389
FXUS65 KTFX 121436
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
836 AM MDT SUN JUL 12 2026
KEY MESSAGES
- HOT TEMPERATURES CONTINUE FOR ANOTHER DAY BEFORE COOLING
OFF SLIGHTLY DURING THE WORKWEEK.
- DRY, BREEZY TO WINDY, AND HOT CONDITIONS WILL BRING ELEVATED
FIRE DANGER OVER SOUTHWEST MONTANA THIS AFTERNOON.
- DAILY ROUNDS OF SHOWER AND THUNDERSTORM ACTIVITY RETURNS BY
MONDAY AND WILL BE MOST WIDESPREAD TUESDAY THROUGH THURSDAY.
- SOME STORMS WILL BE ON THE STRONGER SIDE AND MAY CONTAIN STRONG,
GUSTY WINDS, HAIL, AND TORRENTIAL DOWNPOURS CAPABLE OF LOCALIZED
FLOODING.
UPDATE
CURRENT FORECAST IS ON TRACK. CLOUD COVER OVER NORTH CENTRAL MT IS
KEEPING TEMPERATURES FROM RISING TOO QUICKLY THIS MORNING.
HOWEVER, CLOUDS SHOULD BREAK A BIT LATE MORNING/EARLY
AFTERNOON...ALLOWING TEMPERATURES TO RISE TOWARDS FORECAST HIGHS
FOR TODAY.
OTHER CONCERN IS THE POTENTIAL FOR A DRY THUNDERSTORM, THAT COULD
PRODUCE A STRONG WIND GUST. OVERALL THE PROBABILITY IS LESS THAN
20 PERCENT RIGHT NOW, SO ANY THUNDERSTORM ACTIVITY TODAY WILL BE
ISOLATED, BUT BECAUSE OF HOW HIGH BASED THE STORMS WILL BE, ANY
STORMS THAT DO DEVELOP COULD PRODUCE A STRONG WIND GUSTS.
LOOKING AHEAD, THUNDERSTORM ACTIVITY WILL BECOME MORE WIDESPREAD
BY MONDAY NIGHT INTO TUESDAY, WITH SOME STORMS PRODUCING HEAVY
RAINFALL.
DISCUSSION
/ISSUED 533 AM MDT SUN JUL 12 2026/
- METEOROLOGICAL OVERVIEW:
RIDGING ALOFT WILL MAINTAIN HOT AND DRY CONDITIONS AGAIN TODAY
WHILE SOUTHWESTERLY FLOW STRENGTHENS ALOFT. DEEP LAYER MIXING WILL
TRANSFER THE 30 TO 40 KT H700 WINDS TO THE SURFACE ESPECIALLY
OVER SOUTHWEST MT WHERE ELEVATED FIRE WEATHER CONDITIONS WILL BE
PRESENT LATER TODAY. A SUBTLE SHORTWAVE WILL CLIP THE NORTHWESTERN
PORTION OF THE FORECAST AREA AND WILL BRING A NORTHWESTERLY WIND
SHIFT TO MOST LOCALES THIS AFTERNOON AND EVENING, ALTHOUGH THERE
WILL NOT BE COOLING RELIEF ON THE BACKSIDE OF THIS FEATURE.
THE 597 DM HIGH WILL MOVE EASTWARD TOWARDS THE PLAINS WITH
SOUTHWESTERLY FLOW ALOFT BECOMING ENTRENCHED OVER THE NORTHERN
ROCKIES BY MONDAY. THIS WILL ADVECT MONSOON MOISTURE IN FROM THE
DESERT SOUTHWEST AND INCREASE PWATS UP THE 0.90 TO 1.30 INCH RANGE
BY TUESDAY AND WEDNESDAY ACCORDING TO THE NORTH AMERICAN ENSEMBLE
FORECAST SYSTEM (NAEFS). THIS MOISTURE WILL INTERACT WITH PASSING
SHORTWAVES AND CAPE GENERALLY BETWEEN 700 AND 1500 J/KG FOR DAILY
ROUNDS OF SCATTERED SHOWERS AND THUNDERSTORMS, WITH SOME STORMS
CONTAINING STRONG, GUSTY WINDS, HAIL, AND TORRENTIAL DOWNPOURS IN
ADDITION TO CLOUD TO GROUND LIGHTNING. TEMPERATURES WILL COOL
SLIGHTLY FROM THE WEEKEND WITH THE ADDED CLOUDS AND CONVECTIVE
ACTIVITY.
