937
FXUS65 KTFX 111722
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1122 AM MDT SUN OCT 11 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- SNOW WILL CONTINUE ACROSS THE AREA THROUGH MONDAY MORNING.
- IT WILL BE SIGNIFICANTLY COLDER ACROSS THE AREA ON SUNDAY AND MONDAY.
- TUESDAY THROUGH FRIDAY IT WILL GRADUALLY WARM UP WITH MOSTLY DRY
WEATHER.
DISCUSSION
/ISSUED 519 AM MDT SUN OCT 11 2026/
- METEOROLOGICAL OVERVIEW:
TODAY THERE IS AN UPPER-LEVEL TROUGH OVER MONTANA WITH MULTIPLE VORT
MAXES. THROUGH THE DAY TODAY IT WILL CONTINUE TO SNOW ACROSS NORTH-
CENTRAL AND CENTRAL MONTANA ENHANCED BY TROPICAL MOISTURE FROM
TROPICAL STORM RACHEL. TODAY ACROSS SOUTHWESTERN MONTANA IN THE
MOUNTAINS THERE WILL BE SNOW AND IN THE LOWER-ELEVATIONS THERE WILL
BE A RAIN/SNOW MIX. THERE REMAINS UNCERTAINTY IN HOW FAR SOUTH THE
COLDER AIR BEHIND THE COLD FRONT WILL MAKE IT. THIS WILL AFFECT
WHICH LOWER-ELEVATION AREAS SEE ANY SNOW DURING THE DAY TODAY.
SEE THE FORECAST CONFIDENCE AND SCENARIOS SECTION FOR DETAILS.
TODAY MOST AREAS OF NORTH-CENTRAL, AND SOUTHWESTERN MONTANA WILL
STRUGGLE TO GET ABOVE FREEZING. SUNDAY NIGHT SNOW-LEVELS WILL
LOWER ACROSS SOUTHWESTERN MONTANA. THIS WILL BRING PRIMARILY SNOW
TO ALL OF THE LOWER-ELEVATIONS OF SOUTHWESTERN MONTANA SUNDAY
NIGHT INTO MONDAY MORNING. ACROSS NORTH-CENTRAL AND CENTRAL
MONTANA SNOW WILL CONTINUE SUNDAY NIGHT THROUGH MONDAY MORNING. ON
MONDAY THE UPPER- LEVEL TROUGH SINKS FURTHER SOUTH. THIS WILL
ALLOW TEMPERATURES TO WARM UP A LITTLE ON MONDAY.
ON TUESDAY AND WEDNESDAY UPPER-LEVEL FLOW OVER MONTANA IS WEAK. THIS
WILL ALLOW TEMPERATURES TO WARM UP A FEW DEGREES EACH DAY. HOWEVER
THEY WILL REMAIN BELOW SEASONAL AVERAGES. ON THURSDAY AN UPPER-LEVEL
TROUGH BRIEFLY MOVES OVER MONTANA. THIS WILL SLIGHTLY COOL
TEMPERATURES AND BRING PRECIPITATION CHANCES TO THE AREA. ON FRIDAY
AND SATURDAY AN UPPER-LEVEL RIDGE MOVES OVER NORTH-CENTRAL, CENTRAL,
AND SOUTHWESTERN MONTANA. THIS WARM TEMPERATURES AND DRY WEATHER TO
THE AREA ON FRIDAY. -IG
- FORECAST CONFIDENCE & SCENARIOS:
FOR SNOW IN THE SOUTHWESTERN MONTANA VALLEYS, IT WILL DEPEND ON HOW
FAST COLD AIR MAKES IT DOWN THERE THIS MORNING. IN ADDITION WITH
WARM ROAD TEMPERATURES MOST OF THE SNOW THAT FALLS IN THE
SOUTHWESTERN MONTANA VALLEYS WILL MELT THROUGH THE DAY TODAY.
