684
FXUS65 KTFX 120253
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
853 PM MDT TUE MAR 11 2025
KEY MESSAGES
- LIGHT SNOW OVER THE NORTHERN ROCKY MOUNTAIN FRONT TONIGHT.
- ABOVE AVERAGE TEMPERATURES THROUGH THURSDAY, WITH BREEZY
CONDITIONS AROUND AT TIMES.
- PACIFIC COLD FRONT BRINGS A MIX OF RAIN AND SNOW TO SOUTHWEST
AND CENTRAL MONTANA TERRAIN AND VICINITY THURSDAY INTO THURSDAY
NIGHT, WITH ACCUMULATING SNOW IN THE MADISONS, GALLATINS, AND
VICINITY.
- INCREASING CONFIDENCE IN INTENSE SNOW SHOWERS AT LOWER
ELEVATIONS ACROSS SOUTHWEST MONTANA THURSDAY AFTERNOON WITH
THE COLD FRONT.
- COOLER FOR FRIDAY AND THE WEEKEND, WITH AN ADDITIONAL BREEZY
PERIOD INCREASING IN LIKELIHOOD FOR SUNDAY AFTERNOON AND NIGHT.
UPDATE
UPDATED FORECAST IS OUT. JUST MINOR ADJUSTMENT TOWARDS CURRENT
TRENDS. TEMPERATURES/SKY GRIDS JUST ADJUSTED TOWARDS EVENING
TRENDS. LIGHT RAIN/SNOW IS DEVELOPING OVER THE NORTHERN ROCKIES,
AS MOIST SOUTHWEST FLOW DEVELOPS ALOFT. THE PRECIPITATION WILL BE
CONFINED TO MOSTLY AREAS RIGHT NEAR THE DIVIDE OVERNIGHT. SNOW
ACCUMULATIONS LOOK TO BE LIGHT, WITH AN INCH OR TWO POSSIBLE ON
MARIAS PASS. THUS A SPS WAS ISSUED TO HIGHLIGHT THE SNOWFALL
OVERNIGHT. OTHERWISE, THE REST OF THE FORECAST IS ON TRACK, WITH
THE NEXT CONCERN BEING THE BAND OF RAIN/SNOW AND ISOLATED
THUNDERSTORMS TO MOVE THROUGH SOUTHWEST MT ON THURSDAY. BRUSDA
DISCUSSION
/ISSUED 602 PM MDT TUE MAR 11 2025/
- METEOROLOGICAL OVERVIEW:
A LARGELY ZONAL FLOW ALOFT WILL BECOME INCREASINGLY SOUTHWESTERLY
WEDNESDAY AS THE NEXT LARGE SCALE TROUGH MOVES ONSHORE ACROSS THE
WESTERN CONUS. IN THE MEANTIME, DAYTIME MIXING HAS RESULTED IN A
BREEZY DAY ACROSS MUCH OF THE REGION, WITH WINDS FORECAST TO
DECREASE IN MAGNITUDE AROUND SUNSET. MOISTURE WITHIN THE ZONAL
FLOW WILL RESULT IN LIGHT PRECIPITATION AT TIMES, MOSTLY ALONG
THE CONTINENTAL DIVIDE NORTH OF LINCOLN OVER THE NEXT DAY OR SO.
AS THE FLOW ALOFT BECOMES MORE SOUTHWESTERLY WEDNESDAY AFTERNOON,
BREEZY WINDS WILL DEVELOP ACROSS SOUTHWEST MONTANA. FORECAST
SOUNDINGS AREN'T OVERLY OPTIMISTIC FOR WIDESPREAD HIGH WINDS,
THOUGH WIND PRONE AREAS LIKE NORRIS HILL DO LOOK TO HAVE A BETTER
OPPORTUNITY FOR STRONG WINDS/GUSTS INTO WEDNESDAY NIGHT.
