929
FXUS65 KTFX 240425
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
925 PM MST THU JAN 23 2025
AVIATION SECTION UPDATED.
KEY MESSAGES
- IT WILL BE WINDY THIS AFTERNOON AND EVENING ACROSS NORTH-
CENTRAL AND CENTRAL MONTANA WITH THE STRONGEST WINDS ALONG THE
ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS ON THURSDAY.
- TONIGHT INTO EARLY FRIDAY MORNING A COLD FRONT WILL MOVE
THROUGH BRINGING WIDESPREAD SNOW AND COLDER TEMPERATURES FOR
THIS WEEKEND.
- EARLY NEXT WEEK TEMPERATURES WILL BEGIN TO WARM UP WITH DRY
CONDITIONS.
UPDATE
/ISSUED 818 PM MST THU JAN 23 2025/
818 PM MST UPDATE :
MAIN UPDATE THIS EVENING WAS TO EXPAND THE AREAL COVERAGE OF THE
WINTER WEATHER ADVISORY TO INCLUDE ALL AREAS OUTSIDE OF THE US HWY
2 CORRIDOR EAST OF SHELBY TO FORT BELKNAP IN NORTH CENTRAL MONTANA
AND AREAS WEST OF THE I-15 CORRIDOR FROM DIVIDE TO MONIDA PASS IN
SOUTHWEST MONTANA. SOME OF THE AREAS ADDED TO THE WINTER WEATHER
ADVISORY, MAINLY ALONG AND WEST OF THE I-15 CORRIDOR IN CENTRAL
AND NORTH CENTRAL MONTANA, WILL SEE SNOWFALL END SOONER THAN THE
CURRENT ENDTIME OF THE ADVISORY; BUT FOR SIMPLICITY SAKE AND IN
ORDER TO GET THE MESSAGE OUT AS SOON AS POSSIBLE I ATTACHED THEM
TO THE ORIGINAL PLAINS AREAS OF CENTRAL AND NORTH CENTRAL
MONTANA. LATEST HI-RES ENSEMBLE FORECAST (HREF) GUIDANCE THAT IS
COMING IN THIS EVENING SUPPORTS THE EXPANSION OF THE WINTER
WEATHER ADVISORY OVER CENTRAL AND NORTH CENTRAL MONTANA, WITH
WIDESPREAD ACCUMULATIONS OF 2-5" NOW EXPECTED THROUGH FRIDAY
MORNING HERE. FOR THE VALLEYS AND MOUNTAINS OF CENTRAL AND
SOUTHWEST MONTANA THAT WERE ADDED TO THE ADVISORY THE MAIN
REASONING FOR ADDING THESE AREAS WAS THE TIMING OF THE SNOW, WHICH
LOOKS TO INCONVENIENTLY MOVE THROUGH NEAR/DURING THE FRIDAY
MORNING COMMUTE. OTHERWISE THE REMAINDER OF THE FOREST REMAINS ON
TRACK, WITH ONLY MINOR ADJUSTMENTS MADE TO POPS. - MOLDAN
422 PM MST UPDATE :
THE HIGH WIND WARNING FOR THE EAST GLACIER PARK REGION, NORTHERN
HIGH PLAINS, AND EASTERN GLACIER, WESTERN TOOLE, AND CENTRAL PONDERA
COUNTIES HAS BEEN CANCELLED. WIND SPEEDS AND GUSTS HAVE FALLEN BELOW
WARNING CRITERIA LATE THIS AFTERNOON, BUT INFREQUENT WIND GUSTS IN
EXCESS OF 60 MPH ARE POSSIBLE ALONG AND WEST OF THE US HIGHWAY 89
CORRIDOR FROM DUPUYER NORTH TO THE CANADIAN BORDER. TRAVELERS ARE
STILL URGED TO EXERCISE CAUTION THROUGH THE EARLY EVENING HOURS DUE
TO THESE INFREQUENT GUSTS, ESPECIALLY IF OPERATING A HIGH-PROFILE
VEHICLE. - MOLDAN
DISCUSSION
/ISSUED 818 PM MST THU JAN 23 2025/
- METEOROLOGICAL OVERVIEW:
THIS AFTERNOON THERE IS AN UPPER-LEVEL RIDGE OVER NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA WHICH WILL BRIEFLY WARM UP
TEMPERATURES THIS AFTERNOON. DUE TO A STRONG SURFACE PRESSURE
