104
FXUS65 KTFX 241858
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1158 AM MST FRI JAN 24 2025
KEY MESSAGES
- LIGHT SNOW CONTINUES TO MORNING OVER MUCH OF THE CWA.
- SNOWFALL GRADUALLY ENDS THIS AFTERNOON AND OVERNIGHT TONIGHT.
- GENERALLY BELOW NORMAL TEMPERATURES THROUGH THE WEEKEND,
BEFORE A SLOW WARMING TREND BEGINS NEXT WEEK.
- GENERALLY DRY CONDITIONS EXPECTED MUCH OF NEXT WEEK.
UPDATE
1155AM UPDATE: THE WINTER WEATHER ADVISORY IN THE CENTRAL AND
SOUTHWEST MONTANA VALLEYS WAS EXTENDED THROUGH MID-AFTERNOON.
ALTHOUGH SNOW IS ENDING IN NORTHERN AREAS IN THIS ADVISORY,
ADDITIONAL LIGHT SNOW STILL LOOKS TO POSE IMPACTS TO TRAVEL.
FURTHER NORTH ACROSS THE PLAINS, A LARGE SECTION OF THE WINTER
WEATHER ADVISORY WAS CANCELED EARLY. ADDITIONAL SCATTERED SNOW
SHOWERS WILL BE POSSIBLE ACROSS THESE AREAS, BUT WIDESPREAD
IMPACTS ARE NOT EXPECTED. POCKETS OF BLOWING SNOW WILL BE POSSIBLE
THIS AFTERNOON ACROSS JUDITH BASIN AND FERGUS COUNTIES AND
VICINITY AS NORTHWESTERLY SURFACE WINDS INCREASE. NO OTHER CHANGES
WERE MADE AT THIS TIME. -AM
9 AM UPDATE: THE BAND OF MODERATE TO AT TIMES HEAVY SNOW
CONTINUES TO PROGRESS SOUTHWARD ACROSS CENTRAL AND INTO SOUTHWEST
MONTANA THIS MORNING. LATEST MESOANALYSIS SHOWS A DGZ DEPTH ON THE
ORDER OF 700 TO 800 METERS. COMBINE THIS WITH FORECAST SOUNDINGS
SHOWING FORCING MAXIMIZED WITHIN THE DGZ, AND IT IS NO SURPRISE
THAT SNOWFALL RATES ARE APPROACHING OR AT LEAST BRIEFLY EXCEEDING
AN INCH PER HOUR WITHIN THE HEAVIEST BANDS. THIS BEST FORCING
SLOWLY SLIDES SOUTHWARD THROUGH THE REMAINDER OF THE MORNING AND
PERHAPS LINGERS INTO EARLY AFTERNOON NEAR THE I-90 CORRIDOR.
TRENDS WILL NEED TO BE CLOSELY MONITORED OVER THE NEXT COUPLE
HOURS FOR THE POTENTIAL EXTENSION OF THE WINTER WEATHER ADVISORY
THROUGH MID- AFTERNOON. AS FORCING DIMINISHES ACROSS CENTRAL AND
NORTH-CENTRAL MONTANA, WIDESPREAD SNOW WILL BECOME MORE CONFINED
TO NORTHERLY AND NORTHWESTERLY UPSLOPE AREAS, INCLUDING THE LITTLE
BELTS, WHERE A WINTER STORM WARNING REMAINS IN EFFECT.
AT LEAST PARTIAL CLEARING IS PROGRESSING SOUTHWARD ACROSS THE
CANADIAN BORDER THIS MORNING. THE SUNSHINE FROM THIS, ALONG WITH
QUITE COOL TEMPERATURES ALOFT LOOK TO RESULT IN AT LEAST A FEW
HOUR PERIOD OF SNOW SHOWERS ACROSS THE PLAINS OF NORTH-CENTRAL
MONTANA THIS AFTERNOON. HOW WIDESPREAD THESE SNOW SHOWERS WILL BE
IS QUESTIONABLE AT THIS TIME, BUT I DID INCLUDE A LOW-END MENTION
OF IT WITH THE UPDATE THIS MORNING.
SNOW IN THE UPSLOPE AREAS SLOWLY DIMINISHES LATE EVENING AND
OVERNIGHT, WITH JUST A FEW FLURRIES LINGERING INTO SATURDAY
MORNING. THE FORECAST WAS FINE TUNED WITH LATEST GUIDANCE FOR THE
DAY TODAY, OTHERWISE NO CHANGES WERE MADE AT THIS TIME. -AM
DISCUSSION
/ISSUED 1022 AM MST FRI JAN 24 2025/
- METEOROLOGICAL OVERVIEW:
AN UPPER LEVEL DISTURBANCE CONTINUES TO MOVE SLOWLY SOUTHWARD
THROUGH THE CWA THIS MORNING. SNOWFALL HAS BEEN LIGHT MOST OF THE
NIGHT, WITH SNOW RATIOS INCREASING OVER THE PAST FEW HOURS THOUGH.