A MAJORITY OF ENSEMBLES HIGHLIGHT THE THE 597 DM RIDGE MIGRATING
BACK TOWARDS THE GREAT BASIN BY EARLY NEXT WEEK, BUT THE NORTHERN
ROCKIES WILL REMAIN ON THE PERIPHERY OF THIS FEATURE AND STILL
MAINTAIN AN UNSTABLE WEST TO SOUTHWESTERLY FLOW ALOFT FOR AT LEAST
ISOLATED TO WIDELY SCATTERED SHOWER AND THUNDERSTORM ACTIVITY.
- RCG
- FORECAST CONFIDENCE & SCENARIOS:
HOT TEMPERATURES AND BREEZY, DRY CONDITIONS TODAY...
DEEP LAYER MIXING AND STRONGER SOUTHWESTERLY FLOW ALOFT WILL
INCREASE SURFACE WINDS TODAY WHILE MAINTAINING HOT AND DRY
CONDITIONS. THE WINDS WILL BE STRONGEST FOR SOUTHWEST MT AREAS
EAST OF I15, ESPECIALLY THE SOUTH TO NORTH ORIENTED VALLEYS WHERE
ISOLATED GUSTS OVER 50 MPH WILL BE PLAUSIBLE. THE PRIMARY IMPACT
WILL BE ELEVATED FIRE WEATHER CONDITIONS, SEE THE FIRE WEATHER
SECTION FOR MORE INFORMATION.
AS FAR AS TEMPERATURES GO, TODAY WILL BE THE HOTTEST DAY WITH
HIGHS GENERALLY RUNNING BETWEEN 95 AND 105 DEGREES. THERE WILL BE
SOME ISOLATED AREAS ALONG THE MISSOURI RIVER BREAKS AND IN THE
FORT BELKNAP AREA THAT MAY SEE HIGHS EXCEEDING 105. TEMPERATURES
REMAIN VERY WARM HEADING INTO THE WORKWEEK, ALTHOUGH NOT QUITE AS
INTENSE. NO CHANGES WERE MADE TO THE INHERITED HEAT ADVISORIES.
DAILY ROUNDS OF SHOWERS AND THUNDERSTORMS RETURN FOR MUCH OF THE
UPCOMING WEEK...
INCREASING MOISTURE AND INSTABILITY MAY BRING A FEW ISOLATED
GUSTY SHOWERS AND THUNDERSTORMS AS EARLY AS LATE THIS AFTERNOON
AND EVENING, ESPECIALLY OVER CENTRAL AND NORTH-CENTRAL MT.
