textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Thunderstorms return to Lemhi County, Idaho, and southwest Montana with the weather pattern during weekend, bringing lightning and brief, erratic wind gusts

- Warming trend Tuesday through Thursday

- Cooler and showery conditions expected next weekend

Two weak disturbances will be interacting over the Northern Rockies today into Sunday. The first disturbance is located over the Great Basin region pushing in some monsoonal moisture into Lemhi county and southwest Montana. The other disturbance will be dropping out of British Columbia today into Sunday, limited the northward progression of the monsoonal moisture. This afternoon the best chance of shower and thunderstorm activity will be mainly across Lemhi county into southwest Montana, but a few storms could develop as far north as Missoula up to Seeley Lake/Ovando region. These storms will be capable of producing gusty erratic winds, lightning and brief heavy rain. The shower activity is expected to diminish after sunset this evening.

The British Columbia disturbance will continue to track along the Canadian border on Sunday causing wrap around shower activity across northwest Montana. This disturbance will also push in cooler air causing temperatures to be near seasonal averages for Sunday into Monday.

A ridge of high pressure will be building over the region Tuesday through Thursday. Temperatures will be steadily climbing each day with Wednesday and Thursday potentially being the warmest days so far this year. Most valley locations should be in the upper 80s to low 90s by Wednesday afternoon with the lower valleys of north central Idaho breaking the century mark.

The far majority (over 75%) of the long term models are showing a trough of low pressure moving into the Pacific Northwest by next weekend causing cooler conditions along with widespread shower activity.

AVIATION

Moisture will continue to push into Lemhi county and southwest Montana today causing scattered showers. Instability this afternoon will lead to the potential development of thunderstorms that could impact KSMN and KBTM. These storms will be capable of producing gusty erratic winds, lightning and brief heavy rain. KMSO and KHRF have a lower probability of being impacted by these storms. The shower activity is expected to diminish after sunset this evening.