textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Showers and possible thunderstorms Wednesday night into Thursday for northwest Montana

- Warming for the remainder of the work week

- A weak disturbance on Saturday causing slightly cooler temperatures and potential of light showers near Glacier NP

Satellite imagery early this morning indicates a region of dry air over the West Coast indicative of a ridge of high pressure. The Northern Rockies will remain under northerly flow aloft ahead of this ridge today. Expect daytime high temperatures to start to creep up above normal, where they will stay for the remainder of the work week. Mostly clear skies this morning will give way to increasing high clouds this afternoon. Moisture riding over the ridge embedded in the northerly flow will arrive tonight, accompanied by a weak disturbance primarily affecting northwest Montana in the form of showers and thunderstorms during the overnight hours. Some high-resolution model soundings indicate enough instability for isolated airmass thunderstorms capable of producing small hail, lightning, and gusty outflow winds of about 30-40 mph.

Northwesterly flow aloft takes over on Thursday as the ridge broadens and moves closer to the Northern Rockies. Showers will linger over the Continental Divide including Glacier Park through Thursday, while the rest of the Northern Rockies sees decreasing clouds. Another weak disturbance arrives on Saturday. About 70% of ensemble model solutions are onboard with widespread cloud cover and light precipitation. Rain or no rain, Saturday will bring a cool-down to near-normal daytime high temperatures.

AVIATION

Winds will take on a more westerly character today, though stay elevated this afternoon. Expect gusts of about 20 knots this afternoon at KMSO, KBTM, and KSMN. High clouds will increase this afternoon as a weak disturbance approaches from the north. KGPI will see chances for showers and thunderstorms tonight by about 07/0300Z. Chances for thunderstorms are about 10-15%. Thunderstorms that do develop will be capable of small hail, lightning, and gusty outflow winds of about 25-35 knots.

MSO WATCHES/WARNINGS/ADVISORIES

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