676
FXUS65 KTFX 102326
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
526 PM MDT SAT OCT 10 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- TWO WAVES OF IMPACTFUL SNOWFALL DEVELOP THIS WEEKEND INTO MONDAY
AS TEMPERATURES TREND SIGNIFICANTLY COOLER ACROSS THE REGION.
- INITIAL CONCERN THROUGH THE DAY TODAY AND INTO TONIGHT WILL BE
ALONG THE ROCKY MOUNTAIN FRONT AND ACROSS CENTRAL MONTANA.
- CONCERN FOR HEAVY SNOWFALL EXPANDS FURTHER SOUTH INTO SOUTHWEST
MONTANA SUNDAY INTO SUNDAY NIGHT.
DISCUSSION
/ISSUED 1242 PM MDT SAT OCT 10 2026/
- METEOROLOGICAL OVERVIEW:
A COMPLEX EVOLUTION TO THE UPPER LEVEL PATTERN WILL CONTINUE
THROUGH TODAY, INITIALLY WITH A LARGE UPPER LEVEL TROUGH WITH
MULTIPLE EMBEDDED VORT MAXES SINKING SOUTHWARD FROM THE PACIFIC
NORTHWEST, ELONGATING AS IT DOES SO. AT THE SURFACE AN AREA OF LOW
PRESSURE CENTERED IN NORTH DAKOTA HAS PULLED A COLD FRONT
SOUTHWARD ACROSS THE PLAINS EARLY THIS MORNING. THE COMBINATION OF
THIS FRONT, FAVORABLE FORCING, AND AMPLE MOISTURE HAS RESULTED IN
A ROUND OF PRECIPITATION DEVELOPING ACROSS MUCH OF NORTH CENTRAL
AND CENTRAL MONTANA. PRECIPITATION IN THE FORM OF RAIN ACROSS
MANY AREAS WILL CONTINUE TO TRANSITION TO SNOW AS COLD AIR
ADVECTION NEAR THE SURFACE WINS OUT. A PRECIPITATION TRANSITIONS
TO SNOW EXPECT THE SNOW CHARACTERISTIC TO BE OF THE WET AND HEAVY
VARIETY, ESPECIALLY AT LOWER ELEVATIONS, WHICH RAISES CONCERN FOR
TREES WITH LEAVES ON THEM STILL SEEING SNAPPED BRANCHES,
POTENTIALLY IMPACTING POWER LINES. - AM/MOLDAN
COLDER AIR CONTINUES TO SINK SOUTHWARD INTO SOUTHWEST MONTANA
HEADING INTO SUNDAY, THOUGH THERE REMAINS SOME UNCERTAINTY WITH
RESPECT TO JUST HOW FAR IT MAKES IT. ALOFT THE COMPLEX EVOLUTION
CONTINUES, WITH THE UPPER LEVEL TROUGHING ELONGATING FURTHER, WHILE
ALSO INTERACTING WITH THE REMNANTS OF RACHEL AS THEY LIFT
NORTHEASTWARD AHEAD OF THE TROUGH AXIS. AMPLE MOISTURE ASSOCIATED
WITH NOT ONLY THE MAIN TROUGHING, BUT THE REMNANTS OF RACHEL WILL
SUPPORT THE EXPANSION OF PRECIPITATION SOUTHWARD INTO SOUTHWEST
MONTANA DURING THE DAY SUNDAY AS AN UPPER LEVEL JET MOVES OVERHEAD.
THE EXTENT OF IMPACTFUL SNOWFALL ACROSS SOUTHWEST MONTANA WILL
FOLLOW WHERE THE COLDEST AIR BOTH ALOFT AND AT THE SURFACE ENDS UP
SETTLING. BANDED PRECIPITATION LOOKS TO PERSISTS INTO MONDAY
MORNING ACROSS PORTIONS OF CENTRAL AND SOUTHWEST MONTANA BEFORE
SUBSIDING THROUGH THE DAY.
THE REGION LOOKS TO DRY OUT FOR AT LEAST A COUPLE DAYS AS THE UPPER
LEVEL TROUGHING CONSOLIDATES ONCE AGAIN ACROSS THE DESERT SOUTHWEST.
UNCERTAINTY GROWS A BIT TOWARD THURSDAY, THOUGH THE MAJORITY OF
ENSEMBLE MEMBERS REMAIN DRY THURSDAY TOWARD THE WEEKEND. -AM
- FORECAST CONFIDENCE & SCENARIOS:
SNOWFALL THROUGH SUNDAY NIGHT/MONDAY MORNING...
OVERALL CONFIDENCE IN SNOWFALL AMOUNTS CONTINUES TO INCREASE FOR
AREAS NORTH OF THE US HWY 12 CORRIDOR, ALONG/NEAR THE MONTANA HWY
200 CORRIDOR, AND WEST OF THE US HWY 89 CORRIDOR ACROSS CENTRAL AND
PORTIONS OF NORTH CENTRAL MONTANA. HERE HI-RES GUIDANCE HAS BEEN
CONSISTENTLY SHOWING A NEARLY STATIONARY BAND OF MODERATE TO HEAVY
SNOW THROUGH MUCH OF THE NEXT 48 HOURS, WITH ADDITIONAL OROGRAPHIC
ENHANCEMENT FROM THE MID-SLOPES OF THE LITTLE BELTS AND ROCKY
MOUNTAIN FRONT OUT ONTO THE ADJACENT PLAINS ABOVE 3500 FEET.
