289
FXUS65 KTFX 260548
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1148 PM MDT TUE AUG 25 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- TRENDING WARMER WITH INCREASED CHANCES FOR AFTERNOON AND
EVENING THUNDERSTORMS THE NEXT COUPLE DAYS.
- NOTE AS WARM THIS WEEKEND, PARTICULARLY ON SUNDAY.
UPDATE
/ISSUED 838 PM MDT TUE AUG 25 2026/
UPDATED FORECAST IS OUT. MAIN ADJUSTMENT WAS TO ADD THUNDERSTORMS
ACROSS SOUTHWEST MT FOR A FEW MORE HOURS THIS EVENING. OTHERWISE
THE REST OF THE FORECAST FOR TONIGHT IS ON TRACK.
LOOKING AHEAD, THERE IS THE POTENTIAL FOR AN ISOLATED SEVERE STORM
THE NEXT FEW DAYS AS THUNDERSTORMS MOVE THROUGH DURING THE
AFTERNOON/EVENING HOURS. THE MAIN IMPACT FROM ANY STORMS WILL BE
LIGHTNING AND STRONG WIND GUSTS. VERY WARM TEMPERATURES EXPECTED
THROUGH THURSDAY, BEFORE A SLOW COOLING TREND BEGINS ON FRIDAY.
BRUSDA
DISCUSSION
/ISSUED 838 PM MDT TUE AUG 25 2026/
- METEOROLOGICAL OVERVIEW:
UPPER LEVEL RIDGING CONTINUES TO BUILD IN ACROSS THE REGION AHEAD OF
TROUGHING MEANDERING OFF THE PACIFIC NW COAST. ALTHOUGH THE RIDGING
IS BUILDING IN, LINGERING MOISTURE ALOFT WILL COMBINE WITH DAYTIME
HEATING AND DEEP MIXING TO RESULT IN WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS THIS AFTERNOON AND EARLY EVENING, MAINLY NEAR AND
SOUTH OF I-90.
HEADING INTO WEDNESDAY THE RIDGE AXIS LOOKS TO SIT FIRMLY OVERHEAD,
WITH INFLUENCE FROM THE TROUGHING FROM THE WEST BEGINNING TO SNEAK
IN, PARTICULARLY NEAR THE CONTINENTAL DIVIDE. COVERAGE OF SHOWERS
AND THUNDERSTORMS INCREASES FURTHER NEAR THE CONTINENTAL DIVIDE.
GIVEN THE DRIER LOW-LEVELS, PRECIPITATION AMOUNTS DON'T LOOK
PARTICULARLY HIGH, WHICH WOULD RAISE CONCERN FOR POTENTIAL LIGHTNING
IGNITIONS.
RIDGING BEGINS TO SLIP EASTWARD THURSDAY, WHICH LOOKS TO LEAD TO
BOTH THE WARMEST DAY OF THE WEEK, AS WELL AS THE DAY WITH GREATEST
COVERAGE OF SHOWERS AND THUNDERSTORMS. INVERTED-V PROFILES SUGGEST
STRONG WIND GUSTS WILL BE THE GREATEST CONCERN FOR THUNDERSTORMS
THURSDAY.
UNCERTAINTY INCREASES TOWARD THE WEEKEND, THOUGH AT LEAST INITIALLY
CONFIDENCE REMAINS MODESTLY HIGH THAT A WEST-SOUTHWEST FLOW WILL BE
IN PLACE FRIDAY. BREEZY WINDS LOOK TO BE THE MOST LIKELY OUTCOME
FROM THIS SETUP, WITH LOWER CONFIDENCE IN ANY PRECIPITATION. AS FOR
THE WEEKEND, THERE LOOKS TO BE A BROAD UPPER LEVEL DISTURBANCE OVER
BC/AB AND VICINITY, WHICH LOOKS TO SEND A SMALLER EMBEDDED WAVE
TOWARD THE NORTHERN ROCKIES BY SUNDAY. TIMING AND TRACK OF THIS
SYSTEM WILL PLAY A LARGE ROLE IN WHETHER PRECIPITATION WILL BE MORE
LOCALIZED OR A BIT MORE WIDESPREAD THIS WEEKEND. NONETHELESS, THE
WEEKEND AND PARTICULARLY SUNDAY LOOK TO BE COOLER. -AM
- FORECAST CONFIDENCE & SCENARIOS:
THUNDERSTORM AND PRECIPITATION CHANCES:
THERE WILL BE DAILY CHANCES FOR THUNDERSTORMS ACROSS SOUTHWEST
MONTANA THROUGH THURSDAY THAT WILL SLOWLY SPREAD NORTH AS THE
WEEK CONTINUES. LOOKING AT MODEL SOUNDINGS, THERE ARE DEEP
INVERTED-V PROFILES WHICH INCREASES CONFIDENCE IN THESE
THUNDERSTORMS BEING ON THE DRIER SIDE. THIS MEANS THE MAIN THREATS
WILL BE LIGHTNING AND GUSTY/ERRATIC WINDS WHICH WILL PROVIDE
LITTLE RELIEF TO THE CURRENT FIRE SITUATION. FOR MORE ON THE
EXPECTED FIRE WEATHER CONCERNS, SEE THE FIRE WEATHER SECTION.
