Helena Valley Northeast, Montana 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

642
FXUS65 KTFX 121711
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1111 AM MDT Tue Aug 12 2025

Aviation Section Updated.

.KEY MESSAGES...

 - Temperatures will warm up today and Wednesday with a brief cool
   down on Thursday before warming up for the weekend.

 - There will be isolated showers and thunderstorms today and
   Wednesday in Southwestern Montana.

 - It will be windy Wednesday through Friday across Southwestern Montana
   and along the Rocky Mountain Front and adjacent plains.

&&

.UPDATE...
/Issued 932 AM MDT Tue Aug 12 2025/

Satellite imagery shows mainly clear skies across the area this
morning with some scattered mid level clouds in northwest flow
aloft moving across eastern portions of north-central MT. A
subtle emebedded disturbance in the NW flow may trigger some
isolated hi-based thunderstorms this afternoon across primarily SW
MT, where the main risk will be gusty winds. Hoenisch

&&

.DISCUSSION...
/Issued 932 AM MDT Tue Aug 12 2025/

 - Meteorological Overview:

Today there is an upper-level ridge over North-central, Central, and
Southwestern Montana with southwest flow aloft. This will bring
showers and thunderstorms to Southwestern Montana today with
temperatures warming up some more. This afternoon showers and
thunderstorms will primarily be confined to Gallatin and Madison
Counties. On Wednesday an upper-level trough begins to move over the
area. Wednesday evening a surface cold front will move south from
Canada through the area. This combined with the upper-level trough
will bring showers and thunderstorms to Southwestern Montana
Wednesday afternoon and evening. Due to strong upper-level flow
combined with a strong surface pressure gradient it will be windy on
Wednesday across Southwestern Montana and along the Rocky Mountain
Front and adjacent plains.

On Thursday the upper-level trough remains over North-central,
Central, and Southwestern Montana. This combined with the cold
frontal passage will cool temperatures down with mostly dry weather.
On Thursday due to a strong surface pressure gradient combined with
strong mid-level flow it will be windy with the strongest winds in
Southwestern Montana and along the Rocky Mountain Front and adjacent
plains. On Friday an upper-level ridge builds back in over North-
central, Central, and Southwestern Montana. This will warm the area
back up. On Friday due to a strong surface pressure gradient
combined with strong mid-level flow it will be windy with the
strongest winds in Southwestern Montana and along the Rocky Mountain
Front and adjacent plains. On Saturday the upper-level ridge remains
over North-central, Central, and Southwestern Montana. This will
allow temperatures to warm up a few more degrees on Saturday with
mostly dry weather. On Sunday a quick moving shortwave moves through
the upper-level flow and then an upper-level ridge builds in over
North-central, Central, and Southwestern Montana. This will allow
the mostly dry and warm weather to continue. On Monday the upper-
level ridge remains over North-central, Central, and Southwestern
Montana which will allow temperatures to warm up further with dry
weather.

 - Forecast Confidence & Scenarios:

Today and Wednesday there is a 15 - 30% chance for thunderstorms
across North-central, Central, and Southwestern Montana with the
greatest chance for thunderstorms in the West Yellowstone area each
day. On Thursday there is a 15 - 30% chance for thunderstorms in
Southwestern Montana.

On Wednesday and Thursday there is a 40 - 70% chance for wind gusts
of 40 mph or greater across Southwestern Montana. On Wednesday there
is a 50 - 80% chance for wind gusts of 45 mph or greater along the
Rocky Mountain Front and adjacent plains. On Friday there is a 30 -
60% chance for wind gusts of 40 mph or greater across Southwestern
Montana and along the Rocky Mountain Front and adjacent plains.

Today there is greater than a 70% chance for high temperatures of 90
degrees or greater across most of the lower-elevations of North-
central, Central, and Southwestern Montana south of the Hi-Line. On
Wednesday across the lower-elevations of North-central, Central, and
Southwestern Montana there is greater than a 90% chance for high
temperatures of 90 degrees or greater. On Wednesday there is a 50 -
70% chance for high temperatures of 95 degrees or greater across
most of the North-central plains east of I-15. -IG


&&

.AVIATION...
12/18Z TAF Period

This afternoon, isolated showers and thunderstorms are expected to
develop in Southwest MT along and south of the I-90 corridor.
Gusty winds will be possible with any shower or thunderstorm.
Other than that, you can expect a few mid level clouds over North-
Central MT through the TAF period. -Wilson

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

&&

.FIRE WEATHER...

It will hot and dry over the area the next two days. It will be
windy today with winds increasing tomorrow. This will lead to
elevated fire weather conditions for grassy areas. A fire weather
watch was issued for portions of Southwest Montana for these
conditions on Wednesday. -IG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  91  60  95  54 /   0  10   0   0
CTB  86  56  89  50 /  10  10   0  10
HLN  92  60  94  57 /   0  10   0   0
BZN  92  55  95  52 /  10  10  10   0
WYS  83  43  86  41 /  10  10  20  10
DLN  89  52  90  49 /  10  10  10   0
HVR  87  58  96  54 /  10  10   0   0
LWT  85  58  91  54 /  10  10   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
&&

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