979
FGUS75 KMSO 071918
ESFMSO
IDC059-MTC053-063-081-089-081930-

Hydrologic Outlook
National Weather Service Missoula MT
1218 PM MST Sun Dec 7 2025

...HEAVY PRECIPITATION TO BRING SMALL STREAM RISES, RISK FOR ROCK
AND LANDSLIDES, AND MINOR FLOODING THIS WEEK...

A prolonged atmospheric river is expected to bring periods of heavy
rain for western Montana and Lemhi County, Idaho, Monday night
through Thursday. Rising snow levels will lead to a rain on snow
event for elevations below 7,000 feet Monday night into Tuesday
morning. The precipitation rates will briefly decrease Tuesday
afternoon, before second surge of moisture arrives Tuesday night
into Thursday. During the second surge, snow levels will be lower,
ranging from 4,000-5,000 feet north of I-90, to 5,000-7,000 feet
south of I-90, with the highest snow levels across Lemhi County,
Idaho. By Thursday, significant precipitation totals are forecast,
with 1 to 3 inches in the valleys and 4 to 8 inches in the
mountains, with locally higher totals over mountain crests.
Landslides in areas of steep terrain and minor flooding in urban and
poor drainage areas is possible.  Storm drains and ditches may
become clogged with debris.
$$

AL