AS THE THUNDERSTORM POTENTIAL SPREADS INTO CENTRAL MONTANA, THERE
IS STILL AN EXPECTATION THAT MOST OF THESE THUNDERSTORMS WILL BE
ON THE DRIER SIDE WITH A HINT THAT SOME ISOLATED STRONG TO SEVERE
WEATHER IS POSSIBLE THURSDAY AFTERNOON. CURRENT MODEL RUNS
INDICATED AROUND 1000-1500 J/KG CAPE WITH AROUND 20-35KTS OF BULK
SHEAR. THERE IS STILL A BIT OF UNCERTAINTY WITH WHERE THE GREATEST
THREAT FOR SEVERE WEATHER WILL BE BUT THE MAIN CONCERN WITH ANY
THUNDERSTORM THAT DEVELOPS WILL BE STRONG WIND GUSTS.
EXTENDED FORECAST:
THERE IS DECENT AGREEMENT AMONGST THE MODELS ON A STRONG UPPER-LEVEL
TROUGH MOVING THROUGH THIS WEEKEND WHICH WILL BRING COOLER AND
BREEZY CONDITIONS TO THE REGION. LOOKING TOWARDS NEXT WEEK, THERE
IS AN INTERESTING POTENTIAL WITH CLUSTER GUIDANCE HINTING TOWARDS
POTENTIALLY MULTIPLE TROUGHS MOVING THROUGH THE AREA. IT IS FAR
TOO EARLY TO PIN DOWN THE FINER DETAILS OF WHAT IS TO OCCUR BUT
THERE IS HOPE OF FALL-LIKE CONDITIONS ON THE MORE DISTANCE
HORIZON.
-THOR
AVIATION
26/06Z TAF PERIOD
WILDFIRE SMOKE WILL LEAD TO PERIODS OF MOUNTAIN OBSCURATION ALONG
THE CONTINENTAL DIVIDE AND PORTIONS OF SOUTHWEST MONTANA OVER THE
NEXT 24 HOURS. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP
IN SOUTHWEST MONTANA AFTER 26/18Z AND BECOME MORE SCATTERED INTO
CENTRAL MONTANA AFTER 26/21Z. THUNDERSTORMS WILL LINGER ACROSS THE
REGION THROUGH AT LEAST 27/03Z AND START TAPERING OFF FURTHER
INTO THE EVENING WITH THE LOSS OF DAYTIME HEATING. THE MAIN
CONCERNS WILL BE LIGHTNING AND GUSTY/ERRATIC WINDS. MOUNTAIN
OBSCURATION WILL BE A CONCERN WHEREVER SHOWERS/THUNDERSTORMS
DEVELOP.
FOR KGTF: WILDFIRE SMOKE IS GENERALLY EXPECTED TO REMAIN ALOFT AND
IMPACT SLANTWISE VISIBILITY THROUGH THE PERIOD WITH NO MAJOR
IMPACTS TO SURFACE VISIBILITY EXPECTED. WINDS WILL REMAIN LIGHT
THROUGH THE NIGHT INTO THE MID-MORNING WITH A SLIGHT PICK UP TO
6-8KTS OUT OF THE EAST EXPECTED AFTER 26/20Z.
