368
FXUS65 KTFX 121115
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
515 AM MDT Tue May 12 2026

Aviation Section Updated.

.KEY MESSAGES...

- Another warm and dry day today across the region.

- Hot, breezy to gusty winds, and showers and thunderstorms return
  Wednesday.

- Daily chances for precipitation and breezy to windy conditions
  continue through the weekend.

&&

.DISCUSSION...
/Issued 1212 AM MDT Tue May 12 2026/

 - Meteorological Overview:

Brief upper-level ridging continues today, which will bring another
day of dry conditions. Temperatures will also be well above normal
today, with upper 70s to mid 80s forecasted across lower
elevations. There is a low end chance for a few showers in
Beaverhead County this afternoon.

Southwest flow aloft increases late Tuesday into Wednesday as a
closed low moves onshore across the Western U.S. This southwest
flow advects in warm, moist air across the region. Temperatures
will be the hottest on Wednesday, where current afternoon
temperatures are forecasted to reach the upper 80s to low 90s for
most of the region. Increasing southwest winds ahead of the main
trough will bring breezy to gusty winds, especially across
Southwest MT. Strong vertical daytime mixing will help lower
relative humidities, bringing a concern for fire weather in
Southwest MT and the Hi-line.

Decent mid to high level moisture helps develop showers and
thunderstorms across the state of Montana Wednesday afternoon and
evening. Forecast soundings show deep inverted V soundings due to
the very dry surface layer. This combined with decent mid level
winds results in strong to severe wind gusts being the main hazard
with showers and thunderstorms. The best potential for strong to
severe storms will be Southwest MT through North-Central MT south of
the Highway 2 corridor.

Models start to diverge slightly heading into Thursday on the
track and speed of this upper-close low/trough moving through
Montana. This will mainly impact timing of gusty winds moving into
the region, as well as precipitation track. Both the Euro and GFS
models hint at a strong 700mb jet forming across North-Central
MT as this trough axis moves through, which will bring breezy to
gusty winds across the area throughout the day Thursday.

Friday through the weekend, westerly flow aloft looks to be
persistent. A few shortwaves move through during this time frame,
which will continue daily chances for precipitation. Decent cross-
barrier flow also helps keep breezy to gusty conditions mainly
across North-Central MT during this time frame. Temperatures cool
back to near to slightly below averages. Snow levels falling
Thursday through the weekend indicate light snow may reach the
mountains/passes, but recent warm temperatures will make any snow
struggle to accumulate.

 - Forecast Confidence & Scenarios:

Thunderstorm Risk Wednesday:

Models are showing modest CAPE of up to 1,000 j/kg across Southwest
and North-Central MT (with the highest corridor being in North-
Central MT). Strong daytime vertical mixing will create a very dry
surface layer, resulting in deep inverted V forecast sounding
profiles. Strong to severe wind gusts will be the primary concern
with showers and thunderstorms. One thing to watch for, is how much
cloud cover there is in the morning. This will affect how much
daytime heating occurs, and can limit instability development and
strong daytime vertical mixing. However, with strong synoptic
winds already in the area, this might be able to overcome this
limitation. Southwest winds aloft increases throughout the day
across Southwest. Any stronger shower/thunderstorm will help mix
these winds down to the surface. Although the 700mb jet increases
throughout the day Wednesday across Southwest MT, most of the high
wind gusts look to be mainly convective driven. Therefore, high
wind watches have been held off for now.