GRADIENT THERE WILL BE STRONG WINDS THIS AFTERNOON THROUGH EARLY
THIS EVENING PRIMARILY ALONG THE ROCKY MOUNTAIN FRONT AND ADJACENT
PLAINS. DUE TO THE WINDS THERE WILL BE BLOWING SNOW THIS AFTERNOON
THROUGH THIS EVENING ACROSS NORTH-CENTRAL MONTANA WITH THE GREATEST
IMPACTS ALONG THE HIGHWAY 87/200 CORRIDOR. TONIGHT/EARLY FRIDAY
MORNING A COLD FRONT ASSOCIATED WITH AN UPPER-LEVEL TROUGH WILL MOVE
THROUGH. IT WILL BRING WIDESPREAD SNOW TO THE AREA AND COLDER
TEMPERATURES FOR FRIDAY AND SATURDAY. THERE WILL BE SNOWFALL RATES
IN EXCESS OF ONE HALF INCH PER HOUR WITH THE FRONTAL PASSAGE IN
NORTH-CENTRAL AND CENTRAL MONTANA LATE TONIGHT THROUGH EARLY FRIDAY
MORNING. LIGHT SNOW WILL CONTINUE ACROSS MUCH OF NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA DURING THE REST OF THE DAY ON
FRIDAY AFTER THE FRONTAL PASSAGE. ON FRIDAY AND SATURDAY THE UPPER-
LEVEL TROUGH REMAINS OVER NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN
MONTANA. LIGHT SNOW WILL LINGER IN CENTRAL MONTANA ON SATURDAY
MORNING. ON SUNDAY AN UPPER-LEVEL RIDGE BEGINS TO BUILD IN OVER
NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA. THE UPPER-LEVEL
RIDGE WILL REMAIN OVER THE AREA THROUGH AT LEAST NEXT THURSDAY. THIS
WILL GRADUALLY WARM UP TEMPERATURES AND DRY OUT NORTH-CENTRAL,
CENTRAL, AND SOUTHWESTERN MONTANA THROUGH AT LEAST NEXT THURSDAY.
EARLY NEXT WEEK IT WILL BE BREEZY AT TIMES TOO DUE TO A STRONG
SURFACE PRESSURE GRADIENT.
- FORECAST CONFIDENCE & SCENARIOS:
FOR THE SNOW TONIGHT THROUGH SATURDAY MORNING, THERE IS A 20 - 50%
CHANCE FOR 2 INCHES OF SNOW FOR LOWER-ELEVATION LOCATIONS ALONG THE
HIGHWAY 87/200 CORRIDOR SOUTH TO THE HELENA VALLEY. FOR THE REST OF
THE LOWER-ELEVATIONS OF NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN
MONTANA THERE IS A 20 - 50% CHANCE FOR AN INCH OF SNOW OR GREATER
FROM TONIGHT THROUGH SATURDAY MORNING. FOR THE MOUNTAINS OF CENTRAL
MONTANA THERE IS A 80% CHANCE FOR 6 INCHES OF SNOW OR GREATER FROM
TONIGHT THROUGH SATURDAY MORNING. FOR SNOWFALL RATES ASSOCIATED WITH
THE FRONTAL PASSAGE LATE TONIGHT THROUGH EARLY FRIDAY MORNING THERE
IS A 70% CHANCE OR GREATER FOR SNOWFALL RATES OF ONE HALF INCH PER
HOUR ACROSS MUCH OF NORTH-CENTRAL AND CENTRAL MONTANA. FROM THE
BEARS PAW MOUNTAINS SOUTHWEST TO THE LITTLE BELT MOUNTAINS THERE IS
A 70% CHANCE FOR SNOWFALL RATES OF ONE INCH PER HOUR LATE TONIGHT
INTO EARLY FRIDAY MORNING. AS A RESULT ACROSS MUCH OF NORTH-CENTRAL
AND CENTRAL MONTANA WINTER WEATHER ADVISORIES REMAIN IN EFFECT FROM
TONIGHT THROUGH FRIDAY NIGHT. THE WINTER WEATHER ADVISORY FOR THE
LITTLE BELT AND HIGHWOOD MOUNTAINS WAS UPGRADED TO A WINTER STORM
WARNING. SEE THE WATCHES/WARNINGS/ADVISORIES SECTION BELOW FOR
DETAILS.
