126
FXUS65 KTFX 291758
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1158 AM MDT SAT AUG 29 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS, WITH HIGHER
RAINFALL AMOUNTS THROUGH THE WEEKEND, WITH THE POTENTIAL FOR
SOME MINOR MOUNTAIN SNOW AT RIDGE TOPS ON SUNDAY.
- BREEZY AND GUSTY WINDS ON SUNDAY, ESPECIALLY ALONG THE ROCKY
MOUNTAIN FRONT AND ACROSS THE MONTANA HWY 200 CORRIDOR.
- WELL BELOW NORMAL TEMPERATURES ON SUNDAY.
DISCUSSION
/ISSUED 520 AM MDT SAT AUG 29 2026/
- METEOROLOGICAL OVERVIEW:
AN ACTIVE AND UNSETTLED PATTERN WILL BRING DAILY CHANCES FOR
PRECIPITATION, WITH THE EXCEPTION OF MONDAY, TO MOST LOCATIONS OVER
THE COURSE OF THE NEXT WEEK. OVER THE COURSE OF THE NEXT WEEK
TEMPERATURES WILL FLUCTUATE BETWEEN NEAR TO BELOW NORMAL, WITH THE
COLDEST DAY OF THE UPCOMING WEEK ARRIVING ON SUNDAY AS A LARGE UPPER
LEVEL TROUGH MOVES OVERHEAD. AS THIS UPPER LEVEL TROUGH AND CLOSED
LOW MOVES OVERHEAD ON SUNDAY SNOW LEVELS WILL FALL TO AS LOW AS
7000FT ACROSS THE GLACIER NATIONAL PARK REGION, WHICH COULD LEAD TO
SOME LIGHT SNOW ACCUMULATIONS FOR THE PEAKS OF THE PARK.
ADDITIONALLY ON SUNDAY, INCREASING CROSS BARRIER FLOW WILL
CONTRIBUTE TO BREEZY AND GUSTY WEST WINDS FOR MOST LOCATIONS ACROSS
SOUTHWEST THROUGH NORTH CENTRAL MONTANA, ESPECIALLY OVER THE PLAINS
OF CENTRAL AND NORTH CENTRAL MONTANA. PRIOR TO THE TROUGH MOVING
OVERHEAD ON SUNDAY MOIST AND UNSTABLE SOUTHWEST FLOW ALOFT COMBINED
WITH SUFFICIENT SHEAR WILL HELP TO SUPPORT THE POTENTIAL FOR A FEW
STRONG THUNDERSTORMS ACROSS SOUTHWEST MONTANA TODAY, GENERALLY ALONG
AND SOUTH OF THE I-90 CORRIDOR. THE MAIN THREAT FROM ANY STORM THAT
DOES BECOME STRONG OR SEVERE WILL BE STRONG WINDS, ESPECIALLY ALONG
THE IMMEDIATE IDAHO AND WYOMING BORDERS.
BEYOND THE WEEKEND BROAD TROUGHING CONTINUES TO BE SUPPORTED ACROSS
THE WESTERN CONUS, ESPECIALLY FROM TUESDAY THROUGH NEXT SATURDAY,
WITH MOIST SOUTHWEST FLOW OVER THE NORTHERN ROCKIES HELPING TO
SUPPORT THE AFOREMENTIONED DAILY CHANCES FOR SHOWERS AND
THUNDERSTORMS. - MOLDAN
- FORECAST CONFIDENCE & SCENARIOS:
GUSTY WINDS ON SUNDAY...
ECMWF EFIS CONTINUE TO SUPPORT THE POTENTIAL FOR A CLIMATOLOGICALLY
UNUSUAL, WITH RESPECT TO THE FINAL WEEK OF AUGUST, WIND EVENT ALONG
THE ROCKY MOUNTAIN AND ACROSS THE MONTANA HWY 200 CORRIDOR ON SUNDAY
AS CROSS BARRIER FLOW INCREASES TO BETWEEN 35-45KTS; WHICH IS
GENERALLY 1 TO 1.5 STANDARD DEVIATIONS ABOVE NORMAL PER NAEFS
ANALYSIS. BUFKIT SOUNDINGS ACROSS THE AFOREMENTIONED AREAS DEPICT
DEEP MIXING TO BETWEEN 4-6KFT DURING THE AFTERNOON HOURS ON SUNDAY,
WHICH WILL COINCIDE WITH THE PASSAGE OFF THE UPPER LEVEL TROUGH AXIS
AND ASSOCIATED SUBSIDENCE. THIS GIVES INCREASED CONFIDENCE THAT A
PERIOD OF STRONG AND GUSTY WINDS WILL OCCUR, ESPECIALLY ACROSS WIND
PRONE AREAS OF CENTRAL AND NORTH CENTRAL MONTANA, DURING THE
AFTERNOON AND INTO THE EARLY EVENING HOURS. WHILE HIGH WIND
HIGHLIGHTS DO NOT LOOK NECESSARY THOSE TRAVELING ALONG THE ROCKY
MOUNTAIN FRONT IN HIGH PROFILE VEHICLES SHOULD BE PREPARED FOR
PERIODS OF STRONG CROSS WINDS.
