Helena Valley, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

057
FXUS65 KTFX 261927
AFDTFX

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

.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...

 - 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...
26/18Z TAF Period

VFR conditions will prevail throughout much of the 2618/2718 TAF
period, but periods of MVFR conditions due to reduced VIS from
precipitation and/or low CIGS beneath thunderstorms will be
possible. Shower and thunderstorms are expected to develop along
the Continental Divide between 19-20z, with this activity then
spreading east to northeast over the surrounding mountains,
valleys, and plains. Main window for any thunderstorm to impact a
given terminal exists between 26/20z and 27/04z, with the primary
hazard from any thunderstorm(s) that do impact a given terminal
being gusty and erratic winds of upwards of 40kts. Local mountain
obscuration is possible this afternoon and evening, but widespread
obscuration is not expected. - Moldan

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