770
FXUS65 KTFX 280543
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1143 PM MDT Fri Jun 27 2025

Aviation Section Updated.

.KEY MESSAGES...

 - This afternoon and evening there will be isolated showers and
   thunderstorms with a few strong to severe thunderstorms.

 - Saturday through early next week it drys out and warms up.

 - Wednesday through the end of the work week there will be daily
   chances for showers and thunderstorms.

&&

.UPDATE...
/Issued 741 PM MDT Fri Jun 27 2025/

Showers and isolated thunderstorms are slowly diminishing in
coverage in the Big Sky/Ennis/West Yellowstone area this evening.
Expect this trend to continue into the night, though a few
lingering elevated showers cannot be ruled out in similar areas,
as well as northeastward toward Lewistown.

Gusty winds over the plains look to diminish after sunset,
becoming gusty again mid-morning Saturday. -AM

&&

.DISCUSSION...
/Issued 741 PM MDT Fri Jun 27 2025/

 - Meteorological Overview:

This afternoon the upper-level flow over North-central, Central, and
Southwestern Montana will be zonal. This combined with a weak
shortwave will bring another round of showers and thunderstorms to
North-central, Central, and Southwestern Montana this afternoon and
evening. Most of the storms will be in Central and North-central
Montana east of I-15. Isolated storms in Judith Basin and Fergus
County will be strong to severe this afternoon through this evening.
The zonal flow will remain over the area on Saturday. Along the Hi-
Line there will isolated showers tomorrow afternoon and evening. Due
to a strong surface pressure gradient this afternoon and tomorrow
along the Rocky Mountain Front and adjacent pains and in
Southwestern Montana this afternoon it will be windy.

On Sunday an upper-level ridge builds in over North-central,
Central, and Southwestern Montana. This will gradually warm up
temperatures and bring mostly dry weather to the area on Sunday. On
Monday the upper-level ridge remains over North-central, Central,
and Southwestern Montana which will keep mostly dry weather and warm
temperatures up further. On Tuesday the upper-level ridge remains
over North-central, Central, and Southwestern Montana. This combined
with southwest flow aloft will bring showers and thunderstorms to
the area Tuesday afternoon and evening. Wednesday through next
Friday passing upper-level disturbances combined with the upper-
level ridge over North-central, Central, and Southwestern Montana
will bring daily chances for showers and thunderstorms to the
area.

 - Forecast Confidence & Scenarios:

The Storm Prediction Center has issued a Marginal Risk (5% chance
for severe wind gusts of 58 mph or greater) across southern
Judith Basin and Fergus Counties this afternoon. Saturday there is
a 15 - 35% chance for thunderstorms in Southwestern Montana and
along the Hi-Line. On Sunday and Monday there is a 10 - 25% chance
for thunderstorms across North-central, Central, and Southwestern
Montana. On Tuesday there is a 15 - 40% chance for thunderstorms
across North-central, Central, and Southwestern Montana. On
Wednesday there is a 25 - 50% chance for thunderstorms across
North-central, Central, and Southwestern Montana.

On Monday there is a 20 - 50% chance for a high of 90 degrees or
greater across North-central Montana, the Helena Valley, and the
Gallatin Valley. On Tuesday there is a 50 - 80% chance for a high of
90 degrees or greater across North-central Montana, the Helena
Valley, and the Gallatin Valley. -IG


&&

.AVIATION...
28/06Z TAF Period

A passing shortwave within a westerly flow aloft will bring variable
mid- and higher level cloudiness and west to northwesterly breezes
tonight into Saturday. There will also be a few isolated showers and
thunderstorms, mostly between 28/20 and 29/05Z. With mid- to high
level cloud bases and shower and thunderstorms activity looking to
be far more isolated than previous days, VFR conditions are
generally expected to prevail for the duration of the TAF period.
- RCG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  52  78  48  80 /   0   0   0   0
CTB  47  72  47  77 /   0  20   0   0
HLN  52  78  50  81 /   0   0   0   0
BZN  49  82  46  81 /  20   0   0   0
WYS  39  76  37  75 /  20  10   0   0
DLN  46  79  44  79 /   0   0   0   0
HVR  53  80  50  80 /   0  10  10   0
LWT  50  74  47  74 /  20   0   0   0

&&

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

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