Severe Thunderstorm Warning 12, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
139 PM MDT Fri Jul 17 2026

.DISCUSSION...

KEY MESSAGES:

- Strong to severe thunderstorms this afternoon and evening,
  bringing the threat of strong winds, large hail, and heavy rain.

- Trending drier and breezy this weekend. Elevated fire weather by
  Sunday from hot, dry, and breezy conditions, especially in
  northwest Montana

- Thunderstorms return by Tuesday next week with the next Monsoon
  moisture surge.

Monsoonal moisture has peaked over the region, with atmospheric
moisture content running at 200 percent of normal and precipitable
water values over 1 inch. Impressive instability along with an
incoming wave of energy currently moving through central Idaho
sets the stage for widespread thunderstorm development this
afternoon. High resolution models show convection forming over the
southern Bitterroot mountains around 2 to 3pm, moving northwards
and potentially forming into a line of storms that could hold
together into northwest Montana this evening. Gusty winds will be
the main concern with this convection, with gusts 40 to 50 mph
anticipated with stronger storms. It should be noted that a few
of our high resolution models are showing the potential for gusts
over 60 mph through the Missoula valley northwards into the
Mission valley early this evening. While not a likely scenario (10
to 20 percent chance) it is something that will be monitored
closely moving forwards. Further north, in northwest Montana, hail
becomes more of a concern due to increased shear values. It
should also be noted that thunderstorms could linger across
northwest Montana through early Saturday morning.

Storms will also be capable of very heavy rainfall rates of 0.75"
or more per hour. fortunately storm motion should keep cells
moving fairly rapidly which overall decreases the flash flooding
risk. However, sensitive flood prone areas and recent burn scars,
particularly in Lemhi County and southwest Montana, could have
flood concerns if they take a direct hit from thunderstorms.

On Saturday, the low pressure system that has been sitting off the
Pacific Northwest coast slowly moves through southern British
Columbia and Alberta, flattening the ridge of high pressure and
bringing more westerly flow aloft. This will shift thunderstorm
potential primarily to locations south of Interstate 90. Never
the less, a few storms still could become strong in these areas
with gusty winds, and brief heavy rain the main threats. Further
north across northwest Montana, breezy westerly winds will
develop. This coupled with much drier air could enhance fire
weather concerns. By Sunday, much drier air moves over all of
western Montana and north central Idaho, with hot, dry and breezy
conditions anticipated.

Global ensembles suggest the next surge of monsoon moisture will
arrive by the middle of next week (Tuesday into Thursday). Chances
for showers and thunderstorms will trend higher each day as
precipitable water values reach over one inch.

&&

.AVIATION...The atmosphere over the Northern Rockies airspace is
unstable and thunderstorms have begun to develop. Any thunderstorm
will be capable of gusty outflow winds 40 to 50 mph, but this
threat is higher probability at KMSO and KHRF between 17/2200 and
18/0200z. Additionally, hail 0.25 to 1.00" is possible at all
terminals along with brief but heavy rainfall degrading
visibility 2-4 statute miles. Thunderstorm threat decreases after
18/0300z but showers and embedded thunderstorms will remain a
threat in northwest MT overnight.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...&&

Special Weather Statement
National Weather Service Missoula MT
354 PM MDT Fri Jul 17 2026

MTZ005-172230-
Missoula/Bitterroot Valleys MT-
354 PM MDT Fri Jul 17 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTH CENTRAL RAVALLI COUNTY
UNTIL 430 PM MDT...

At 354 PM MDT, Doppler radar was tracking a strong thunderstorm over
Victor, or 10 miles north of Hamilton, moving north at 10 mph.

HAZARD...Wind gusts up to 30 mph and penny size hail. Heavy rainfall
         0.50 to 0.75" per hour possible.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
  Stevensville, Victor, Pinesdale and Bell Crossing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

Heavy rainfall is also occurring with this storm and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4632 11402 4634 11424 4643 11424 4647 11422
      4651 11419 4658 11416 4657 11396
TIME...MOT...LOC 2153Z 184DEG 8KT 4638 11413

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...30 MPH

Preliminary Local Storm Report
National Weather Service Missoula MT
401 PM MDT Fri Jul 17 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0330 PM     Rain             5 WNW West Valley       46.19N 113.12W
07/17/2026  M1.29 Inch       Deer Lodge         MT   Trained Spotter

            Spotter reported lots of hail, with a few up
            to 1 inch.

&&

BEC

Special Weather Statement
National Weather Service Missoula MT
408 PM MDT Fri Jul 17 2026

MTZ007-172230-
Butte/Blackfoot Region MT-
408 PM MDT Fri Jul 17 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN DEER LODGE...
NORTHERN SILVER BOW AND SOUTH CENTRAL POWELL COUNTIES UNTIL 430 PM
MDT...

At 408 PM MDT, Doppler radar was tracking a strong thunderstorm near
Galen, or 7 miles south of Deer Lodge, moving northeast at 20 mph.

HAZARD...Wind gusts up to 30 mph and nickel size hail. Heavy rain
         rates 0.50 to 0.75 inches per hour are possible.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
  Deer Lodge, Galen and Racetrack.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

Torrential rainfall is also occurring with this storm and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4620 11284 4628 11294 4649 11270 4634 11245
      4633 11245 4633 11247 4634 11247 4634 11249
      4633 11250 4633 11253 4631 11256 4630 11257
      4628 11256 4626 11256 4624 11258 4624 11260
      4621 11257 4620 11258 4618 11257 4617 11258
TIME...MOT...LOC 2208Z 237DEG 15KT 4629 11278

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...30 MPH

Preliminary Local Storm Report
National Weather Service Missoula MT
428 PM MDT Fri Jul 17 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0328 PM     Hail             5 WNW West Valley       46.18N 113.11W
07/17/2026  M1.00 Inch       Deer Lodge         MT   Trained Spotter

            Heavy rain of 1.29 inch in less than an
            hour.

&&

BEC

Special Weather Statement
National Weather Service Missoula MT
451 PM MDT Fri Jul 17 2026

MTZ007-043-172315-
Potomac/Seeley Lake Region MT-Butte/Blackfoot Region MT-
451 PM MDT Fri Jul 17 2026

...A STRONG THUNDERSTORM WILL IMPACT WEST CENTRAL POWELL AND EAST
CENTRAL MISSOULA COUNTIES UNTIL 515 PM MDT...

At 451 PM MDT, Doppler radar was tracking a strong thunderstorm 8
miles west of Ovando, or 26 miles north of Drummond, moving northeast
at 20 mph.

HAZARD...Wind gusts up to 30 mph and penny size hail. Rainfall rates
         of 0.50 to 0.75 inches are possible.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
  Ovando, Woodworth and Clearwater.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

Torrential rainfall is also occurring with this storm and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4690 11335 4701 11353 4723 11331 4709 11304
TIME...MOT...LOC 2250Z 216DEG 15KT 4702 11333

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...30 MPH

Preliminary Local Storm Report
National Weather Service Missoula MT
503 PM MDT Fri Jul 17 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0502 PM     Flash Flood      1 SE Drummond           46.66N 113.13W
07/17/2026                   Granite            MT   Emergency Mngr

            Flooding across I-90 WB lane between mile
            marker 155-156, east of Drummond MT.

&&

BEC