253
FXUS65 KTFX 130939
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
339 AM MDT THU MAR 13 2025
KEY MESSAGES
- LOCALLY HEAVY SNOW ACROSS SOME SOUTHWEST MONTANA MOUNTAIN RANGES
THROUGH TONIGHT.
- BRIEF BUT INTENSE SHOWERS WITH A PASSING COLD FRONT THIS
AFTERNOON AND EVENING WILL QUICKLY CHANGE TO SNOW THIS EVENING
IN THE GALLATIN AND MADISON VALLEYS.
- ACTIVE WEATHER PATTERN CONTINUES INTO NEXT WEEK WITH
TEMPERATURES REMAINING NEAR SEASONAL AVERAGES AND ADDITIONAL
PRECIPITATION CHANCES
DISCUSSION
- METEOROLOGICAL OVERVIEW:
AN UPPER LEVEL TROUGH DIGGING INLAND ALONG THE WEST COAST THIS
MORNING IS DIRECTING A PLUME OF PACIFIC MOISTURE NORTHWARD INTO SW
MT WHERE OROGRAPHICALLY GENERATED SNOW IS UNDERWAY ALONG THE ID BORDER
AND ADJACENT MOUNTAIN RANGES. THE UPPER TROUGH CONTINUES INLAND
TODAY WITH AN ASSOCIATED PACIFIC COLD FRONT MOVING EAST ACROSS THE
NORTHERN ROCKIES THIS AFTERNOON. RAIN AND MOUNTAIN SNOW SHOWERS WILL
SPREAD EAST OF THE CONTINENTAL DIVIDE BY EARLY THIS AFTERNOON,
BRINGING A SHIFT TO GUSTY WEST WINDS AND COOLER TEMPERATURES WITH
ITS PASSAGE TO MOST OF NORTH-CENTRAL AND CENTRAL MT BY EARLY THIS
EVENING.
ACROSS SW MT, HI-RESOLUTION MODEL GUIDANCE IS CONSISTENT IN SHOWING
A SOMEWHAT SLOWER PROGRESSION OF THE FRONT WITH INCREASED
FRONTOGENIC FORCING, GENERATING A BAND OF ENHANCED POST-FRONTAL
PRECIPITATION THIS EVENING ALONG AN AXIS ROUGHLY FROM MONIDA PASS
NORTHEAST THROUGH BOZEMAN PASS. COOLING AND LOWERING SNOW LEVELS
WILL LEAD TO A FAIRLY QUICK TRANSITION TO SNOW AT LOWER ELEVATIONS
IN THIS AREA, INCLUDING THE GALLATIN VALLEY AND OVER BOZEMAN PASS.
WINTER WEATHER ADVISORIES WERE EXPANDED TO INCLUDE MONIDA PASS, THE
MADISON AND GALLATIN VALLEYS AND BRIDGER RANGE WITH ACCUMULATIONS
AROUND 2 INCHES OR LESS IN THE VALLEYS WITH 2 TO 4 INCHES OVER THE
PASSES.
A FAIRLY ACTIVE WEATHER PATTERN CONTINUES INTO NEXT WEEK WITH A
SERIES OF PACIFIC WEATHER DISTURBANCES MOVING ACROSS THE REGION IN
THE WAKE OF THE INITIAL TROUGH PASSAGE TONIGHT. A SOMEWHAT UNSTABLE
NORTHWESTERLY FLOW IS IN PLACE FRIDAY AND SATURDAY WITH CHANCES FOR
SCATTERED PRECIPITATION MAINLY CONFINED TO THE MOUNTAINS. RIDGING
BRIEFLY DEVELOPS SUNDAY AS THE NEXT PLUME OF PACIFIC MOISTURE BEGINS
TO STREAM INTO THE REGION AHEAD A MORE ORGANIZED UPPER LEVEL TROUGH
TO MOVE THROUGH THE AREA EARLY NEXT WEEK.