ADDITIONALLY, SNOW ACCUMULATIONS AT ALL LOWER-ELEVATIONS OF
NORTH- CENTRAL, CENTRAL, AND SOUTHWESTERN WILL VARY DRASTICALLY
FROM GRASSY/ELEVATED SURFACES TO ROADWAYS DUE TO WARM ROAD
TEMPERATURES. THE GREATEST IMPACTS FOR ANY SNOWFALL WILL BE EARLY
THIS MORNING AND SUNDAY NIGHT INTO EARLY MONDAY MORNING. ALL
SNOWFALL WILL BE WET AND HEAVY. THIS MEANS THAT IT ONLY WILL TAKE
A FEW INCHES OF SNOW TO CAUSE POWER OUTAGES AND/OR BREAK TREE
BRANCHES. THE TREE BRANCHES THAT ARE MOST SUSCEPTIBLE TO BREAKING
ARE THOSE THAT STILL HAVE LEAVES. CURRENTLY THE CURRENT WINTER
WEATHER PRODUCTS ARE CAPTURING THE CURRENT SITUATION WELL. THE ONE
EXCEPTION IS THE GALLATIN VALLEY. MOST OF THE HI-RES GUIDANCE IS
PREDICTING OVER 6 INCHES OF SNOWFALL WITH SEVERAL INCHES OF SNOW
DEPTH CHANGE IN THE GALLATIN VALLEY SUNDAY EVENING INTO MONDAY
MORNING. AS A RESULT THE GALLATIN VALLEY WAS UPGRADED TO A WINTER
STORM WARNING FROM 6 PM SUNDAY TO 9 AM MONDAY.
TODAY ACROSS THE NORTH-CENTRAL MONTANA PLAINS ALONG AND EAST OF I-15
THERE IS A 30 - 70% CHANCE FOR HIGH TEMPERATURES OF 36 DEGREES OR
COLDER. TUESDAY MORNING ACROSS THE NORTH-CENTRAL MONTANA PLAINS
ALONG AND EAST OF I-15 AND ACROSS THE VALLEYS OF SOUTHWESTERN
MONTANA THERE IS A 50 - 80% CHANCE FOR TEMPERATURES OF 20 DEGREES OR
COLDER. -IG
AVIATION
11/18Z TAF PERIOD
WIDESPREAD SNOWFALL WILL CONTINUE ACROSS ALL TERMINALS THE
EXCEPTION OF KWYS WHICH WILL START INITIALLY AS RAINFALL BEFORE
SWITCH TO SNOW IN THE LATER HALF OF THE TAF PERIOD. WIDESPREAD LOW
CEILINGS AND VISIBILITIES WILL CONTINUE THROUGHOUT MUCH OF THE
PERIOD WITH MODEST IMPROVEMENTS TOWARDS THE VERY END OF THE TAF
PERIOD AS OUR LOW PRESSURE SYSTEM CONTINUES TO MOVE EAST. MOUNTAIN
OBSCURATION WILL CONTINUE. -JR
PRELIMINARY POINT TEMPS/POPS
GTF 33 27 36 22 / 100 100 40 0
CTB 30 22 35 19 / 100 100 40 0
HLN 32 25 39 23 / 100 100 20 0
BZN 34 22 39 20 / 100 100 10 0
WYS 46 21 48 21 / 100 100 60 10
DLN 32 23 39 21 / 100 100 10 0
HVR 39 23 42 20 / 100 100 60 0
LWT 36 24 38 23 / 100 100 40 0
TFX WATCHES/WARNINGS/ADVISORIES
WINTER STORM WARNING UNTIL 6 AM MDT MONDAY FOR BIG BELT, BRIDGER
AND CASTLE MOUNTAINS-CASCADE COUNTY BELOW 5000FT-EAST GLACIER
PARK REGION-EASTERN PONDERA AND EASTERN TETON-ELKHORN AND
BOULDER MOUNTAINS-GATES OF THE MOUNTAINS-JUDITH BASIN COUNTY AND
JUDITH GAP-LITTLE BELT AND HIGHWOOD MOUNTAINS-MEAGHER COUNTY
VALLEYS-NORTHERN HIGH PLAINS-SNOWY AND JUDITH MOUNTAINS-SOUTHERN
HIGH PLAINS-SOUTHERN ROCKY MOUNTAIN FRONT-UPPER BLACKFOOT AND
MACDONALD PASS.
WINTER WEATHER ADVISORY UNTIL 6 AM MDT MONDAY FOR BEARS PAW
MOUNTAINS AND SOUTHERN BLAINE-BEAVERHEAD AND WESTERN MADISON
BELOW 6000FT-CANYON FERRY AREA-EASTERN GLACIER, WESTERN TOOLE,
AND CENTRAL PONDERA-EASTERN TOOLE AND LIBERTY-FERGUS COUNTY
BELOW 4500FT-GALLATIN AND MADISON COUNTY MOUNTAINS AND
CENTENNIAL MOUNTAINS-HELENA VALLEY-MADISON RIVER VALLEY-MISSOURI
HEADWATERS-NORTHWEST BEAVERHEAD COUNTY-RUBY MOUNTAINS AND
SOUTHERN BEAVERHEAD MOUNTAINS-WESTERN AND CENTRAL CHOUTEAU
COUNTY.
WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR GALLATIN
VALLEY.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 9 AM MDT MONDAY
FOR GALLATIN VALLEY.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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