textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- A ridge building over the region today will cause temperatures to warm.

- A surge of monsoonal moisture Friday night into Saturday may bring thunderstorms capable of heavy rain and gusty winds to southwest Montana and Lemhi County.

Forecasts are highly confident that a strong ridge of high pressure will build across the Northern Rockies tomorrow. This weather pattern will bring quick warming, pushing tomorrow afternoon temperatures into the mid-to-upper 80s across western Montana and into the mid-90s in the lower valleys of central Idaho. Computer models show a slight chance for scattered showers to develop across western Montana this afternoon, with a few thunderstorms possible along the Continental Divide in northwest Montana.

By late tomorrow night, an unusually strong surge of monsoonal moisture will move north from the Great Basin, combining with a weak upper-level shortwave. This combined moisture and energy will bring widespread showers and thunderstorms, primarily impacting Lemhi County and southwest Montana through Saturday. The main impacts from these storms will be heavy rain and sudden, strong wind gusts. Uncertainty remains regarding how far north these storms will travel, though some models show the rain and storms moving as far north as Missoula. Once this system clears out, a high-pressure ridge will quickly rebuild over the region, starting another period of hot, dry weather.

AVIATION

A ridge centered over the U.S. West Coast will extend its influence further east into western Montana today. Since the region is on the eastern edge of the ridge, expect some gusty northwest winds in the afternoon with gusts up to 20KT. Otherwise, VFR conditions prevail.

MSO WATCHES/WARNINGS/ADVISORIES

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