MILD TEMPERATURES CONTINUE INTO THE DAY THURSDAY, THOUGH WILL
BEGIN TO TREND COOLER AS A PACIFIC COLD FRONT MOVES ACROSS THE
AREA IN THE AFTERNOON. PRECIPITATION INCREASES IN COVERAGE,
MOSTLY ALONG THE CONTINENTAL DIVIDE AND ACROSS SOUTHWEST MONTANA
THROUGH THE DAY. ACCUMULATING SNOWFALL WILL BE MOST FAVORED IN
THE MADISONS, GALLATINS, AND VICINITY THURSDAY INTO THURSDAY
NIGHT. INSTABILITY AHEAD OF AND ALONG THE COLD FRONT WILL BE
CAPABLE OF A FEW RUMBLES OF THUNDER, IN ADDITION TO AT LEAST A
LOW-END CHANCE FOR INTENSE SNOW SHOWERS AND PERHAPS SNOW SQUALLS
ACROSS SOUTHWEST MONTANA IN THE AFTERNOON AND EARLY EVENING
THURSDAY. FURTHER NORTH OVER THE PLAINS, THE MAIN IMPACTS FROM
THIS SYSTEM WILL BE FOR A TREND COOLER, WITH JUST A BRIEF
OPPORTUNITY FOR RAIN OR SNOW AS THE FRONT PROGRESSES THROUGH.
DISORGANIZED UPPER LEVEL TROUGHING WITH WEAK EMBEDDED WAVES WILL
STICK AROUND INTO SATURDAY, KEEPING LOW END OPPORTUNITIES FOR
PRECIPITATION AROUND, MOSTLY IN THE MOUNTAINS IN THE AFTERNOON
AND EARLY EVENING TIMEFRAME. BRIEF RIDGING MOVES IN FOR SUNDAY
BUT IS QUICKLY BROKEN DOWN HEADING INTO SUNDAY NIGHT BY AN UPPER
LEVEL TROUGH APPROACHING FROM THE PACIFIC NORTHWEST. SOUTHWEST
FLOW ALOFT IN ADVANCE OF THIS SYSTEM SUNDAY AFTERNOON AND NIGHT
LOOKS TO BRING ANOTHER BREEZY PERIOD TO SOUTHWEST MONTANA BEFORE
PRECIPITATION CHANCES INCREASE HEADING INTO MONDAY. THERE ARE
DISCREPANCIES IN TIMING AND NORTH-SOUTH POSITIONING OF THIS
SYSTEM HEADING INTO NEXT WEEK, WHICH LEADS TO A LOW CONFIDENCE
PRECIPITATION FORECAST. -AM
- FORECAST CONFIDENCE & SCENARIOS:
WIND WEDNESDAY IN SOUTHWEST MONTANA:
PROBABILISTIC GUIDANCE GIVES AROUND A 30 TO 50% CHANCE FOR A 58
MPH GUST IN THE DILLON TO TWIN BRIDGES AREA DURING THE AFTERNOON
HOURS WEDNESDAY. PROBABILITIES ARE SIMILAR FOR THE ENNIS AND
NORRIS HILL AREAS FROM THE AFTERNOON WEDNESDAY INTO WEDNESDAY
NIGHT. GIVEN THESE PROBABILITIES ARE JUST BARELY TOUCHING 50% IN
SPOTS, I WILL HOLD OFF ON A HIGH WIND WATCH FOR NOW, BUT THIS
WILL BE WORTH MONITORING OVER THE NEXT 24 HOURS FOR TRENDS.
INTENSE SNOW SHOWERS ACROSS SOUTHWEST MONTANA THURSDAY AFTERNOON:
HIGH RESOLUTION GUIDANCE THAT IS IN RANGE OF THURSDAY AFTERNOON
IS BEGINNING TO PAINT A PICTURE THAT THERE WILL BE A PERIOD OF AT
LEAST ISOLATED INTENSE SNOW SHOWERS NEAR A PACIFIC COLD FRONT
THAT WILL PROGRESS ACROSS THE REGION FROM WEST TO EAST.
