Special Weather Statement, NWS Missoula, MT

Area Forecast Discussion
National Weather Service Missoula MT
157 PM MDT Thu May 28 2026

.DISCUSSION...

KEY MESSAGES:

- Warm temperatures and showers/thunderstorms with a few strong
  storms this afternoon, especially across northwest Montana and
  through north central Idaho

- Prolonged heavy rainfall this weekend in western Montana,
  elevating risks for hydrologic responses and rockfalls
  especially near and along the Continental Divide.

- High elevation snowfall on Saturday night into Monday could
  create difficult backcountry conditions.

This Afternoon/Evening:

This afternoon will bring the warmest temperatures of the week,
with valley highs climbing into the upper 80s to near 90 degrees
across western Montana and north-central Idaho. Similar to
yesterday, thunderstorms will develop by early afternoon and track
northwestward. Activity will focus primarily from the Bitterroot
Valley northward and across north-central Idaho, including the
Camas Prairie. A few stronger storms could produce erratic wind
gusts, brief heavy downpours, and small hail. Meanwhile, elevated
fire weather concerns persist across southwest Montana this
afternoon, particularly south of Dillon due to gusty winds and
relative humidity dropping into the teens.

Friday:

The weather pattern shifts significantly on Friday as an incoming
Pacific low-pressure system brings a band of heavy rain. South to
north moving showers and storms will bring localized heavy rain
and the potential for gusty winds and hail once again. Storms may
train over parts of the region particularly the US-12 and US-95
corridors in Idaho, thus localized flash flooding is a concern.

Saturday through Monday:

By Saturday, the low-pressure system is projected to settle near
the Yellowstone region, placing western Montana within a robust
deformation zone. Tapping into anomalous moisture, this setup
will trigger a prolonged, highly efficient rainfall event into at
least Monday.

- Hydrologic & Terrain Impacts: Saturated soils from recent rains
  combined with ongoing high-elevation snowmelt will elevate the
  risk for significant rises on rivers and streams, as well as
  rockfalls in steep canyon terrain.

- Precipitation Totals: The heaviest totals are forecast near the
  Continental Divide, where there is a 70 to 90 percent chance of
  exceeding 1 inch of rain, with localized amounts of 2 to 4
  inches possible.

- Snow Levels & Backcountry: Sharp cooling aloft will cause snow
  levels to drop to around 6,000 feet along the Continental Divide
  by Sunday morning. Backcountry users should prepare for raw,
  winter-like conditions and difficult travel.

Extended Outlook:

Looking further ahead, ensemble clusters favor a quick transition
back to building high pressure and above- normal temperatures by
mid-next week, offering a reprieve from this weekend's wet
pattern.

&&

.AVIATION...VFR conditions will prevail across western Montana and
north-central Idaho terminals this afternoon, though valley
temperatures approaching 90F will contribute to elevated density
altitude. Scattered afternoon and evening thunderstorms will focus
from the Bitterroot Valley northward and across north-central
Idaho, with high-resolution models maintaining coverage trends
similar to yesterday. Any developing convective cells could
produce short- lived, localized MVFR/IFR conditions due to heavy
downpours and low ceilings, alongside erratic outflow wind gusts,
hail, and mountain obscurations. Outside of convective activity,
terminals in southwest Montana and Lemhi County (including KBTM
and KSMN) will experience breezy southeasterly surface winds this
afternoon. Patchy fog and low stratus may develop Friday morning
in areas that receive rain this evening, ahead of another
widespread round of showers and thunderstorms Friday afternoon.

&&

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

Special Weather Statement
National Weather Service Missoula MT
330 PM MDT Thu May 28 2026

MTZ007-043-282200-
Butte/Blackfoot Region MT-Potomac/Seeley Lake Region MT-
330 PM MDT Thu May 28 2026

...A STRONG THUNDERSTORM WILL IMPACT WEST CENTRAL POWELL AND EAST
CENTRAL MISSOULA COUNTIES UNTIL 4 PM MDT...

At 330 PM MDT, Doppler radar was tracking a strong thunderstorm 12
miles north of Drummond, moving northwest at 20 mph.

HAZARD...Wind gusts up to 40 mph and pea 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...
  Ovando and Greenough.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4685 11330 4692 11345 4708 11321 4685 11298
      4676 11311
TIME...MOT...LOC 2129Z 136DEG 17KT 4684 11310

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

Special Weather Statement
National Weather Service Missoula MT
354 PM MDT Thu May 28 2026

IDZ008-282230-
Lower Hells Canyon/Salmon River Region ID-
254 PM PDT Thu May 28 2026

...A STRONG THUNDERSTORM WILL IMPACT WEST CENTRAL IDAHO COUNTY UNTIL
330 PM PDT...

At 254 PM PDT, Doppler radar was tracking a strong thunderstorm 10
miles north of Riggins, or 26 miles south of Grangeville, moving
northwest at 20 mph.

HAZARD...Wind gusts up to 40 mph and pea 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...
  Lucile and Slate Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4546 11626 4552 11654 4555 11653 4556 11651
      4558 11648 4559 11648 4560 11646 4561 11646
      4565 11649 4568 11653 4570 11654 4573 11654
      4575 11655 4578 11659 4579 11658 4566 11623
TIME...MOT...LOC 2154Z 115DEG 19KT 4556 11631

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH