Flash Flood Warning 1, NWS Missoula, MT

716 
WGUS75 KMSO 180039
FFSMSO

Flash Flood Statement
National Weather Service Missoula MT
639 PM MDT Fri Jul 17 2026

MTC039-180049-
/O.CAN.KMSO.FF.W.0001.000000T0000Z-260718T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Granite MT-
639 PM MDT Fri Jul 17 2026

...FLASH FLOOD WARNING IS CANCELLED FOR CENTRAL GRANITE COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please continue to heed remaining road closures.

A Flood Watch remains in effect until 900 PM MDT for a portion of
west central Montana.

&&

LAT...LON 4638 11345 4633 11347 4632 11337 4638 11331
      4642 11341

$$

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
259 PM MDT Fri Jul 17 2026

MTZ007-172130-
Butte/Blackfoot Region MT-
259 PM MDT Fri Jul 17 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTH CENTRAL DEER LODGE...
SOUTHERN POWELL AND SOUTHEASTERN GRANITE COUNTIES UNTIL 330 PM MDT...

At 259 PM MDT, Doppler radar was tracking a strong thunderstorm 8
miles west of West Valley, or 10 miles west of Anaconda, moving
northeast at 10 mph.

HAZARD...Wind gusts up to 30 mph and half inch size hail.

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...
  Anaconda, West Valley, Georgetown and Lost Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4605 11314 4616 11335 4637 11313 4620 11283
TIME...MOT...LOC 2059Z 221DEG 8KT 4614 11318

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...30 MPH

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

MTZ007-172145-
Butte/Blackfoot Region MT-
318 PM MDT Fri Jul 17 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTH CENTRAL POWELL AND
NORTHEASTERN GRANITE COUNTIES UNTIL 345 PM MDT...

At 318 PM MDT, Doppler radar was tracking a strong thunderstorm 10
miles southeast of Drummond, moving north at 15 mph.

HAZARD...Wind gusts up to 30 mph and penny size hail.

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...
  Drummond, Jens, Goldcreek, New Chicago, Hall, Brock Creek and
  Maxville.

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 4641 11299 4647 11326 4678 11313 4669 11277
TIME...MOT...LOC 2117Z 200DEG 11KT 4653 11306

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

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

MTZ006-043-172145-
Potomac/Seeley Lake Region MT-Bitterroot/Sapphire Mountains MT-
319 PM MDT Fri Jul 17 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN MISSOULA AND NORTH
CENTRAL GRANITE COUNTIES UNTIL 345 PM MDT...

At 319 PM MDT, Doppler radar was tracking a strong thunderstorm 16
miles west of Drummond, moving north at 10 mph.

HAZARD...Wind gusts up to 30 mph and penny size hail.

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...
  Nimrod.

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 4662 11363 4681 11358 4676 11333 4665 11339
      4659 11338 4657 11337
TIME...MOT...LOC 2119Z 195DEG 9KT 4664 11348

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

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