TEMPERATURES AT THE SURFACE WILL BE MARGINAL FOR THE SNOW
HOWEVER, WHICH GIVES LOW CONFIDENCE FOR ACCUMULATIONS AT LOWER
ELEVATIONS. A MORE ORGANIZED AND SLIGHTLY COOLER SCENARIO WOULD
INCLUDE MORE ORGANIZED SNOW SHOWERS ALONG THE COLD FRONT THAT
HAVE THE ABILITY TO CONSOLIDATE INTO A SNOW SQUALL. TRENDS WILL
NEED TO BE MONITORED OVER THE NEXT 24-36 HOURS OR SO.
SOUTHWEST MONTANA MOUNTAIN SNOW THURSDAY INTO FRIDAY:
HIGH TERRAIN EAST OF I-15 IN SOUTHWEST MONTANA HAS BETWEEN A 50
AND 80% CHANCE FOR SNOW IN EXCESS OF 9 INCHES OVER THIS
TIMEFRAME. AT PASS LEVEL THESE PROBABILITIES LOWER SIGNIFICANTLY,
ONLY GETTING UP TO 20% OR SO OVER TARGHEE AND RAYNOLDS PASSES.
GIVEN THIS LOWER CONFIDENCE AT PASS LEVEL, I AM HOLDING OFF ON A
WINTER STORM WATCH AT THIS TIME.
SOUTHWEST MONTANA WIND LATE SUNDAY INTO SUNDAY NIGHT:
PROBABILISTIC GUIDANCE IS A BIT MORE OPTIMISTIC IN STRONG WINDS
OVER THIS TIMEFRAME, GIVING A 50-70% CHANCE FOR A 58 MPH GUST
OVER MANY LOWER ELEVATION LOCATIONS SOUTH OF THE US-12 CORRIDOR.
TIMING OF THE BEST WINDS ALOFT TWILL BE IMPORTANT IN DETERMINING
HOW WELL THE GUSTS WILL BE ABLE TO MIX TO THE SURFACE. -AM
AVIATION
12/00Z TAF PERIOD
A MODERATE WESTERLY FLOW ALOFT WILL CONTINUE MOUNTAIN WAVE
TURBULENCE ACROSS NORTH CENTRAL, CENTRAL, AND SOUTHWEST MONTANA
THROUGH AT LEAST 13/00Z, EVEN AS IT SHIFTS MORE SOUTHWESTERLY
AFTER 12/18Z. OTHERWISE, HIGH- AND MID-LEVEL VFR CLOUDINESS WILL
CONTINUE TO MOVE OVER THE AREA THROUGH THE PERIOD, POSSIBLY
CAUSING SOME MOUNTAIN TOP OBSCURING SNOW ALONG THE CONTINENTAL
DIVIDE NORTH OF KHLN. GUSTY SOUTHWESTERLY SURFACE WINDS WILL
DECREASE THROUGH 03Z, BUT THEY WILL INCREASE AGAIN AFTER 16Z,
ESPECIALLY THROUGH SOUTH-NORTH ORIENTED VALLEYS OF SOUTHWEST
MONTANA (INCLUDING KEKS).
-COULSTON
REFER TO WEATHER.GOV/ZLC FOR MORE DETAILED REGIONAL AVIATION
WEATHER AND HAZARD INFORMATION.
PRELIMINARY POINT TEMPS/POPS
GTF 38 61 40 57 / 10 10 10 30
CTB 32 54 31 51 / 10 10 0 10
HLN 34 58 36 52 / 20 10 10 50
BZN 29 55 32 49 / 10 0 0 60
WYS 19 45 30 41 / 0 10 70 80
DLN 30 54 34 47 / 0 0 20 70
HVR 32 57 34 60 / 10 10 0 10
LWT 31 55 36 55 / 10 10 0 40
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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