EXPECT THE SNOW TO GRADUALLY BEGIN TO END STARTING LATE THIS
MORNING AND WITH THE SNOW ENDING OVERNIGHT IN THE LITTLE BELT
MOUNTAINS. THE ONLY ADJUSTMENT TO THE WINTER WEATHER ADVISORY WAS
TO END THE BROWNING/CUT BANK AREA AT 18Z. OTHERWISE, THE END
TIMES REMAIN THE SAME AS PREVIOUS FORECAST FOR THE OTHER ZONES.
QUIET WEATHER CONDITIONS ARE THEN EXPECTED FOR THE NEXT SEVERAL
DAYS. WITH SKIES CLEARING OUT ON SUNDAY MORNING, IT COULD BE
QUITE COLD IN THE VALLEYS OF THE SOUTHWEST MT. THUS A COLD
ADVISORY WAS ISSUED FOR THE WEST YELLOWSTONE AREA FOR SUNDAY
MORNING. OTHERWISE, THE NEXT CHANCE FOR PRECIPITATION IS REALLY
NOT EXPECTED UNTIL ABOUT NEXT FRIDAY AT THIS TIME.
- FORECAST CONFIDENCE & SCENARIOS:
THE MAIN CONCERN WILL BE THE SNOW ACCUMULATIONS THIS MORNING.
WITH VISIBILITY NEAR ONE MILE, SNOWFALL RATES ARE NEAR 1 INCH PER
HOUR BECAUSE OF THE SNOW RATIO. OVERALL THE PREVIOUS SNOWFALL
FORECAST IS ON TRACK, WITH SNOW ACCUMULATIONS OF 1 TO 3 INCHES
COMMON AT LOWER ELEVATIONS AND 3 TO 6 INCHES IN THE MOUNTAINS.
SNOWFALL AMOUNTS AROUND 9 TO 10 INCHES WILL BE POSSIBLE IN THE
KINGS HILL AND BIG SNOWY AREAS.
IF SNOWFALL RATES OF 1 INCH PER HOUR CONTINUE FOR 3 TO 4 HOURS,
OVERALL STORM TOTAL SNOWFALL AMOUNTS WILL BE A BIT HIGHER THAN
CURRENTLY FORECAST. THERE IS A SMALL POTENTIAL FOR THESE HIGHER
SNOWFALL AMOUNTS IN THE GREAT FALLS AND CASCADE AREAS, WHERE
SNOWFALL RATES ARE NEAR 1 INCH PER HOUR CURRENTLY. BRUSDA
AVIATION
24/18Z TAF PERIOD
THE PRIMARY CONCERN THIS TAF PERIOD WILL BE FOR BANDS OF SNOW
CONTINUING SOUTHWARD ACROSS CENTRAL AND SOUTHWEST MONTANA THIS
AFTERNOON. IFR CONDITIONS ARE EXPECTED UNDER THESE BANDS, WITH
LIFR AT TIMES DUE TO VIS REDUCTION. FURTHER NORTH ACROSS THE
PLAINS, SNOW WILL TRANSITION TO BE MORE SHOWERY AND SCATTERED IN
NATURE THROUGH THE AFTERNOON. BREEZY NORTHWEST WINDS ACROSS THE
EASTERN PLAINS MAY BRIEFLY RESULT IN INSTANCES OF BLOWING SNOW,
BUT CONFIDENCE IS LOW AT THIS TIME. ALTHOUGH SNOW ACROSS THE
REGION WILL BE ON A DIMINISHING TREND THROUGH EVENING, LINGERING
LOW CLOUDS WILL RESULT IN MVFR CONDITIONS AT TIMES, WITH MOUNTAINS
REMAINING OBSCURED THROUGH SATURDAY MORNING. -AM
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 29 12 24 8 / 90 20 0 0
CTB 26 8 24 11 / 20 30 0 0
HLN 28 9 21 -1 / 100 30 0 0
BZN 25 0 17 -9 / 100 10 0 0
WYS 21 -14 17 -27 / 90 10 0 0
DLN 24 1 16 -6 / 50 20 0 0
HVR 28 9 23 9 / 20 20 0 0
LWT 24 7 19 3 / 60 60 0 0
TFX WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR BEARS
PAW MOUNTAINS AND SOUTHERN BLAINE-BIG BELT, BRIDGER AND CASTLE
MOUNTAINS-CASCADE COUNTY BELOW 5000FT-ELKHORN AND BOULDER
MOUNTAINS-FERGUS COUNTY BELOW 4500FT-GATES OF THE MOUNTAINS-
JUDITH BASIN COUNTY AND JUDITH GAP-SNOWY AND JUDITH MOUNTAINS-
SOUTHERN ROCKY MOUNTAIN FRONT-UPPER BLACKFOOT AND MACDONALD PASS.
WINTER STORM WARNING UNTIL 11 PM MST THIS EVENING FOR LITTLE
BELT AND HIGHWOOD MOUNTAINS.
COLD WEATHER ADVISORY FROM MIDNIGHT SATURDAY NIGHT TO 11 AM MST
SUNDAY FOR GALLATIN AND MADISON COUNTY MOUNTAINS AND CENTENNIAL
MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL 3 PM MST THIS AFTERNOON 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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