556
FXUS65 KTFX 122350
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
550 PM MDT WED MAR 12 2025
AVIATION SECTION UPDATED.
KEY MESSAGES
- SNOW, HEAVY AT TIMES, EXPECTED ACROSS SOUTHWESTERN MONTANA ON
THURSDAY.
- NEXT NOTABLE SYSTEM ARRIVES SUNDAY AND MONDAY, BRINGING GUSTY
WINDS AND WIDESPREAD SNOWFALL TO THE AREA.
- QUIETER WEATHER EXPECTED FOR MID NEXT WEEK AS HIGH PRESSURE
SETS UP ACROSS THE AREA.
DISCUSSION
/ISSUED 212 PM MDT WED MAR 12 2025/
- METEOROLOGICAL OVERVIEW:
AN UPPER LEVEL RIDGE CURRENTLY SITUATED OVER THE NORTHERN ROCKIES
TODAY WILL GRADUALLY SHIFT EASTWARD AND GIVE WAY TO A SHORTWAVE
TROUGH THAT WILL PUSH ITS WAY THROUGH THE AREA ON THURSDAY. AS
THIS TROUGH PUSHES THROUGH, SOME HIGHER ELEVATION AREAS OF
SOUTHWESTERN MONTANA WILL SEE PERIODS OF MODERATE TO HEAVY
SNOWFALL, WITH SOME BURSTS OF MODERATE TO HEAVY SNOW POSSIBLE AT
THE LOWER ELEVATIONS NEAR AND SOUTH OF I-90. AFTER THIS SYSTEM
CLEARS THE AREA ON FRIDAY, STRONG WESTERLY FLOW WILL REMAIN ACROSS
THE AREA, WHICH WILL RESULT IN BREEZY AND CLOUDY CONDITIONS
ACROSS THE AREA WITH A FEW AREAS OF MOUNTAIN SNOW SHOWERS. ANOTHER
UPPER LEVEL TROUGH WILL PUSH THROUGH THE AREA SUNDAY AND MONDAY,
BRINGING ANOTHER ROUND OF INCREASED WIND AND WIDESPREAD SNOWFALL
TO NORTH CENTRAL AND SOUTHWESTERN MONTANA BEFORE UPPER LEVEL
RIDGING RETURNS FOR MID WEEK.
- FORECAST CONFIDENCE & SCENARIOS:
THURSDAY: AS THE UPPER LEVEL TROUGH PUSHES THROUGH THE AREA,
CONVECTIVE SNOW SHOWERS WILL DEVELOP ACROSS SOUTHWESTERN MONTANA.
GIVEN THE CONVECTIVE NATURE OF THESE SNOW SHOWERS, SNOWFALL
AMOUNTS WILL BE HIGHLY VARIABLE AND HARD TO PIN DOWN, BUT WE CAN
GET SOME IDEAS FOR THE IMPACTS WE EXPECT. FOR STARTERS, CONVECTIVE
SNOW SHOWERS LIKE THESE ARE NOTORIOUS FOR PRODUCING BRIEF BURSTS
OF HEAVIER SNOWFALL THAT CAN RAPIDLY REDUCE VISIBILITY AND QUICKLY
CHANGE ROAD CONDITIONS, AND WITH THE SETUP TOMORROW I EXPECT WE
WILL SEE THIS PLAY OUT ACROSS AREAS ALONG AND SOUTH OF I-90.
SNOWFALL ACCUMULATIONS ACROSS THE HIGHER ELEVATIONS WILL GENERALLY
REACH 6-8 INCHES OR SO, BUT AREAS THAT SEE TRAINING SNOW SHOWERS
COULD SEE LOCALLY HIGHER AMOUNTS, WITH THE POSSIBILITY OF SOME
AREAS SEEING OVER A FOOT, PARTICULARLY THE PEAKS AND HIGHER
PASSES.
