458
FXUS65 KTFX 210543
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1143 PM MDT TUE OCT 20 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- TEMPERATURES WILL RETURN TO UNSEASONABLY WARM LEVELS ON
WEDNESDAY AND CONTINUE UNTIL A PERIOD OF COOLER THAN AVERAGE
TEMPERATURES BEGINS FRIDAY, WHICH CONTINUES THROUGH THE
BEGINNING OF THE FOLLOWING WEEK.
- PACIFIC SYSTEM WILL BRING RAIN AND MOUNTAIN SNOW BEGINNING
THURSDAY NIGHT AND CONTINUING THROUGH EARLY SATURDAY MORNING.
- GUSTY WINDS DEVELOP FRIDAY AFTERNOON AND CONTINUE THROUGH
FRIDAY NIGHT WITH THE HIGHEST GUSTS ALONG THE ROCKY MOUNTAIN
FRONT AND CENTRAL MT.
UPDATE
/ISSUED 738 PM MDT TUE OCT 20 2026/
SATELLITE IMAGERY THIS EVENING SHOWS AREAS OF MAINLY THIN HIGH
CLOUD-COVER STREAMING ACROSS MT IN WEST TO SOUTHWEST FLOW ALOFT
AROUND THE CIRCULATION OF AN UPPER LEVEL RIDGE CENTERED SOUTHEAST
OF THE AREA. OVERALL DRY CONDITIONS AND LIGHT WINDS PREVAIL
THROUGH THE REMAINDER OF TONIGHT AS SURFACE HIGH PRESSURE SLIDES
EAST ACROSS THE CANADIAN PRAIRIES. HOENISCH
DISCUSSION
/ISSUED 738 PM MDT TUE OCT 20 2026/
- METEOROLOGICAL OVERVIEW:
UPPER-LEVEL RIDGING WILL ALLOW FOR MILD CONDITIONS TO CONTINUE
THROUGH THURSDAY. TEMPERATURES WILL BE WARMER THAN AVERAGE AND WINDS
WILL BE LIGHTER WITH GUSTS GENERALLY REMAINING UNDER 25 MPH.
A WEATHER SYSTEM OUT OF THE PACIFIC THAT HAS BEEN LINGERING OVER THE
WEST COAST WILL BEGIN TO TRACK EASTWARD ON THURSDAY, BRINGING COOLER
TEMPERATURES AND MOISTURE TO THE AREA. A COLD FRONT ASSOCIATED WITH
THIS SYSTEM WILL MOVE THROUGH THE REGION ON FRIDAY, RESULTING IN THE
HIGH TEMPERATURES ON FRIDAY TO OCCUR DURING THE MORNING HOURS.
ADDITIONALLY, POST FRONTAL WINDS WILL DEVELOP FRIDAY AFTERNOON AND
CONTINUE THROUGH FRIDAY NIGHT. THE HIGHEST GUSTS ARE EXPECTED ALONG
THE ROCKY MOUNTAIN FRONT AND CENTRAL MOUNTAINS. FOR SOUTHWEST
MONTANA, THERE IS ALSO A CHANCE FOR THUNDERSTORMS DUE TO PASSING OF
THE COLD FRONT DURING THE DAY ON FRIDAY. DUE TO SNOW LEVELS NOT
FALLING UNTIL THE PRECIPITATION ASSOCIATED WITH THIS SYSTEM HAS
DECREASED, THE BULK OF SNOWFALL IS LIKELY TO BE LIMITED TO THE
MOUNTAINS. ANY SNOWFALL THAT DOES MIX-IN FOR THE LOWLAND AREAS WILL
BE HINDERED IN ACCUMULATING DUE TO RECENT RAINFALL AND WARM
TEMPERATURES.
