509
FXUS65 KTFX 192350
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
550 PM MDT SUN JUL 19 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- SMOKY CONDITIONS FROM FIRES BURNING ACROSS THE PACIFIC NORTHWEST
ARE LIKELY TO LINGER ACROSS SOUTHWEST THROUGH NORTH CENTRAL
MONTANA INTO THE DAY ON MONDAY.
- A COLD FRONT WILL BRING NORTHERLY BREEZES, A BRIEF COOLDOWN, AND
MOSTLY DRY CONDITIONS ASIDE FROM A FEW STRAY SHOWERS OR STORMS
ON MONDAY.
- SUMMER HEAT BUILDS AGAIN AND DAILY ROUNDS OF STORMS RETURN
HEADING TOWARDS THE MIDDLE OF THE WEEK.
DISCUSSION
/ISSUED 1252 PM MDT SUN JUL 19 2026/
- METEOROLOGICAL OVERVIEW:
A MID- LEVEL TROUGH WILL CONTINUE TO MOVE EASTWARD THROUGH THE
CANADIAN PRAIRIES WILL BRING INCREASED WESTERLY FLOW ALOFT OVER THE
NORTHERN ROCKIES THROUGH THE EARLY EVENING HOURS . DEEP LAYER MIXING
WILL HELP TRANSFER THE STRONGER 30 TO 40 KT H700/H500 FLOW TO THE
SURFACE FOR BREEZY TO WINDY CONDITONS TODAY, ESPECIALLY ALONG THE
ROCKY MOUNTAIN FRONT AND THE PLAINS. IN ADDITION TO THE DRY WESTERLY
BREEZES, RIDGING ALOFT, CURRENTLY CENTERED OVER THE GREAT BASIN,
WILL CONTINUE TO MAINTAIN HOT TEMPERATURES. ALTHOUGH FUELS ARE NOT
QUITE DRY ENOUGH FOR WIDESPREAD FIRE WEATHER CONCERNS, A DAY LIKE
TODAY WILL ACCELERATE THE CURING PROCESS.
THE DRIER WESTERLY FLOW ALOFT WILL ALSO SLOW DOWN SHOWER AND
THUNDERSTORM ACTIVITY, BUT ML CAPE WILL GENERALLY BE RUNNING BETWEEN
500 AND 800 J/KG OVER THE SOUTHWEST. WITH LITTLE FORCING AVAILABLE,
WIDELY SCATTERED SHOWERS AND STORMS WILL MOSTLY BE CONFINED TO FAR
SOUTHWESTERN AREAS ALONG THE MT/ID/WY BORDERS. IF OUTFLOW BOUNDARIES
OR OTHER LIFTING MECHANISMS BECOME STRONG ENOUGH TO ERODE THE 20 TO
50 J/KG OF INHIBITION, THEN WIDELY SCATTERED STORMS MAY DEVELOP OVER
MUCH OF THE SOUTHWEST AND EVEN CENTRAL AREAS SOUTHEAST OF A HELENA
TO LEWISTOWN LINE; HOWEVER, THE CHANCES FOR THIS OCCURRING ARE
RUNNING LESS THAN 20% AT THIS TIME. ANY STORM THAT DOES DEVELOP WILL
BE CAPABLE OF STRONG, GUSTY WINDS, HAIL, AND DOWNPOURS IN ADDITION
TO CLOUD TO GROUND LIGHTNING.
ANOTHER TROUGH RUNNING ALONG THE CANADIAN BORDER WILL SEND A
CANADIAN SURFACE FRONT THROUGH THE FORECAST AREA AND WILL BRING A
NORTHERLY WIND SHIFT AND A BRIEF COOLDOWN TONIGHT INTO MONDAY. THERE
WILL ALSO BE VARIABLE CLOUDS AND PERHAPS AN ISOLATED SHOWER OR
STORM. RIDGING ALOFT STRENGTHENS AND BRINGS A RETURN TO HOT
CONDITIONS HEADING TOWARDS THE MIDDLE OF THE WEEK. PASSING
SHORTWAVES INTERACTING WITH RICH MONSOON MOISTURE WILL ALSO INCREASE
DAILY SHOWER AND THUNDERSTORM ACTIVITY, ALONG WITH SEVERE WEATHER
AND LOCALIZED FLOODING CONCERNS. SOUTHWESTERLY FLOW ALOFT BECOMES
MORE ESTABLISHED OVER THE NORTHERN ROCKIES BY NEXT WEEKEND. THIS
WILL DO LITTLE TO COOL TEMPERATURES, BUT WILL BRING DRIER AIR IN AND
INCREASE WINDS FOR ELEVATED FIRE WEATHER CONCERNS DEPENDING ON THE
MID-WEEK RAINFALL QUALITY. - RCG
- FORECAST CONFIDENCE & SCENARIOS:
HOT TEMPERATURES FROM THURSDAY THROUGH NEXT SUNDAY...