SUNDAY THROUGH TUESDAY: OUR NEXT WEATHER SYSTEM WILL ARRIVE EARLY
NEXT WEEK, BRINGING GUSTY WINDS TO SOUTHWESTERN MONTANA, WHERE
THE NBM HAS BEEN GIVING A WIDESPREAD 50% CHANCE OF 55 MPH WIND
GUSTS AT SOME POINT ON SUNDAY. WHILE THIS DOES MEET THE TYPICAL
CRITERIA FOR A HIGH WIND WATCH, WE ARE A BIT FAR OUT FOR THAT TO
BE ISSUED, THOUGH WE WILL NEED TO WATCH THIS CLOSELY OVER THE NEXT
24 HOURS TO SEE IF THESE PROBABILITIES CONTINUE TO HOLD FAST.
SNOWFALL WILL BE THE OTHER PART OF THIS SYSTEM, WITH CURRENT
OPERATIONAL AND ENSEMBLE BLENDS SHOWING WIDESPREAD SNOWFALL WITH
SOME LOWER ELEVATION RAINFALL SPREADING OVER THE AREA SUNDAY NIGHT
AND MONDAY. THERE DOES REMAIN SOME UNCERTAINTY WITH HOW FAR NORTH
THE SNOWFALL WILL REACH, HOWEVER, AS MOST MODELS HAVE TENDED TO
KEEP THE PRECIPITATION OVER THE MOUNTAIN VALLEY REGION OF
SOUTHWESTERN MONTANA AND ALONG THE CONTINENTAL DIVIDE IN NORTHERN
MONTANA. HOWEVER, THERE IS AROUND 30-40% OF THE ENSEMBLE SPACE
THAT BRINGS THE PRECIPITATION A BIT FURTHER NORTH, WHICH COULD
BRING A LIGHT COATING OF SNOWFALL TO THE PLAINS. LUDWIG
AVIATION
13/00Z TAF PERIOD
MAIN CONCERN OVER THE NEXT DAY OR SO WILL BE SNOW ALONG THE DIVIDE
TONIGHT, THEN A BAND OF RAIN/SNOW/ISOLATED THUNDERSTORMS MOVING
EASTWARD ACROSS SOUTHWEST MT ON THURSDAY AFTERNOON. THE SNOW
SHOWERS TONIGHT SHOULD MAINLY AFFECT MOUNTAIN AREAS ALONG THE
DIVIDE, WITH SOME MOUNTAIN OBSCURATIONS. ON THURSDAY, A PACIFIC
COLD FRONT WILL MOVE FROM WEST TO EAST ACROSS THE CWA. A BAND OF
RAIN/SNOW/ISOLATED THUNDERSTORMS/GUSTY WINDS WILL ACCOMPANY THE
FRONTAL PASSAGE. MOST OF THE ISOLATED THUNDERSTORMS SHOULD BE
SOUTH OF A LINE FROM HELENA TO WHITE SULPHUR SPRINGS, AND FROM
ABOUT 21Z THU TO 03Z ON FRI. SNOW SHOWERS COULD BE HEAVY FOR A
SHORT TIME, BUT CONFIDENCE IS NOT HIGH ENOUGH TO PUT IN HEAVY SNOW
AT THE TERMINAL SITES AT THIS TIME. OVERALL, MOST OF THE SNOW
SHOWERS SHOULD DIMINISH BY 12Z FRI. BRUSDA
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 37 56 31 44 / 10 20 10 10
CTB 29 52 23 39 / 0 10 0 10
HLN 36 52 26 41 / 10 50 30 10
BZN 32 51 21 37 / 0 70 80 20
WYS 28 41 16 31 / 60 70 90 60
DLN 32 47 21 37 / 10 60 50 10
HVR 29 59 24 42 / 0 20 20 10
LWT 34 55 26 38 / 10 60 60 10
TFX WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY FROM 6 AM THURSDAY TO 6 AM MDT FRIDAY
FOR GALLATIN AND MADISON COUNTY MOUNTAINS AND CENTENNIAL
MOUNTAINS.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT MDT
THURSDAY NIGHT FOR NORTHWEST BEAVERHEAD COUNTY.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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