LOOKING BEYOND SATURDAY, ALTHOUGH CONFIDENCE IS LOWER DUE TO THE HOW
FAR INTO THE FUTURE THIS IS, UPPER-LEVEL TROUGHING LOOKS LIKE IT
WILL REMAIN IN PLACE OVER THE REGION. OVERALL, TEMPERATURES WILL
CONTINUE TO BE COOLER WITH OVERNIGHT FREEZES EACH NIGHT. WINDS
WILL BE MILD ACROSS THE REGION WITH GUSTS GENERALLY UNDER 25 MPH.
AN UPPER-LEVEL TROUGH HAS THE POTENTIAL TO CLIP NORTH MONTANA ON
SUNDAY AND CAUSE SOME LIGHT SHOWERS. WITH SNOW LEVELS STILL AT
LOWER LEVELS AND DAYTIME HIGH TEMPS IN THE UPPER 30S/LOW 40S,
LIGHT SHOWERS MAY BE SNOW OR A SNOW/RAIN MIX IN THE LOWLANDS. -ESH
- FORECAST CONFIDENCE & SCENARIOS:
HIGH CONFIDENCE FOR AREAS OF MOUNTAIN SNOWFALL THURSDAY NIGHT
THROUGH SATURDAY MORNING. 60-80% CHANCE OF 2" OR MORE DURING THAT
TIME FRAME. MAIN AREAS IMPACTED WILL BE THE NORTHERN ROCKIES, ISLAND
MOUNTAINS, AND SW MONTANA MOUNTAINS.
MEDIUM CONFIDENCE FOR WHETHER THERE WILL BE SNOWFALL IN LOWLAND
AREAS ON FRIDAY NIGHT AND SATURDAY DUE TO AN OFFSET IN SNOW LEVELS
FALLING AND PRECIPITATION TIMING. CURRENTLY THERE IS A <30% CHANCE
FOR A TRACE OF SNOWFALL IN LOWLAND AREAS. -ESH
A POSSIBLE ALTERNATE SCENARIO THAT WOULD ALLOW FOR MORE LOWLAND
SNOW: THE LOW/TROUGH PHASING IS SLOWER, BOTH DELAYING THE
PROGRESSION OF THE TROUGHING BUT ALSO ALLOWING DEFORMATION MOISTURE
TO LINGER ACROSS THE AREA WHILE COLD AIR DRIVES SNOW LEVELS DOWN
TOWARDS 3KFT. THIS WILL INTRODUCE A WINDOW FOR A MORE PERSISTENT BUT
LIGHT SNOWFALL ACROSS LOWER ELEVATIONS. THAT BEING SAID, WARM GROUND
TEMPERATURES AND HOURS OF RAIN PROCEEDING THE POTENTIAL CHANGE WOULD
RESTRICT ANY OF THIS TO ELEVATED SURFACE IF ANY AT ALL. -JR
AVIATION
21/06Z TAF PERIOD
VFR CONDITIONS PREVAIL THROUGH THE TAF PERIOD. SURFACE WINDS WILL
REMAIN FAIRLY LIGHT, INCREASING INTO THE AFTERNOON HOURS AREA
WIDE. FEW TO SCATTERED MID-LEVEL CLOUDS WILL BE PREVALENT THROUGH
THE TAF PERIOD. ACROSS SOUTHWEST MONTANA, A FEW CUMULUS DURING
THE PEAK HEATING HOURS ARE POSSIBLE WHICH MAY BRING SLIGHTLY LOWER
CLOUD BASES. -JR
PRELIMINARY POINT TEMPS/POPS
GTF 57 37 73 45 / 0 0 0 0
CTB 56 31 68 39 / 0 0 0 0
HLN 62 35 69 40 / 0 0 0 0
BZN 64 34 67 38 / 0 0 0 0
WYS 61 28 60 30 / 10 0 20 0
DLN 66 36 65 38 / 0 0 0 10
HVR 60 32 69 38 / 0 0 0 0
LWT 60 35 71 45 / 0 0 0 0
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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