AS HAS BEEN THE CASE FROM PREVIOUS FORECASTS SNOWFALL AMOUNTS WILL
VARY DRASTICALLY FROM GRASSY/ELEVATED SURFACES TO ROADWAYS/PAVED
SURFACES GIVEN RELATIVELY WARM GROUND TEMPERATURES AND THE EFFECTS
OF A HIGHER OCTOBER SUN ANGLE (DURING THE DAYLIGHT HOURS) AS
COMPARED TO THE HEART OF THE WINTER SEASON. WITH THAT BEING SAID,
SURFACE TEMPERATURES ALONG AND WEST OF THE I-15 CORRIDOR OVER THE
PLAINS OF CENTRAL AND NORTH CENTRAL MONTANA HAVE ALREADY FALLEN INTO
THE MID- TO UPPER 30S, WHICH WILL BE FAVORABLE FOR SNOWFALL TO
ACCUMULATE ON ROADWAYS IN THESE AREAS BY THE LATE AFTERNOON HOURS
TODAY AS SOLAR INSOLATION DECREASES. ALONG WITH THE IMPACTS TO
TRAVEL TO THE REGION THE HEAVY, WET NATURE OF THE SNOW HAS THE
POTENTIAL TO CAUSE CONSIDERABLE TREE DAMAGE WHERE FOLIAGE STILL
REMAINS. ADDITIONALLY, THIS HEAVY, WET SNOW ACCUMULATING ON
POWERLINES AND BREEZY NORTH WINDS COULD RESULT IN ISOLATED POWER
OUTAGES.
CURRENT SUITE OF WINTER WEATHER STATEMENT REMAIN VALID OUTSIDE OF
THE EAST GLACIER PARK REGION AND NORTHERN HIGH PLAINS WHERE THE
WINTER WEATHER ADVISORY HAS BEEN UPGRADED TO A WINTER STORM WARNING
DUE TO A TREND IN HIGHER SNOWFALL AMOUNTS. ADDITIONAL FOCUS WAS
GIVEN TO AREAS SOUTH AND EAST OF A BOZEMAN TO DILLON, AND THE HELENA
VALLEY FOR THE POTENTIAL NEED TO UPGRADE THE CURRENT ADVISORIES TO
WARNINGS. ULTIMATELY CONCERNS ABOUT SNOW LEVELS AND/OR MARGINAL
SURFACE TEMPERATURES STILL REMAIN AND CONFIDENCE IN WARNING LEVEL
AMOUNTS/IMPACTS REMAIN TOO LOW FOR AN UPGRADE.
LOW TEMPERATURES MONDAY NIGHT/TUESDAY MORNING...
CLEARING SKIES, LIGHT WINDS, AND A RELATIVELY FRESH SNOWPACK WILL
LIKELY RESULT IN THE COLDEST TEMPERATURES OF THE UPCOMING WEEK, WITH
A 25% CHANCE THAT LOWS FALL INTO THE TEENS ACROSS SOUTHWEST THROUGH
NORTH CENTRAL MONTANA. MODEL GUIDANCE IS NOTORIOUS FOR
UNDER-PERFORMING WITH RESPECT TO LOW TEMPERATURES GIVEN THE
AFOREMENTIONED CONDITIONS, SO IT IS REASONABLE TO BELIEVE THAT LOWS
COULD FALL AS LOW AS THE SINGLE DIGITS ABOVE ZERO AT SOME LOCATIONS
DURING THE TIMEFRAME. - MOLDAN
AVIATION
11/00Z TAF PERIOD
DURING THIS TAF PERIOD ACROSS ALL BUT THE KEKS, KBZN, AND KWYS
TERMINALS THERE WILL BE ALL SNOW. THIS SNOW WILL REDUCE
VISIBILITY TO AT LEAST IFR-LEVELS. AT THE KGTF TERMINAL VISIBILITY
WILL BE REDUCED TO LIFR-LEVELS FOR AT LEAST THE FIRST 6 HOURS OF
THIS TAF PERIOD. AT THE KBZN, KEKS, AND KWYS TERMINALS THERE WILL
BE PRIMARY RAIN DURING THE DURATION OF THIS TAF PERIOD WITH SNOW
AT TIMES. THIS WILL REDUCE VISIBILITY TO AT LEAST MVFR-LEVELS
DURING THIS TAF PERIOD. AT THE KBZN, KWYS, AND KEKS TERMINALS
BETWEEN NOW AND 11/06Z THERE IS A 20 - 30% CHANCE FOR
THUNDERSTORMS. ANY THUNDERSTORMS WILL BRING GUSTY, ERRATIC WINDS,
HEAVY DOWNPOURS, AND FREQUENT LIGHTNING. -IG
PRELIMINARY POINT TEMPS/POPS
GTF 27 32 24 35 / 100 100 100 60
CTB 23 31 22 35 / 100 100 90 40
HLN 28 32 26 38 / 100 100 100 50
BZN 29 34 25 38 / 100 100 100 50
WYS 30 43 23 41 / 90 100 100 70
DLN 28 30 23 37 / 90 100 100 40
HVR 27 36 24 38 / 100 100 100 80
LWT 29 34 25 35 / 100 100 100 80
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 VALLEY-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.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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