Area Forecast Discussion

DISCUSSION

KEY MESSAGES:

- A cold front moving north to south across the region tomorrow will cause some thunderstorms and gusty winds.

- A ridge building over the Pacific NW this weekend and early next week will cause a warming trend with temperatures in the upper 70s mid 80s in western Montana and mid 90s in central Idaho next week.

A trough and surface cold front dropping out of Canada tomorrow will cause some thunderstorms and gusty winds. Current forecasts are for moderate thunderstorms with gusty winds around 40 mph, small hail, and heavy rain. Overall, we expect scattered thunderstorms of average intensity for western Montana. Thunderstorm chances are confined along I-90 and northward, so Idaho will be missing out on these storms.

The ridge over the northeast Pacific Ocean will move inland and set up over western Washington and Oregon this weekend and into early next week. That will leave the northern Rockies under northwest flow. This is typically a showery pattern, but without much moisture to work with they are generally light showers and mostly confined to the mountains. With the ridge building in just west of our region, it will allow temperatures to finally warm up with some 90s expected in the low elevations of central Idaho like Orofino and Riggins by Tuesday. Western Montana will warm into the mid 80s.

With the ridge axis to our west, this is a good pattern for occasional short waves to drop out of the northwest and cause showers and a cool down. Current forecasts don't show this happening yet, but it's the kind of subtle pattern that the models frequently miss at long lead times. In any case, it would be a low impact scenario if it does happen. Also, there is very poor agreement among the ensembles as to when the ridge breaks down, though many members start to show some sort of cool down by late next week.

AVIATION

A ridge building over the U.S. West Coast will keep conditions mild today. A shortwave moving down the eastern edge of that trough will drag a cold front across the region tomorrow. Expect thunderstorms during the afternoon tomorrow with gusts up to 40 mph. Once the front moves through in the evening, it will shut off convection pretty quickly as more stable conditions develop.

MSO WATCHES / WARNINGS / ADVISORIES

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