THE MAIN CONCERN FOR WEDNESDAY WILL BE HOW THE THUNDERSTORMS
DEVELOP AND PROGRESS ACROSS THE REGION. THE LATEST HI-RES MODELS
SHOW THUNDERSTORMS SPLITTING TO THE NORTH AND SOUTH OF GREAT FALLS
WITH AROUND A 30% PROBABILITY OF A DIRECT IMPACT TO KGTF. THE MAIN
CONCERN WOULD BE IF A THUNDERSTORM STARTS TO FOLLOW THE I-15
CORRIDOR FROM THE SOUTH OFF THE MOUNTAINS WHICH WOULD GREATLY
INCREASE THE CHANCES THAT IT IMPACTS THE TERMINAL. EVEN WITHOUT A
DIRECT IMPACT, THERE IS A CONCERN THAT ANY THUNDERSTORM IN THE
GENERAL AREA COULD PRODUCE AN OUTFLOW BOUNDARY THAT RESULTS IN A
STRONG CROSSWIND AT THE AIRPORT. IN TERMS OF TIMING, THUNDERSTORMS
ARE EXPECTED TO START MOVING OFF THE CONTINENTAL DIVIDE BETWEEN
26/22Z AND 27/01Z AND REACH THE KGTF VICINITY BY AROUND 27/00Z TO
27/03Z. -THOR
FIRE WEATHER
THROUGH WEDNESDAY, THERE ARE ONLY MARGINAL CONCERNS FOR ELEVATED
FIRE WEATHER WITH TEMPERATURES GRADUALLY WARMING AND WINDS GENERALLY
EXPECTED TO BE ON THE CALMER SIDE. THE ONLY WILD CARD THAT COULD
POTENTIALLY CREATE DIFFICULT CONDITIONS WILL BE THE DAILY CHANCES
FOR DRY THUNDERSTORMS. THE PRIMARY FOCUS ON TUESDAY WILL BE
SOUTHWEST MONTANA WITH THE THREAT FOR DRY THUNDERSTORMS SPREADING
INTO PORTIONS OF CENTRAL MONTANA BY WEDNESDAY. WITH THIS BEING THE
ONLY MODE OF CONCERN FOR FIRE WEATHER, NO PRODUCTS WILL BE ISSUED AT
THIS TIME. BUT GIVEN HOW DRY THE FUELS ARE FOLKS SHOULD CONTINUE TO
TAKE ALL MEASURES TO PREVENT SPARKS FROM OCCURRING.
THURSDAY CURRENTLY LOOKS THE MOST CONCERNING FOR POTENTIAL ELEVATED
FIRE WEATHER CONDITIONS. GUSTY CONDITIONS IN SOUTHWEST AND PORTIONS
OF CENTRAL MONTANA, COMBINED WITH A MORE ROBUST CHANCE FOR DRY
THUNDERSTORMS, AND TEMPERATURES RANGING FROM THE UPPER 80S TO MID
90S COULD MAKE THINGS DIFFICULT FOR ONGOING FIRE OPERATIONS. RIGHT
NOW THE HDWI IS ONLY HIGHLIGHTING THE PROBABILITY OF EXCEEDING THE
75TH PERCENTILE WITH ABOUT A 20% CHANCE FOR SOME LOCATIONS TO EXCEED
THE 90TH PERCENTILE. ADDITIONALLY, A FEW THUNDERSTORMS MAY BE ON
THE DRY SIDE ACROSS PORTIONS OF SW MT THURSDAY. SO AT THIS TIME,
CRITICAL FIRE WEATHER CONDITIONS ARE NOT HIGH CONFIDENCE. BUT
THIS WILL NEED TO BE MONITORED CLOSELY AS THE WILD CARD OF DRY
THUNDERSTORM COVERAGE AND INTENSITY MAY ACT AS A NUDGE FACTOR
TOWARDS MORE CRITICAL CONDITIONS. -THOR/AM
PRELIMINARY POINT TEMPS/POPS
GTF 55 90 58 92 / 10 20 30 20
CTB 50 87 53 87 / 0 20 30 20
HLN 55 90 55 88 / 20 30 30 40
BZN 52 88 52 88 / 20 20 30 30
WYS 42 81 41 81 / 30 30 30 30
DLN 51 86 50 84 / 20 30 30 20
HVR 53 93 60 96 / 0 0 10 20
LWT 52 88 56 92 / 10 20 30 30
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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