LISTED BELOW ARE THE NBM5.0 PROBABILITIES FOR WIND GUSTS TO EXCEED
35, 45, AND 55 MPH FOR SELECT LOCATIONS ACROSS NORTH CENTRAL,
CENTRAL, AND SOUTHWEST MONTANA.
SUNDAY'S WIND GUSTS PROBABILITIES
LOCATION > 35 MPH | > 45 MPH | > 55 MPH
BABB 100% | 60% | 10%
EAST GLACIER 100% | 70% | 5%
BROWNING 100% | 70% | 10%
CUT BANK 100% | 75% | 10%
SHELBY 90% | 20% | <5%
HAVRE 90% | 40% | <5%
HEART BUTTE 100% | 85% | 15%
CHOTEAU 80% | 15% | <5%
AUGUSTA 85% | 20% | <5%
GREAT FALLS 90% | 55% | 5%
LEWISTOWN 65% | 10% | 0%
HELENA 85% | 25% | <5%
BOZEMAN 55% | 20% | <5%
DILLON 75% | 10% | 0%
ENNIS 60% | 10% | 0%
WEST YELLOWSTONE 85% | 10% | 0%
WEEKEND PRECIPITATION...
MULTIPLE ROUNDS OF SHOWERS AND ISOLATED THUNDERSTORMS WILL BRING
BENEFICIAL RAINFALL TO MOST OF SOUTHWEST THROUGH NORTH CENTRAL
MONTANA, WITH THE EXCEPTION OF THE THE EAST GLACIER PARK REGION AND
NORTHERN HIGH PLAINS ZONES WHERE THE PROBABILITY FOR WETTING (0.1")
RAINFALL IS LARGELY LESS THAN A 50% CHANCE, OVER THE NEXT 48 HOURS
(12Z SATURDAY THROUGH 12Z MONDAY). OUTSIDE OF THESE AREAS MOST OTHER
LOCATIONS HAVE A 70%+ CHANCE OF A WETTING RAINFALL THROUGH SUNDAY
NIGHT, WITH A CORRIDOR OF 40-80% CHANCE PROBABILITIES FOR A 0.5" OF
RAINFALL FOR AREAS ALONG AND EAST OF A LEWISTOWN, TO GREAT FALLS, TO
TOWNSEND, TO BOZEMAN, TO ENNIS, TO MONIDA PASS LINE.
LISTED BELOW ARE THE NBM5.0 PROBABILITIES FOR RAINFALL AMOUNTS TO
EXCEED 0.25", 0.50", AND 1.00" FOR SELECT LOCATIONS ACROSS NORTH
CENTRAL, CENTRAL, AND SOUTHWEST MONTANA.
PRECIPITATION PROBABILITIES THRU SUNDAY NIGHT
LOCATION > 0.25" | > 0.50" | >1.00"
BROWNING 10% | 5% | <5%
CUT BANK 40% | 10% | 5%
HAVRE 60% | 20% | 10%
GREAT FALLS 85% | 50% | 10%
LEWISTOWN 90% | 45% | 10%
HELENA 80% | 40% | 5%
WHITE SULPHUR SPRINGS 85% | 45% | 10%
BOZEMAN 85% | 60% | 15%
DILLON 35% | 10% | 5%
ENNIS 90% | 65% | 20%
WEST YELLOWSTONE 95% | 90% | 45%
- MOLDAN
AVIATION
29/18Z TAF PERIOD
WIDESPREAD THUNDERSTORMS AND RAINSHOWERS WILL MOVE NORTH AND EAST
ACROSS THE REGION THIS AFTERNOON AND OVERNIGHT. VFR CONDITIONS
ARE PREDOMINANT HOWEVER MVFR CONDITIONS WILL EXIST FOR KWYS
THROUGH THE PERIOD FROM TRAINING SHOWERS AND THUNDERSTORMS.
STRONGER SHOWERS AND STORMS ACROSS SOUTHWEST AND CENTRAL MT COULD
PRODUCE TEMPORARY PERIODS OF IFR CONDITIONS WITHIN THE CORES.
PRIMARY THREATS FROM THESE STROMS WILL BE STRONG GUSTY OUTFLOW
WINDS, CLOUD TO GROUND LIGHTNING, AND LOCALIZED HEAVY RAINFALL.
FOR KGTF: VFR CONDITIONS WITH A 50% CHANCE FOR THUNDERSTORMS FROM
20Z TO 22Z PRODUCING GUSTS UP TO 40 KT AND MODERATE RAIN. WINDS
WILL BE OUT OF THE SOUTHWEST FOR MOST OF THE PERIOD WITH ERRATIC
OUTFLOW GUSTS THAT COULD HIT CROSSWIND EXCEEDANCE BRIEFLY FROM 20Z
TO 30/00Z. - AKINS
PRELIMINARY POINT TEMPS/POPS
GTF 50 65 45 77 / 90 50 0 0
CTB 46 61 44 74 / 60 10 0 0
HLN 46 67 43 78 / 80 20 0 0
BZN 47 67 39 78 / 70 70 0 0
WYS 36 62 30 71 / 80 90 0 0
DLN 44 69 38 79 / 70 30 0 0
HVR 51 68 47 77 / 80 60 10 0
LWT 47 64 42 77 / 80 90 0 0
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
HTTP://WWW.WEATHER.GOV/GREATFALLS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page