465
FXUS65 KTFX 121145
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
545 AM MDT SUN OCT 12 2025
AVIATION SECTION UPDATED.
KEY MESSAGES
- SNOW DIMINISHES THIS AFTERNOON BEFORE ANOTHER ROUND OF SNOW
BRINGS WINTRY IMPACTS ALONG THE ROCKY MOUNTAIN FRONT AND THE
WESTERN PLAINS TONIGHT INTO MONDAY MORNING.
- TEMPERATURES WARM SLIGHTLY NEXT WEEK, BUT THERE WILL BE DAY TO
DAY OPPORTUNITIES FOR SCATTERED SHOWER ACTIVITY AND MOSTLY
MOUNTAIN SNOW, ESPECIALLY DURING THE SECOND HALF OF THE WEEK.
DISCUSSION
/ISSUED 406 AM MDT SUN OCT 12 2025/
- METEOROLOGICAL OVERVIEW:
THE TROUGH RESPONSIBLE FOR THIS MORNING'S SNOW WILL WEAKEN AND
SWING NORTHEASTWARD TODAY WHILE SOUTHWESTERLY FLOW ALOFT
REDEVELOPS IN RESPONSE TO A STRENGTHENING MID- LEVEL CIRCULATION
RETROGRADING SOUTHWESTWARD INTO THE PACIFIC NORTHWEST. SNOW ALONG
THE ROCKY MOUNTAIN FRONT, OVER THE SOUTHWESTERN MOUNTAINS, AND
OVER THE PLAINS WILL THIN OUT HEADING INTO THIS AFTERNOON.
THIS LULL IN ACTIVITY WILL BE BRIEF FOR NORTHERN AREAS DUE TO
NORTHEASTERLY UPSLOPE FLOW SETTING UP IN THE LOW LEVELS AND
COMBINING WITH WARM AIR ADVECTION/ISENTROPIC LIFT ALOFT. COLD AIR
WILL BECOME ESTABLISHED AT THE SURFACE TONIGHT INTO MONDAY WHILE
H700 TEMPERATURES GENERALLY REMAIN AROUND -10C OVER THE NORTHWEST
PORTIONS OF CENTRAL/NORTH-CENTRAL MT. THIS WILL RESULT IN MORE
WINTER IMPACTS AT LOWER ELEVATIONS THAN THE FIRST ROUND. AREAS
ALONG THE ROCKY MOUNTAIN FRONT AND THE PLAINS WEST OF I15,
INCLUDING THE CANYON AREA BETWEEN HELENA AND GREAT FALLS WILL BE
MOST SUSCEPTIBLE TO HIGHER END SNOW TOTALS TONIGHT INTO MONDAY
MORNING. SNOW DIMINISHES FOR MOST LOCATIONS BY MONDAY AFTERNOON,
THOUGH LIGHTER SNOWS MAY PERSIST THROUGH MONDAY NIGHT ALONG THE
ROCKY MOUNTAIN FRONT.
MOST ENSEMBLES FAVOR WEAK DIFLUENT FLOW ALOFT OVER THE NORTHERN
ROCKIES FOR THE FIRST HALF OF NEXT WEEK FOR SLIGHTLY WARMER, BUT
CONTINUED BELOW AVERAGE, TEMPERATURES AND DAY TO DAY LOWER GRADE
SHOWER AND MOUNTAIN SNOW ACTIVITY. THE PACIFIC NORTHWEST TROUGH
THEN MOVES INTO MONTANA LATER IN THE WEEK, THOUGH THE PRECISE
DETAILS OF THE TROUGH'S EVOLUTION IS UNCLEAR AT THIS TIME.
OVERALL, THERE'S AN EXPECTATION FOR INCREASED PRECIPITATION AND
MOUNTAIN SNOW FOR THE SECOND HALF OF THE WEEK WHILE TEMPERATURES
WARM SLIGHTLY. - RCG
- FORECAST CONFIDENCE & SCENARIOS:
SNOW TODAY THROUGH MONDAY...
