Hydrologic Outlook

Hydrologic Outlook
IDC035-049-059-MTC023-039-061-063-077-081-093-261700-

Hydrologic Outlook
National Weather Service Missoula MT
1147 AM MDT Mon Aug 25 2025

...Rock and mudslides due to excessive rainfall...

Where: Lemhi, Idaho, and Clearwater Counties in Idaho
       Ravalli, Mineral, Missoula, Granite, Deer Lodge, Powell, and
       Silverbow Counties in Montana

What: Confidence continues to trend higher that Monsoon moisture
will be spreading north into the Northern Rockies by Wednesday,
bringing a chance for scattered thunderstorms. These thunderstorms
will be capable of producing rain rates in excess of one half inch
per hour. The result will be the potential for rock and debris
slides in steep terrain along Forest Service roads and recent burn
scar areas, as well as Highway 95 from Riggins to Whitebird in Idaho
and Skalkaho Road in Montana.

Consider delaying any backcountry travel for Wednesday and Thursday
of this week.

$$

Hydrologic Outlook
MTC001-007-013-031-043-049-057-059-262200-

Hydrologic Outlook
National Weather Service Great Falls MT
454 PM MDT Mon Aug 25 2025

...Widespread rainfall and embedded thunderstorms expected over
Southwest and portions of Central Montana Tuesday night through
Friday...

Monsoon moisture will slowly move northward and bring periods of
widespread rain and embedded thunderstorms to Southwest and portions
of Central Montana Tuesday night through Friday. Localized heavier
downpours in excess of a half inch per hour can be expected with the
heavier cells in addition to the general four day storm totals
between a quarter to an inch and a half. The most persistent and
heaviest rainfall is expected along and south of I90 on Wednesday
and Thursday.

Impacts will mostly be limited to sensitive burn scars or other
normally flood prone locations or areas of steep terrain and may
include instances of localized flooding, debris flows, and rock
slides.

Those considering any backcountry travel for Wednesday and Thursday
of this week should be prepared for periods of excessive rainfall,
muddy roads, and potential localized flooding.
$$

RG