Hydrologic Outlook

Hydrologic Outlook
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

Hydrologic Outlook
IDC061-079-090445-

Hydrologic Outlook
National Weather Service Spokane WA
842 PM PST Sun Dec 7 2025

...RIVER RISES AND INCREASED RISK FOR MUD AND ROCK SLIDES THIS
WEEK...

A series of warm, wet, and breezy weather will bring periods of high
mountain snow and heavy rain to low to middle elevation areas of the
central and southern Idaho Panhandle mountains Monday through
Wednesday. Snow levels will fluctuate between 5000 and 7000 feet.
Lower elevation snowmelt in addition to the rain will lead to rises
on
small creeks and streams. This will also bring an increased risk for
mud and rock slides in areas of steep and susceptible terrain.
$$

OTX