151
FXUS65 KTFX 040434
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1034 PM MDT Sun Aug 3 2025

Aviation Section Updated.

.KEY MESSAGES...

 - This afternoon and evening there will be isolated showers and
   thunderstorms along the Hi-Line and along the Montana-Idaho
   Border in Southwestern Montana.

 - More widespread showers and thunderstorms return on Monday and
   Tuesday with isolated strong to severe thunderstorms Monday
   afternoon and evening.

 - Temperatures will remain near seasonal averages for most of
   this week before a brief cool-down Friday through Saturday.

&&

.DISCUSSION...
/Issued 552 PM MDT Sun Aug 3 2025/

 - Meteorological Overview:

This afternoon the upper-level ridge remains over North-central,
Central, and Southwestern Montana. An upper-level shortwave will
move through the upper-level flow which will bring chances for
showers and thunderstorms to the Hi-Line and Southwestern Montana
along the Montana/Idaho Border this afternoon and evening. On Monday
the upper-level ridge remains over North-central, Central, and
Southwestern Montana. Monday afternoon and evening a strong, quick-
moving shortwave will move through Southwest to North-central
Montana. This will bring showers and thunderstorms to the area
Monday afternoon and evening. Isolated thunderstorms will be strong
to severe with the greatest risk for strong wind gusts due to
inverted soundings with DCAPE values well in excess of 1000. On
Monday storms will begin in Southwestern Montana in the early
afternoon spreading northeastward to the Hi-Line by the evening.
Storms could linger into early Tuesday morning.

On Tuesday there will be a quick moving upper-level shortwave trough
over North-central, Central, and Southwestern Montana. This will
bring another round of showers and thunderstorms primarily to North-
central Montana. On Wednesday there will be upper-level zonal flow
over North-central, Central, and Southwestern Montana which will dry
out the area. On Thursday an upper-level ridge builds back in over
North-central, Central, and Southwestern Montana before an upper-
level trough associated with a surface cold front begins to move
towards Montana. This will bring showers and thunderstorms to the
area on Thursday afternoon and evening. On Friday the upper-level
trough will remain over North-central, Central, and Southwestern
Montana. On Friday due to the surface cold front temperatures will
be well-below seasonal averages across the area. On Saturday an
upper-level ridge begins to build back in over North-central,
Central, and Southwestern Montana.

 - Forecast Confidence & Scenarios:

This afternoon and evening there is a 30 - 40% chance for
thunderstorms across Southwestern Montana and along the Hi-Line. On
Monday there is a 40 - 60% chance for thunderstorms across North-
central, Central, and Southwestern Montana. On Monday the Storm
Prediction Center has issued a Marginal Risk (5% chance for wind
gusts in excess of 58 mph and/or hail with a diameter of 1 inch or
greater within 25 miles of point) for all of North-central, Central,
and Southwestern Montana except for Glacier County, Western Teton
County, and Western Pondera County. On Tuesday there is a 15 - 40%
chance for thunderstorms across North-central, Central, and
Southwestern Montana. On Thursday and Friday there is a 25 - 40%
chance for thunderstorms across North-central, Central, and
Southwestern Montana.

At the end of this forecast period there is high confidence that
there will be an upper-level trough that will bring well below
seasonal averages for temperatures to the area on Friday and
Saturday. -IG

&&

.AVIATION...
04/06Z TAF Period

Initial concerns this TAF period will be for a few showers lifting
northeastward from Southwest Montana into early Monday. Otherwise
attention turns to Monday afternoon, when widespread showers and
thunderstorms develop across the region. Gusty winds, lightning, and
hail will all be a concern in the strongest thunderstorms that form.
There does look to be at least a low-end threat for showers and
thunderstorms continuing into the overnight on the plains, but
confidence in the when/where was too low to warrant much mention of
that in TAFs at this time. -AM

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  56  85  55  80 /   0  40  70  20
CTB  51  78  54  74 /  20  50  60  30
HLN  56  84  53  81 /  10  40  70  10
BZN  51  87  48  83 /  20  40  40  10
WYS  40  80  38  75 /  30  30  30   0
DLN  48  81  45  79 /  30  50  30   0
HVR  56  88  58  78 /  20  50  90  50
LWT  54  84  51  75 /  10  50  80  20

&&

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

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