643
FXUS65 KTFX 191720
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1120 AM MDT SUN JUL 19 2026
AVIATION SECTION UPDATED.
KEY MESSAGES
- HOT, DRY, AND BREEZY CONDITIONS WILL GENERALLY PREVAIL TODAY
WITH ISOLATED TO SCATTERED SHOWER AND THUNDERSTORM ACTIVITY
MOSTLY CONFINED TO THE HIGHER TERRAIN OF FAR SOUTHWEST MT.
- A COLD FRONT WILL BRING NORTHERLY BREEZES, A BRIEF COOLDOWN,
AND MOSTLY DRY CONDITIONS ASIDE FROM A FEW STRAY SHOWERS OR
STORMS.
- SUMMER HEAT BUILDS AGAIN AND DAILY ROUNDS OF STORMS RETURN
HEADING TOWARDS THE MIDDLE OF THE WEEK.
DISCUSSION
/ISSUED 500 AM MDT SUN JUL 19 2026/
A MID- LEVEL TROUGH WILL CONTINUE TO MOVE EASTWARD THROUGH THE
CANADIAN PRAIRIES WILL BRING INCREASED WESTERLY FLOW ALOFT OVER
THE NORTHERN ROCKIES TODAY. 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
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 AFTERNOON AND EARLY
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
PRELIMINARY POINT TEMPS/POPS
GTF 93 57 84 60 / 0 0 0 10
CTB 85 56 80 57 / 0 0 0 20
HLN 93 57 87 61 / 0 0 10 0
BZN 93 57 91 58 / 0 0 0 0
WYS 87 49 91 50 / 20 0 20 20
DLN 90 55 88 55 / 0 0 20 20
HVR 93 58 87 58 / 0 0 0 10
LWT 89 55 82 54 / 10 0 0 0
TFX WATCHES/WARNINGS/ADVISORIES
NONE.
HTTP://WWW.WEATHER.GOV/GREATFALLS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page