759
FXUS65 KTFX 171122
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
ISSUED BY NATIONAL WEATHER SERVICE MISSOULA MT
522 AM MDT FRI JUL 17 2026
KEY MESSAGES
- SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL MOVE IN A
SOUTHWEST TO NORTHEAST FASHION LATER THIS AFTERNOON THROUGH THE
EARLY OVERNIGHT HOURS.
- THUNDERSTORM HAZARDS WILL INCLUDE STRONG, GUSTY WINDS, HAIL,
AND TORRENTIAL DOWNPOURS CAPABLE OF LOCALIZED FLOODING.
- WARMER TEMPERATURES AND SLIGHTLY DRIER CONDITIONS MOVE IN FOR
THE WEEKEND, ALTHOUGH THERE WILL STILL BE WIDELY SCATTERED
SHOWER AND THUNDERSTORM ACTIVITY.
DISCUSSION
A SHORTWAVE EMBEDDED WITHIN A SOUTHWESTERLY FLOW ALOFT WILL
INTERACT WITH MONSOON MOISTURE AND AN UNSTABLE PROFILE FOR THE
DEVELOPMENT OF CLUSTERS TO BROKEN LINES OF THUNDERSTORMS MOVING
IN A SOUTHWEST TO NORTHEAST FASHION THIS AFTERNOON INTO TONIGHT.
THE MOST ROBUST CAPE OVER 1,500 J/KG WILL BE SLIGHTLY FARTHER EAST
OF THE 30 +KT BULK SHEAR AREA, BUT THERE WILL CERTAINLY ENOUGH
OVERLAP FOR AT LEAST SCATTERED STRONG TO SEVERE THUNDERSTORMS.
ADDITIONALLY, ANOMALOUSLY HIGH PWATS, GENERALLY BETWEEN AN INCH
AND AN INCH AND A HALF, WILL BE CAPABLE OF PRODUCING BRIEF PERIODS
WITH RAINFALL RATES IN THE HALF TO ONE INCH RANGE AND EVEN HIGHER
IN THE STRONGER CORES. A FLASH FLOOD WATCH WAS SENT OUT AGAIN FOR
THE HORSE GULCH BURN SCAR FOR THIS AFTERNOON AND EVENING. URBAN
AREAS THAT RECEIVE THESE HEAVIER RAINFALL RATES WILL ALSO BE
SUSCEPTIBLE TO LOCALIZED FLOODING, ESPECIALLY OVER CENTRAL AND
NORTH-CENTRAL MT, THOUGH CONFIDENCE WAS NOT QUITE HIGH ENOUGH FOR
ADDITIONAL FLOOD PRODUCTS AT THIS TIME.
SLIGHTLY DRIER AIR MOVES IN FOR THE WEEKEND AS THE FLOW ALOFT
BECOMES MORE WESTERLY AND PUSHES THE RICHEST MOISTURE OFF TO THE
EAST. THERE WILL BE ANOTHER SHORTWAVE THAT PASSES THROUGH AGAIN
ON SATURDAY, BUT IT WILL HAVE LESS CAPE AND MOISTURE TO INTERACT
WITH. THE WIDELY SCATTERED SHOWERS AND STORMS THAT DO DEVELOP
WILL CONTAIN GUSTY, TO LOCALLY STRONG WINDS WITH RH'S DROPPING
BACK DOWN TO THE TEENS SATURDAY AFTERNOON. SIMILAR CONDITIONS
PREVAIL FOR SUNDAY, THOUGH STORM COVERAGE MAY BE EVEN LESS THAN
SATURDAY.
ASIDE FROM A BRIEF COOLDOWN ON MONDAY THANKS TO A PASSING COLD
FRONT, TEMPERATURES WILL BE ON THE RISE THANKS TO HIGH PRESSURE
ALOFT BUILDING OVER THE GREAT BASIN AREA. THE NORTHERN ROCKIES
WILL STILL BE FAR ENOUGH NORTH FOR SHORTWAVES AND MOISTURE TO
COMPROMISE THE HIGH AND BRING AT LEAST WIDELY SCATTERED SHOWER AND
THUNDERSTORM ACTIVITY. - RCG
AVIATION
17/12Z TAF PERIOD
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL DEVELOP OVER
WEST AND SOUTHWEST MT BY AROUND 17/19Z BEFORE MOVING EAST AND
NORTHEAST THROUGH CENTRAL AND NORTH-CENTRAL MT DURING THE EVENING
AND EARLY OVERNIGHT HOURS. THUNDERSTORM HAZARDS WILL INCLUDE
STRONG, GUSTY WINDS, HAIL, AND TORRENTIAL DOWNPOURS. GENERAL VFR
CONDITIONS WILL PREVAIL, BUT THERE WILL BE MVFR AND EVEN BRIEF IFR
CONDITIONS BENEATH THE HEAVIER SHOWERS AND THUNDERSTORMS. THERE
WILL ALSO BE SOME PATCHY FOG DEVELOPMENT TOWARDS THE END OF THE
TAF PERIOD. - RCG
PRELIMINARY POINT TEMPS/POPS
GTF 95 61 95 61 / 30 50 10 40
CTB 89 59 91 58 / 40 60 10 0
HLN 93 62 93 62 / 50 50 20 30
BZN 93 57 92 58 / 40 40 10 40
WYS 85 49 85 48 / 50 60 20 30
DLN 88 55 89 55 / 50 60 10 20
HVR 97 62 97 62 / 10 50 10 20
LWT 89 56 90 57 / 10 70 10 30
TFX WATCHES/WARNINGS/ADVISORIES
FLASH FLOOD WATCH THROUGH THIS EVENING FOR BIG BELT, BRIDGER AND
CASTLE MOUNTAINS.
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