ECMWF EFIS, WITH RESPECT TO HIGH TEMPERATURES, INDICATE THE
POTENTIAL FOR AN UNUSUAL PERIOD OF HEAT ACROSS MOST OF THE NORTHERN
ROCKIES THROUGHOUT THE PERIOD. WHILE THESE VALUES ARE NOT
EXCEPTIONALLY HIGH, GENERALLY BETWEEN 0.5 TO 0.7, THERE ARE SOME
LOCATIONS THAT WILL BE APPROACHING 0.8 (VERY UNUSUAL) ALONG THE
ROCKY MOUNTAIN FRONT ON THURSDAY. THE FACT THAT THE END OF JULY IS
THE PEAK FOR AVERAGE HIGH TEMPERATURES IS CONCERNING GIVEN THAT MOST
LOCATIONS AVERAGE ANYWHERE FROM THE MID-80S TO NEAR 90 DEGREES, WITH
THE EFI VALUES SUGGESTING TEMPERATURES AT LEAST IN THE 90S FOR ALL
LOCATIONS. NBM5.0 PROBABILITIES FOR HIGH TEMPERATURES IN EXCESS OF
100 DEGREES RANGE FROM A 10-50% CHANCE ON THURSDAY OVER THE PLAINS,
30-80% (PLAINS) AND 15-30% (VALLEYS) ON FRIDAY, 30-70% (PLAINS) AND
10-40% (VALLEYS) ON SATURDAY, AND 20-50% (PLAINS) AND 10-20%
(VALLEYS) ON SUNDAY.
GUSTY WINDS AND ELEVATED FIRE WEATHER CONDITIONS ON FRIDAY AND
SATURDAY...
CROSS BARRIER FLOW WILL BEGIN TO INCREASE THROUGH THE END OF THE
WORK WEEK AND INTO THE WEEKEND AS UPPER LEVEL RIDGING FLATTENS, WITH
H700 WINDS INCREASING TO BETWEEN 25-35KTS WHICH IS 1 TO NEARLY 2
STANDARD DEVIATIONS ABOVE NORMAL FOR THE ROCKY MOUNTAIN FRONT.
NBM5.0 PROBABILITIES SUPPORT A 35-70% CHANCE FOR WIND GUSTS TO
EXCEED 34KTS ON BOTH DAYS, WITH A 10-30% CHANCE TO EXCEED 43KTS.
THESE GUSTY WINDS COMBINED WITH HOT TEMPERATURES WILL LEAD TO
ELEVATED FIRE WEATHER CONDITIONS ALONG THE ENTIRE ROCKY MOUNTAIN
FRONT, MOST NOTABLY ACROSS FIRE WEATHER ZONES 112. - MOLDAN
AVIATION
19/18Z TAF PERIOD
INITIAL CONCERN THIS TAF PERIOD WILL BE FOR GUSTY WEST WINDS IN MANY
AREAS WITH WILDFIRE SMOKE IMPACTING VISIBILITY ACROSS THE REGION.
WHILE SURFACE VISIBILITY LOOKS TO REMAIN VFR, SOME SLANT RANGE
VISIBILITY ISSUES MAY ARISE WHERE SMOKE IS MOST DENSE ALOFT. THE
NEXT CONCERN IS FOR A FEW SHOWERS AND THUNDERSTORMS NEAR THE IDAHO
BORDER BETWEEN MONIDA PASS AND KWYS THIS EVENING, CAPABLE OF
GUSTY AND ERRATIC WINDS. ATTENTION THEN TURNS TO A COLD FRONT
MOVING SOUTH OVER THE PLAINS TONIGHT INTO MONDAY MORNING, SHIFTING
WINDS TO A MORE NORTHWESTERLY DIRECTION. -AM/LUDWIG
PRELIMINARY POINT TEMPS/POPS
GTF 56 83 60 85 / 0 0 10 0
CTB 55 79 57 81 / 0 0 20 0
HLN 57 86 61 87 / 0 10 0 0
BZN 56 91 57 88 / 0 0 0 10
WYS 50 90 50 86 / 0 10 10 50
DLN 54 87 54 85 / 0 20 20 10
HVR 56 87 58 86 / 0 0 10 0
LWT 54 82 54 81 / 0 0 0 0
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
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