FOR THE REST OF THE FORECAST PERIOD THERE IS HIGH CONFIDENCE THAT
NORTH-CENTRAL, CENTRAL, AND SOUTHWESTERN MONTANA WILL BE UNDER AN
UPPER-LEVEL RIDGE THROUGH AT LEAST NEXT THURSDAY. -IG
AVIATION
24/06Z TAF PERIOD
WINDS HAVE SHIFTED TO NORTH AND NORTHWEST AT KCTB AND KHVR WITH
THE PASSAGE OF COLD FRONT WITH THE FRONT CONTINUING SOUTH THROUGH
CENTRAL MT EARLY IN THE OVERNIGHT PERIOD AND THROUGH SW MT EARLY
FRIDAY MORNING. SNOW AND MVFR CONDITIONS DEVELOP AT MOST TERMINALS
FOLLOWING THE FRONTAL PASSAGE WITH A BRIEF PERIOD OF IFR TO LIFR
CONDITIONS POSSIBLE IN EMBEDDED BANDS WITH HEAVIER SNOWFALL RATES.
SNOW ENDS FROM NORTH TO SOUTH ON FRIDAY WITH IMPROVING CONDITIONS
BUT LIKELY SOME LINGERING LOWER TO MID LEVEL CLOUDS AND MOUNTAIN
OBSCURATION. NORTHERLY SURFACE WINDS ALSO INCREASE FRIDAY
AFTERNOON AND MAY BRING SOME BLOWING SNOW TO KHVR AND KLWT.
HOENISCH
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 20 28 13 25 / 100 60 40 0
CTB 15 26 7 24 / 100 30 10 0
HLN 17 28 10 23 / 100 90 30 0
BZN 11 26 2 19 / 50 100 10 0
WYS -3 21 -12 17 / 30 70 0 0
DLN 11 24 0 17 / 20 40 0 0
HVR 16 27 9 24 / 80 10 0 0
LWT 18 24 9 20 / 100 50 30 0
TFX WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL 11 PM MST FRIDAY FOR BEARS PAW
MOUNTAINS AND SOUTHERN BLAINE-CASCADE COUNTY BELOW 5000FT-
EASTERN GLACIER, WESTERN TOOLE, AND CENTRAL PONDERA-EASTERN
PONDERA AND EASTERN TETON-FERGUS COUNTY BELOW 4500FT-JUDITH
BASIN COUNTY AND JUDITH GAP-NORTHERN HIGH PLAINS-SOUTHERN HIGH
PLAINS-WESTERN AND CENTRAL CHOUTEAU COUNTY.
WINTER STORM WARNING UNTIL 11 PM MST FRIDAY FOR LITTLE BELT AND
HIGHWOOD MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL 11 PM MST FRIDAY FOR BIG BELT,
BRIDGER AND CASTLE MOUNTAINS-EAST GLACIER PARK REGION-ELKHORN
AND BOULDER MOUNTAINS-GATES OF THE MOUNTAINS-SNOWY AND JUDITH
MOUNTAINS-SOUTHERN ROCKY MOUNTAIN FRONT-UPPER BLACKFOOT AND
MACDONALD PASS.
WINTER WEATHER ADVISORY UNTIL NOON MST FRIDAY FOR CANYON FERRY
AREA-GALLATIN VALLEY-GALLATIN AND MADISON COUNTY MOUNTAINS AND
CENTENNIAL MOUNTAINS-HELENA VALLEY-MADISON RIVER VALLEY-MEAGHER
COUNTY VALLEYS-MISSOURI HEADWATERS.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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