- FORECAST CONFIDENCE & SCENARIOS:
THE GALLATIN VALLEY COULD SEE A LARGE SPREAD IN SNOW ACCUMULATION
WITH MINOR ACCUMULATION OF AN INCH OR LESS IN BELGRADE TO SEVERAL
INCHES FROM THE CITY OF BOZEMAN OVER BOZEMAN PASS AND HIGHER AMOUNTS
NEAR GALLATIN GATEWAY. WITH TEMPERATURES IN LOWER 50S TODAY, ROADS
WILL INITIALLY BE WARM AND IMPACTS TO THE THE COMMUTE EARLY THIS
EVENING MAY BE MORE FROM LOWER VISIBILITY, BUT THIS COULD BE
OVERCOME BY HIGHER SNOWFALL RATES WITH LATEST GUIDANCE GIVING THE
BOZEMAN AREA A 30% PROBABILITY OF RATES AS HIGH AS 1/2" PER HOUR AND
10% CHANCE OF RATES AS HIGH AS 1" PER HOUR THIS EVENING.
TEMPERATURES ALSO FALL TO THE 20S BY LATE THIS EVENING WHICH COULD
LEAD TO ADDITIONAL IMPACTS FROM WET ROAD SURFACES BECOMING ICY.
HOENISCH
AVIATION
13/06Z TAF PERIOD
VFR CONDITIONS WILL PREVAIL AT ALL TERMINALS EXCEPT FOR THE KEKS
TERMINAL DURING THE DURATION OF THIS TAF PERIOD. A COLD FRONT WILL
MOVE FROM WEST TO EAST DURING THIS TAF PERIOD REACHING KCTB AT
AROUND 13/17Z. IT WILL REACH KLWT AT AROUND 13/21Z. THIS COLD FRONT
WILL BRING SNOW AND RAIN TO THE KEKS, KBZN, AND KLWT TERMINALS. IT
HAS THE POTENTIAL TO BRING RAIN TO THE KHLN, KGTF, AND KHVR
TERMINALS. THE COLD FRONT WILL SHIFT WINDS FROM THE SOUTH AT ALL
TERMINALS TO BRIEFLY SOUTHWESTERLY AT AROUND FRONTAL PASSAGE. AFTER
FRONTAL PASSAGE WINDS WILL SHIFT TO NORTHWESTERLY. THE SNOW WILL
REDUCE VISIBILITY TO MVFR LEVELS AT THE KEKS TERMINAL BY THE END OF
THIS TAF PERIOD. THERE IS A L5% CHANCE FOR THUNDER AT THE KBZN AND
KEKS TERMINALS BETWEEN 13/18Z AND 13/06Z. ANY THUNDER WOULD CAUSE A
BRIEF RAPID REDUCTION IN VISIBILITY. AT THE KGTF AND KHVR TERMINALS
BETWEEN 13/22Z AND THE END OF THE TAF PERIOD THERE IS A 15% CHANCE
FOR RAIN. THERE WILL ALSO BE ISOLATED INSTANCES OF LOW-LEVEL WIND
SHEAR AND MOUNTAIN WAVE TURBULENCE ACROSS SOUTHWESTERN MONTANA
BETWEEN NOW AND 13/18Z. THERE WILL BE MOUNTAIN OBSCURATION AFTER
13/19Z ACROSS SOUTHWESTERN MONTANA. -IG
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 57 30 44 22 / 30 10 0 0
CTB 51 25 39 16 / 20 0 10 0
HLN 51 26 41 23 / 60 20 10 0
BZN 51 21 36 19 / 70 90 20 10
WYS 41 15 32 13 / 90 80 50 30
DLN 46 21 37 21 / 80 60 10 0
HVR 59 25 42 16 / 20 10 0 0
LWT 54 27 39 21 / 50 50 0 0
TFX WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 6 AM MDT
FRIDAY FOR BIG BELT, BRIDGER AND CASTLE MOUNTAINS-GALLATIN
VALLEY-MADISON RIVER VALLEY.
WINTER WEATHER ADVISORY UNTIL 6 AM MDT FRIDAY FOR GALLATIN AND
MADISON COUNTY MOUNTAINS AND CENTENNIAL MOUNTAINS-RUBY MOUNTAINS
AND SOUTHERN BEAVERHEAD MOUNTAINS.
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR NORTHWEST
BEAVERHEAD COUNTY.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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