textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Considerable showers continue with mountain snow above 6,500 feet late tonight into early Monday, mainly through central Idaho and northwest Montana.

- Drying and warming conditions by mid-week.

- Trending wetter late Thursday into Friday.

An upper low moving through eastern Washington will track into northwest Montana tonight, continuing to bring periodic showers, isolated thunderstorms, and gusty southwest winds across much of the Northern Rockies.

The heaviest precipitation will target north-central Idaho and northwest Montana, where mountain locations could receive up to an inch of total precipitation, with lighter amounts in the valleys. Snow levels will fall near 6,500 feet tonight, bringing light snow accumulations along the Continental Divide southward to the Bitterroots. These cold, raw conditions will create a heightened hypothermia risk for backcountry recreationists. Farther south and east, including Missoula, rainfall will remain light and spotty. In contrast, southwest Montana will stay mostly dry with strong, gusty winds, driving critical fire weather conditions through this evening (Red Flag Warning).

The system exits by Tuesday morning, clearing the way for a briefly warmer and drier pattern through mid-week, though shower chances linger near the Canadian border. Clearing skies early Tuesday will bring chilly temperatures to areas along and south of I-90. Sub- freezing temperatures are anticipated in the higher valleys of southwest Montana and along the Divide, while frost will likely impact the typical colder locations in the Missoula, Bitterroot, and Clearwater valleys.

A trend in the ensemble guidance points toward another upper- level low cutting off along the Pacific coast Wednesday night before drifting across western Montana and north-central Idaho Thursday into Friday. A monsoonal moisture tap appears to be interacting with the low causing precipitation chances to trend upward late in the week. Approximately 60 percent of ensemble solutions support this wetter scenario, though overall confidence in exact timing and local details remain low.

AVIATION

Scattered showers and isolated thunderstorms will continue across the Northern Rockies this afternoon, with coverage tapering off south across southwest Montana and Lemhi County. Heavier convective cells will briefly degrade ceilings and visibilities to MVFR, accompanied by localized mountain obscurations. Southwest surface winds will gust 20-25 kts through early evening, creating localized mechanical turbulence.

Wrap-around moisture associated with a passing upper-level low will maintain widespread light precipitation tonight into Monday morning across north-central Idaho and northwest Montana, becoming increasingly terrain-forced farther south. Widespread mountain obscurations will persist well into Monday morning alongside gusty westerly winds of 15-25 kts late Monday morning and afternoon.

MSO WATCHES/WARNINGS/ADVISORIES

MT...Red Flag Warning until 9 PM MDT this evening for East Beaverhead.

ID...None.