textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Cool, breezy, and showery today.

- Localized frost Thursday morning, mainly south of the I-90 corridor.

- Breezy with scattered showers Friday-Saturday, focused on western Montana (Glacier Region) while Idaho stays dry.

- Warm up early next week.

Today through Thursday Morning: Periodic showers will continue today under a moist northwest flow. Expect shower coverage to increase by late morning as a disturbance drops into the Northern Rockies and combines with daytime heating-induced instability. Breezy conditions will return by mid to late morning, with widespread gusts of 20 to 30 mph and localized gusts up to 45 mph near stronger showers. High- resolution guidance limits the thunderstorm potential to a slight chance (under 20%), primarily focused from north-central Idaho southeastward into southwest Montana.

Daytime temperatures will remain roughly 15 degrees below normal. Morning snow levels will range from 5,000 to 5,500 feet, bringing a few inches of accumulation to the higher terrain. Backcountry recreationists should prepare for winter-like conditions and an elevated risk of hypothermia. Showers and winds will gradually diminish after sunset, leading to partial clearing overnight.

Localized valley frost is possible Thursday morning, primarily south of the I-90 corridor. The National Blend of Models (NBM) indicates a 30 to 40% probability of temperatures dropping below 35F in the Bitterroot Valley, roughly 70% in Salmon, and 40 to 50% for the higher valleys along the Continental Divide. The primary caveat to this frost potential is residual cloud cover, as uncertainty remains regarding how quickly skies will clear within the moist northwest flow. A warming and drying trend takes hold later Thursday, bringing mostly sunny skies and a return to seasonal temperatures.

Friday through Early Next Week: The next weather system arrives Friday afternoon and lingers through the weekend as a weak cold front and upper-level disturbance settle south. While temperatures will only cool slightly, shower chances return, primarily across western Montana, while north-central Idaho remains generally dry. The most widespread showers and isolated thunderstorms will focus over the Glacier Region. Rainfall amounts appear light, with NBM means generally under 0.10 inches in the valleys, though up to 0.50 inches is possible across the higher terrain of Glacier. Breezy conditions will persist, with afternoon gusts reaching 20 to 25 mph each day.

Looking into early next week, ensemble clusters strongly favor an unseasonably strong high pressure ridge building along the West Coast. This pattern will bring dry conditions and a significant warming trend, with temperatures climbing into the lower 80s for western Montana valleys and the lower 90s in north-central Idaho. The only exception to the dry weather will be a few isolated showers along the Continental Divide.

AVIATION

Moist northwest flow will maintain periodic showers today, with coverage increasing by late morning as an upper-level shortwave moves through. While VFR conditions will generally prevail, brief MVFR ceiling and visibility reductions and mountain obscurations are possible within heavier showers. Widespread westerly wind gusts of 20-25 kt will develop by late morning, with localized gusts up to 40 kt possible near stronger convective showers. A slight chance (<20%) of thunderstorms exists this afternoon, primarily from north-central Idaho southeastward into southwest Montana. Showers and winds will diminish after sunset with partial clearing overnight. Patchy valley fog may develop early this morning near KSMN, with localized valley fog potential across north-central Idaho and northwest Montana Thursday morning.

MSO WATCHES/WARNINGS/ADVISORIES

MT...None. ID...None.