Severe Thunderstorm Warning 110, NWS Great Falls, MT

Area Forecast Discussion
National Weather Service Great Falls MT
200 PM MDT Wed Sep 2 2026

.KEY MESSAGES...

 - It will be windy across North-central, Central, and
   Southwestern Montana this afternoon through Friday.

 - Severe thunderstorms will continue through this evening with
   wind gusts in excess of 60 mph.

 - It will cool off through this weekend with showers and
   thunderstorms Friday through Sunday.

&&

.DISCUSSION...

 - Meteorological Overview:

This afternoon there is an an upper-level trough moving over North-
central, Central, and Southwestern Montana. This will allow
temperatures to cool down slightly with showers and thunderstorms
across the area. Due to strong southerly flow aloft and strong low-
level winds it will be windy across North-central, Central, and
Southwestern Montana on Wednesday with the strongest winds along the
Rocky Mountain Front and in north-south orientated valleys. On
Thursday the upper-level trough remains over North-central, Central,
and Southwestern Montana. This combined with strong southerly flow
aloft and strong low-level winds will bring another day of windy
conditions to the area. On Thursday it will be mostly dry.

On Friday a closed upper-level low is over Washington and Oregon
with southwest flow over North-central, Central, and Southwestern
Montana. This will allow temperatures to be around seasonal
averages with another day of showers and thunderstorms and breezy
conditions. On Saturday and Sunday the closed upper-level low
remains over Washington and Oregon with southwest flow over North-
central, Central, and Southwestern Montana. This will bring
another day with about seasonal averages for temperatures and
showers and thunderstorms around each day this weekend. -IG

 - Forecast Confidence & Scenarios:

On Thursday there is a 40 - 60% chance for wind gusts of 45 mph or
greater across Southwestern Montana. On Thursday there is a 30 - 60%
chance for wind gusts of 35 mph or greater across North-central
Montana. On Friday there is a 40 - 80% chance for wind gusts of 30
mph or greater across North-central, Central, and Southwestern
Montana with the greatest probability in Southwestern Montana.

Today the Storm Prediction Center (SPC) issued a slight risk (15%
chance for wind gusts of 58 mph or greater within 25 miles of a
point) for severe thunderstorms for most of North-central Montana.
Today the SPC issued a marginal risk (5% chance for wind gusts of
58 mph or greater within 25 miles of a point) across most of the
rest of Central and Southwestern Montana. On Saturday there is a
15 - 30% chance for thunderstorms across Central and Southwestern
Montana. On Sunday there is a 15 - 30% chance for thunderstorms
across North-central, Central, and Southwestern Montana. -IG

Fire Weather: Medium Confidence (50%) in critical conditions on
today and Thursday. Winds are the highest source of confidence,
humidity is our lowest with values borderline. However, deep
mixing advertised by the models does support values approaching
critical values.

Extended Regime: Low Confidence (30%) in the overall changes in the
upper-level pattern. Cut off lows are notoriously difficult to pin
point in the long range as are the resulting impacts. -JR

&&

.AVIATION...
02/18Z TAF Period

VFR conditions will prevail at all terminals during this TAF
Period outside of during any thunderstorms. During the beginning
of this TAF Period thunderstorms will affect the KHLN, KGTF, KCTB,
and KHVR terminals. During any thunderstorms there will be gusty,
erratic winds, lightning, and a brief heavy downpour. The heavy
downpour could briefly cause mountain obscuration and a reduction
in visibility to MVFR-levels. Isolated thunderstorms will produce
wind gusts in excess of 50 kts. Isolated thunderstorms have a low
chance to kick up enough dust to reduce visibility to MVFR-levels
or lower. During the duration of this TAF Period there will be
isolated instances of low-level wind shear. At the KEKS terminal
for the first 9 hours of this TAF Period there will be sustained
winds in excess of 30 kts. During this TAF Period smoke from
wildfires will reduce slantwise visibility across all terminals.
-IG

For KGTF: Winds will quickly pick up out of the south/southwest
this afternoon. There is a 20% chance for exceeding a 15kt
crosswind between 02/18Z and 02/21Z. Between 21Z and 23Z a line
of thunderstorms will approach KGTF. The thunderstorms will
produce wind gusts in excess of 50 kts with a low chance for a
wind gust exceeding 60 kts. Additionally there is an expected wind
shift with this line from a more south/southwest direction to the
west behind the line of thunderstorms. Gusty winds will continue
through at least 03/04Z before slowly tapering off as the night
continues. The threat for crosswinds will be low but the headwinds
may be above 15kts through at least 03/03Z. -thor/IG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  50  76  49  74 /  10   0  10  10
CTB  46  66  45  66 /  50   0  30  10
HLN  46  75  47  74 /  10   0  10  30
BZN  47  76  45  79 /   0   0   0   0
WYS  33  64  36  68 /   0   0   0   0
DLN  42  72  41  74 /  10   0  10  20
HVR  50  80  51  81 /  50   0   0   0
LWT  49  77  52  80 /  20   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 9 PM MDT this evening for Madison River
Valley.

High Wind Watch from 9 PM MDT this evening through Thursday
evening for Madison River Valley.

&&

http://www.weather.gov/greatfalls

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