Winds late Wednesday Night Into Thursday:

As this main shortwave moves through the region, stronger 700mb
winds move in behind across North-Central MT. Both the GFS and
European models hint at peak winds happening very early Thursday
through the morning hours. Although this isn`t the best timing
for mixing winds down to the surface, both of these models to try
to mix down some of these winds down. By the afternoon the mid
level jet still peaks to 40-50kts, especially closer to
Blaine/Fergus Counties. Therefore, strong winds look to continue
through the day Thursday. Timing of these winds are still a little
uncertain, but the signal has been more consistent the past few
models runs to give enough confidence for issuing High Wind
Watches along the Rocky Mountain Front and North-Central MT.
-Wilson

&&

.AVIATION...
12/12Z TAF Period

Ridging aloft moves in and brings widespread VFR conditions for the
duration of the TAF period; however, high level clouds will be on
the increase, especially after 13/00Z. There may also be a few
cloud builds or even an isolated shower or storm over the higher
terrain of far SW MT after 13/00Z. Winds will become easterly over
the plains and light and variable over the southwest. - RCG

&&

.FIRE WEATHER...

Elevated to near-critical fire weather conditions are expected on
Wednesday as temperatures soar well above normal and into the mid-
80s to low 90s, with the potential for numerous locations to set new
daily record highs for May 13th across Southwest through North
Central Montana. The warm temperatures will be accompanied by strong
and gusty south to west winds; most notably along and south of the I-
90 corridor within the north-south orientated valleys of Southwest
Montana, west of the I-15 corridor over the plains of Central and
North Central Montana, and across Hill and Blaine Counties. Further
enhancement of winds are likely beneath and/or near shower and
thunderstorm activity, especially across Southwest and portions of
Central Montana or generally along and south of the US Hwy 12
corridor. Dry conditions, with relative humidity values in the teens
will be common across much of the plains and valleys. Probabilities
for the Hot-Dry-Windy Index (HDWI) rising to within the 95Pct of
Climatology has increased to a 60% or greater chance across most
lower elevations across Southwest Montana south of the I-90 and
across Hill and Blaine Counties in North Central Montana, with Fire
Weather partners indicating that fuels would be receptive to fire,
especially across Southwest Montana. -Moldan

The current fire weather watches for FWZ113 and Southwest MT
remains on track for Wednesday. -Wilson

&&

.CLIMATE...

...RECORD OR NEAR RECORD MAXIMUM TEMPERATURES FORECAST FOR MAY 12...

LOCATION             FORECAST HIGH       RECORD HIGH
Boulder                  80                 84
Dillon                   86                 84
West Yellowstone         80                 79


...RECORD OR NEAR RECORD MAXIMUM TEMPERATURES FORECAST FOR MAY 13...

LOCATION             FORECAST HIGH       RECORD HIGH
Boulder                  82                 83
Bozeman MSU              87                 86
Chester                  86                 86
Choteau                  86                 85
Conrad                   85                 87
Cut Bank                 82                 84
Dillon                   85                 87
Fort Benton              92                 88
Great Falls              88                 89
Helena                   88                 89
Havre                    92                 92
Lewistown                87                 88
Shelby                   83                 84
Stanford                 87                 86
West Yellowstone         80                 81

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  79  50  88  48 /   0   0  30  50
CTB  76  46  82  43 /   0   0  40  50
HLN  83  49  88  46 /   0   0  40  40
BZN  81  45  88  41 /   0   0  20  60
WYS  80  42  80  34 /   0   0  20  30
DLN  84  49  83  40 /   0   0  20  30
HVR  78  47  92  45 /   0   0  10  70
LWT  74  46  87  44 /   0   0  10  60

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Watch from late Wednesday night through Thursday
evening for East Glacier Park Region-Eastern Glacier, Western
Toole, and Central Pondera-Northern High Plains-Southern High
Plains-Southern Rocky Mountain Front-Upper Blackfoot and
MacDonald Pass.

Fire Weather Watch from Wednesday afternoon through Wednesday
evening for Hill and Blaine Counties.

High Wind Watch from late Wednesday night through Thursday
evening for Bears Paw Mountains and Southern Blaine-Fergus
County below 4500ft-Hill County-Northern Blaine County-Snowy and
Judith Mountains-Western and Central Chouteau County.

High Wind Watch from late Wednesday night through Thursday
afternoon for Cascade County below 5000ft-Eastern Toole and
Liberty-Helena Valley-Judith Basin County and Judith Gap.

&&

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