173
FXUS65 KTFX 270027
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
627 PM MDT Sat Jul 26 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Daily rounds of showers and thunderstorms through the upcoming
   week, most focused on the afternoon and early evening.

 - The risk for stronger thunderstorms will be around most days, with
   gusty winds being the greatest threat most days.

 - As better moisture works in toward the middle of the week,
   concerns for localized heavy rain from thunderstorms will
   increase.

&&

.DISCUSSION...
/Issued 127 PM MDT Sat Jul 26 2025/

 - Meteorological Overview:

Southwesterly flow aloft will persist across the Northern Rockies
over the upcoming week, which will promote daily afternoon and
evening showers and thunderstorms. Convective initiation most days
looks to be over terrain in Central and Southwest Montana, with
resulting showers and thunderstorms moving northeastward with time.

Looking toward the work week, better precipitable water eventually
works in, which will help the more robust thunderstorms produce
higher rainfall rates/amounts, though storm motion does not appear
to be overly slow any specific day.

The main threat with thunderstorms that form appears to be gusty
winds most days, with a lesser concern for hail. Today is no
exception - as thunderstorms develop across portions of Southwest
Montana and shift northeastward, the risk for strong to severe wind
gusts will increase. This risk continues onto the plains this
evening, eventually waning after sunset. -AM

 - Forecast Confidence & Scenarios:

Confidence in the areas with the best chance for stronger
thunderstorm decreases step by step Sunday onward. These details
will become more clear once convective details from the prior day
play out.

EFI suggests as we get deeper into the work week, convective energy
increases in magnitude, becoming unusually high by Wednesday (EFI
pushing above 0.9 with a SoT between 1 and 2). While a much lesser
signal, QPF SoT over a similar timeframe does show pockets of 0,
indicating a low end chance for anomalously high precipitation
associated with the thunderstorms that are forecast to develop. -AM

&&

.AVIATION...
27/00Z TAF Period

Main concerns this evening deal with convection and gusty outflow
winds. Storms/winds will likely affect GTF/HLN/LWT through mid
evening. Storms could affect HFV later this evening with a 30%
probability. BZN/EKS should continue to see northerly winds weaken
this evening. Some models are showing some late overnight/early
morning light showers but confidence is too low at this time to
mention in TAFs. Otherwise, trying to time next round of
convection for tomorrow afternoon with many sites not seeing
convection until after 00z Mon. -DV

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  57  84  56  83 /  60  20  30  20
CTB  51  76  52  75 /  20  20  20  30
HLN  56  86  56  86 /  40  30  30  30
BZN  51  90  51  88 /  20  20  20  20
WYS  39  81  40  83 /  10   0   0  20
DLN  47  85  48  84 /  20  30  20  20
HVR  56  84  57  83 /  40  10  30  60
LWT  54  82  52  77 /  50  20  40  50

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

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