOG THIS
AFTERNOON WILL BECOME MIXED OUT LATER IN THE DAY AS THE INCOMING
SYSTEM APPROACHES.
MESSAGING REMAINS CONSISTENT WITH THIS INCOMING SYSTEM TODAY INTO
TUESDAY. THERE'S A 30% CHANCE FOR 3" OF SNOW OR GREATER ABOVE
~6,000FT IN SOUTHWEST MT AND MARIAS PASS, KEEPING MINOR IMPACTS
FOR SNOW AT PASS AND ABOVE PASS LEVEL. ADDITIONAL ACCUMULATIONS
LATER THIS WEEK LOOK TO REMAIN LIGHT, WITH MARIAS PASS AT A 30%
CHANCE AGAIN FOR 3" OF SNOW ON WEDNESDAY. WET BULB TEMPERATURES
STRUGGLE TO REACH 32 DEGREES ACROSS LOWER ELEVATIONS EXCEPT FOR
THE HIGHER SOUTHWEST MT VALLEYS, THEREFORE ANY SNOW THAT DOES FALL
ALL LOWER ELEVATIONS WILL STRUGGLE TO ACCUMULATE. -WILSON
AVIATION
27/00Z TAF PERIOD
INITIAL CONCERN THIS TAF PERIOD WILL BE FOR A MIX OF RAIN AND SNOW
TO MOVE NORTHEASTWARD OUT OF SW MT AND VICINITY THIS EVENING INTO
THE OVERNIGHT TONIGHT. SW MT VALLEYS ARE THE MOST FAVORED TO SEE
SNOW MIX IN AT TIMES, WITH AREAS ON THE PLAINS SEEING A MUCH LOWER
PROBABILITY. SOME OF THIS PRECIPITATION WILL BE IN THE FORM OF
SHOWERS, THOUGH THE PROBABILITY FOR LIGHTNING WAS TOO LOW TO
MENTION IN ANY TAFS AT THIS TIME.
THIS PRECIPITATION DIMINISHES FOR THE MOST PART THROUGH TUESDAY
MORNING, AT WHICH POINT GUSTY SOUTHWEST TO WEST WINDS BEGIN TO
BUILD IN ACROSS ALL AREAS. AREAS ON THE PLAINS ARE MOST FAVORED
FOR THE GUSTIEST WINDS TUESDAY. MOUNTAINS WILL BECOME INCREASINGLY
OBSCURED THROUGH THE EVENING AND OVERNIGHT. -AM
PRELIMINARY POINT TEMPS/POPS
GTF 32 50 36 50 / 60 10 0 0
CTB 26 46 29 43 / 30 40 0 0
HLN 32 49 26 49 / 80 10 0 10
BZN 30 47 25 47 / 90 10 0 0
WYS 20 37 17 38 / 100 40 20 10
DLN 28 44 24 44 / 80 0 0 0
HVR 29 49 30 49 / 40 70 30 0
LWT 32 48 30 49 / 70 50 0 0
TFX WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 AM MDT
TUESDAY FOR GALLATIN AND MADISON COUNTY MOUNTAINS AND CENTENNIAL
MOUNTAINS.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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