OUTSIDE OF MOUNTAIN AREAS ALONG THE ROCKY MOUNTAIN FRONT AND IN
SOUTHWEST MT, SNOW HAS BEEN SLOW TO GET GOING DURING THE OVERNIGHT
HOURS. THERE'S STILL AN EXPECTATION FOR AT LEAST A PERIOD OF
LOWER ELEVATION SNOW OVER THE PLAINS WEST OF I15 THIS MORNING, BUT
OVERALL, IT'S NOW LOOKING LIKE THE MOST IMPACTFUL SNOW WILL BE
TONIGHT INTO MONDAY MORNING FOR LOCATIONS ALONG THE ROCKY MOUNTAIN
FRONT, THE CENTRAL ISLAND RANGES, AND THEIR NORTHERLY/EASTERLY
UPSLOPE FOOTHILLS/PLAINS. THE COMBINATION OF COLD LOW LEVEL
UPSLOPE FLOW AND WARM AIR ADVECTION ALOFT WILL BRING AN
OPPORTUNITY FOR THE MOST WIDESPREAD WINTER IMPACTS SO FAR THIS
FALL. NBM PROBABILITIES ARE SUPPORTING THIS SET UP WITH A 70 TO
90% CHANCE FOR SNOW AMOUNTS EXCEEDING 6 INCHES FOR LOCATION ALONG
AND WEST OF HIGHWAY 89 AND IN THE I15 CANYON AREA BETWEEN DEARBORN
AND WOLF CREEK. THERE ARE SIMILAR PROBABILITIES FOR SNOWFALL OVER
3 INCHES OR MORE FOR PORTIONS OF CASCADE AND JUDITH BASIN
COUNTIES. THE SOUTHERN PLAINS AND I15 CANYON ZONES WERE UPGRADED
TO A WINTER STORM WARNING FOR TONIGHT AND MONDAY MORNING WHILE
ADVISORIES WERE POSTED FOR SOME CENTRAL/NORTH-CENTRAL PLAINS ZONES
AND THE BOULDER AREA FARTHER SOUTHWEST IN JEFFERSON COUNTY.
IMPACTS WILL STILL BE GREATEST OVER THE HIGHER TERRAIN OF THE
ROCKY MOUNTAIN FRONT WHERE OUTDOOR RECREATION MAY BECOME DANGEROUS
WITH NEAR OR IMPASSIBLE FOREST ROADS. THERE WILL ALSO BE MORE
INSTANCES OF ICY/SNOWY ROADS TONIGHT AND MONDAY MORNING WITH
COLDER AIR IN PLACE, INCLUDING THE AFOREMENTIONED LOWER
ELEVATIONS. ISOLATED TO SCATTERED SNOW INDUCED POWER OUTAGES AND
OR TREE DAMAGE CAN ALSO BE EXPECTED. - RCG
AVIATION
12/12Z TAF PERIOD
SNOW/RAIN AND MVFR/IFR CONDITIONS ASSOCIATED WITH A PASSING
TROUGH AND COLD FRONT WILL CONTINUE THROUGH THE MORNING HOURS WITH
THE WORST CONDITIONS OVER CENTRAL AND NORTH-CENTRAL MT. THERE WILL
BE MODEST IMPROVEMENT BETWEEN 12/18 AND 13/00Z BEFORE WARM AIR
ADVECTION ALOFT COMBINED WITH LOW LEVEL NORTH TO NORTHEASTERLY
UPSLOPE FLOW BRINGS SNOW AND A RETURN OF MVFR/IFR CONDITIONS
BETWEEN 13/00 AND 13/18Z. ONCE AGAIN, THE CENTRAL AND NORTH-
CENTRAL MT TERMINALS WILL BE MOST IMPACTED BY DEGRADED FLIGHT
CATEGORIES. - RCG
PRELIMINARY POINT TEMPS/POPS
GTF 38 26 36 25 / 80 90 80 40
CTB 35 20 32 22 / 80 80 80 50
HLN 44 26 38 26 / 80 90 70 30
BZN 50 27 43 24 / 50 50 20 20
WYS 39 17 50 25 / 50 30 10 40
DLN 51 29 46 26 / 20 40 10 30
HVR 42 24 41 23 / 50 30 30 0
LWT 38 23 37 23 / 60 80 40 20
TFX WATCHES/WARNINGS/ADVISORIES
WINTER STORM WARNING UNTIL NOON MDT MONDAY FOR EAST GLACIER PARK
REGION-SOUTHERN ROCKY MOUNTAIN FRONT.
WINTER WEATHER ADVISORY UNTIL NOON MDT MONDAY FOR ELKHORN AND
BOULDER MOUNTAINS-LITTLE BELT AND HIGHWOOD MOUNTAINS-NORTHERN
HIGH PLAINS-UPPER BLACKFOOT AND MACDONALD PASS.
WINTER STORM WARNING FROM 6 PM THIS EVENING TO NOON MDT MONDAY
FOR GATES OF THE MOUNTAINS-SOUTHERN HIGH PLAINS.
WINTER WEATHER ADVISORY UNTIL 6 PM MDT THIS EVENING FOR GATES OF
THE MOUNTAINS-SOUTHERN HIGH PLAINS.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO NOON MDT
MONDAY FOR CASCADE COUNTY BELOW 5000FT-EASTERN PONDERA AND
EASTERN TETON-JUDITH BASIN COUNTY AND JUDITH GAP.
WINTER WEATHER ADVISORY UNTIL NOON MDT TODAY FOR GALLATIN AND
MADISON COUNTY MOUNTAINS AND CENTENNIAL MOUNTAINS.
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