383
FXUS65 KTFX 162040
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
Issued by National Weather Service Missoula MT
240 PM MDT Thu Jul 16 2026

.KEY MESSAGES...

 - Strong to severe thunderstorms today and Friday, with strong
   winds, hail ,and flash flooding possible.

 - Dry conditions on Sunday before daily chances for showers and
   thunderstorms return next week.

&&

.DISCUSSION...

 - Meteorological Overview:

A closed upper-level low along the Pacific Northwest coast keeps
us in a southwest flow aloft pattern through the rest of the week.
This pattern bringing a warm and unstable airmass will continue
daily chances for showers and thunderstorms through Saturday.
Strong to severe thunderstorms will be possible each afternoon
and evening through Saturday.

For the rest of today, isolated showers and thunderstorms have
developed over Southwest MT and the higher terrain. Instability
approaching 2,000 J/kg of CAPE with 30-50kts of bulk effective
wind shear, storms will be capable of becoming severe through the
evening. Large hail is the primary threat with lots of elevated
instability but severe wind gusts are also possible due to deep
vertical mixing and 1,000+ DCAPE. Storms will continue to move off
of the higher terrain and into the lower elevations over the next
few hours and become more scattered in coverage. PWATs nearing an
inch will also bring a flash flood threat for any storm producing
heavy rainfall, mainly for the Horse Gulch Burn Scar and urban
areas.

Friday`s storm threat is not too different, but storms converging
into clusters/a broken line will bring a primary wind threat, but
isolated large hail will be possible. Similar high PWATs also
bring another threat for flash flooding with heavy rainfall to the
Horse Gulch Burn Scar and urban areas. Saturday`s storm threat
will be more isolated, with best chances in Southwest MT.

Sunday keeps trending dry with that closed low moving to the north,
with hotter temperatures reaching into the 90s across lower
elevations. However, dry conditions don`t look to stay long as
another "dirty ridge" builds back in for the week, keeping daily
chances for showers and thunderstorms. -Wilson


&&

.AVIATION...
16/18Z TAF Period

Showers and thunderstorms will quickly develop across the
mountains of Southwest Montana and along the Continental Divide
between 19-21z this afternoon, with this activity then lifting
north and east over the adjacent plains and valleys through 03-06z
Friday. While most terminals have a chance of seeing
thunderstorms over this time frame the KHLN, KBZN, and KEKS
terminals have the highest chance of seeing strong to severe
thunderstorms, especially between 16/19z and 17/01z. Primary
threats with any severe thunderstorms will be wind gusts in excess
of 50kts and hail larger than 1" in diameter. - Moldan

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  61  95  61  95 /  20  30  70  10
CTB  59  89  59  91 /  50  40  50  10
HLN  62  93  62  93 /  40  50  70  20
BZN  58  93  57  92 /  30  40  60  10
WYS  49  85  49  85 /  20  50  80  20
DLN  55  88  55  89 /  50  40  50  10
HVR  62  97  62  97 /  40  10  60  10
LWT  56  89  56  90 /  40  10  70  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until midnight MDT tonight for Big Belt,
Bridger and Castle Mountains.

&&

$$
http://www.weather.gov/greatfalls