OTHERWISE, MONDAY THROUGH THURSDAY WILL SEE THE MOST WIDESPREAD
SHOWERS AND THUNDERSTORMS. WHILE ALL THESE DAYS WILL NEED TO BE
MONITORED FOR LOCALIZED STRONG, GUSTY WINDS, HAIL, AND TORRENTIAL
DOWNPOURS, TUESDAY AND WEDNESDAY LOOK TO HAVE ANOMALOUSLY HIGH
PWATS THAT MAY EXCEED 1.25 INCHES OVER CENTRAL AND NORTH-CENTRAL
MT. THESE DAYS WILL BE HIGHEST AT RISK FOR LOCALIZED FLASH
FLOODING, ESPECIALLY FLOOD SENSITIVE AREAS LIKE BURN SCARS AND
URBAN AREAS. THIS HAS PROMPTED THE WEATHER PREDICTION CENTER TO
HIGHLIGHT MUCH OF THE FORECAST AREA WITH A MARGINAL RISK (5 TO 15%
CHANCE) FOR FLASH FLOODING FOR DAYS 3 AND 4. - RCG
AVIATION
12/12Z TAF PERIOD
VFR CONDITIONS PREVAIL THROUGH THE TAF PERIOD WITH A GRADUAL
INCREASE IN HIGH LEVEL CLOUDS BY THIS AFTERNOON. CUMULUS
DEVELOPMENT THIS AFTERNOON WILL PROGRESS TO HIGH-BASED SHOWERS
AND POTENTIALLY AN ISOLATED THUNDERSTORM OR TWO ACROSS MAINLY
EASTERN PORTIONS OF NORTH-CENTRAL MT. THE MAIN RISK WITH THIS IS
THE POTENTIAL FOR GUSTY AND ERRATIC DOWNDRAFT WINDS, PARTICULARLY
NEAR KLWT AND KHVR. SOUTH TO SOUTHWEST SURFACE WINDS INCREASE AT
MOST TERMINALS BY EARLY THIS AFTERNOON WITH A WIND SHIFT TO THE
NORTHWEST OCCURRING FROM NORTH TO SOUTH ACROSS THE AREA LATE THIS
AFTERNOON THROUGH THIS EVENING. HOENISCH
FIRE WEATHER
FIRE WEATHER CONCERNS FOR TODAY WILL CONTINUE TO BE MOST IMPACTFUL
ACROSS SOUTHWEST MT WHERE WINDS WILL BE STRONGER AND FUELS ARE MOST
RECEPTIVE. PROBABILITIES FOR WIND GUSTS IN EXCESS OF 40 MPH INCREASE
TO 60% OR GREATER OVER MUCH OF SOUTHWEST MT BY THIS AFTERNOON,
ESPECIALLY FOR LOCATIONS EAST OF I15. THIS INCLUDES AREAS AS FAR
NORTH AS THE VALLEYS OF BROADWATER AND MEAGHER COUNTIES. THE
COMBINATION OF THE WINDS WITH NEAR RECORD AFTERNOON TEMPERATURES AND
CRITICALLY LOW HUMIDITY HAVE RESULTED IN THE HOT-DRY-WINDY INDEX
EXCEEDING THE 90TH PERCENTILE OVER THESE AREAS THIS AFTERNOON FOR
ELEVATED FIRE WEATHER CONDITIONS. ADDITIONALLY, THERE WILL BE A WEAK
BOUNDARY THAT BRINGS A NORTHWESTERLY WIND SHIFT DURING THE
EVENING HOURS. - RCG
PRELIMINARY POINT TEMPS/POPS
GTF 100 62 95 64 / 10 20 20 20
CTB 91 61 90 63 / 10 10 10 20
HLN 100 64 96 67 / 10 20 20 20
BZN 103 60 96 61 / 10 10 10 20
WYS 97 50 95 52 / 0 0 10 0
DLN 99 57 93 58 / 10 0 20 20
HVR 102 63 96 66 / 10 30 10 30
LWT 104 59 93 59 / 10 20 10 10
TFX WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY UNTIL 9 PM MDT MONDAY FOR BEARS PAW MOUNTAINS AND
SOUTHERN BLAINE-CANYON FERRY AREA-CASCADE COUNTY BELOW 5000FT-
EASTERN PONDERA AND EASTERN TETON-EASTERN TOOLE AND LIBERTY-
FERGUS COUNTY BELOW 4500FT-GALLATIN VALLEY-GATES OF THE
MOUNTAINS-HELENA VALLEY-HILL COUNTY-JUDITH BASIN COUNTY AND
JUDITH GAP-MADISON RIVER VALLEY-MISSOURI HEADWATERS-NORTHERN
BLAINE COUNTY-SOUTHERN HIGH PLAINS-WESTERN AND CENTRAL CHOUTEAU
COUNTY.
HTTP://WWW.WEATHER.GOV/GREATFALLS
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