textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Cooler temperatures and periods of valley rain and mountain snow Saturday evening through Monday

- High pressure bringing stable conditions, temperatures slightly above normal through midweek

- Low confidence for more unsettled weather later next week

Radar returns early this afternoon indicate scattered showers across northwest Montana and Clearwater County in Idaho. Satellite imagery indicates a closed circulation of low pressure over the Pacific Ocean just off the coast of the Olympic Peninsula. This feature is sending moisture into the Northern Rockies resulting in light precipitation and cloud cover. That low will continue to spin over the coast into the weekend before deepening and moving onshore on Saturday night. In the meantime, expect enough moisture to reach the Northern Rockies for partly cloudy to cloudy skies and daytime temperatures to reach just a few degrees above normal.

By the time the Pacific low gets inland on Saturday, it will follow a familiar theme and move south, bringing most of its forcing with it. There will, however, be enough moisture and lift for precipitation focused on north-central Idaho and southwest Montana, as well as the mountains along the Continental Divide, on Saturday night through Monday. Snow levels will be around 5000-6000 feet, which would be low enough for a couple inches of snow on Lost Trail Pass and Gilmore Summit by Monday morning.

High pressure builds for midweek, allowing for stable, warm conditions. The stability could mean fog for the Tuesday morning commute in the valleys of western Montana such as the Bitterroot, Missoula, Mission, and Flathead valleys. Ensemble guidance is hinting at more unsettled weather for later next, but there is still considerable spread in the solutions, so confidence is quite low at this time.

AVIATION

Expect decreasing mid-level cloud cover from south to north into tonight. While localized valley fog is possible in areas that received recent moisture, incoming mid-level cloud cover Friday morning and a weak easterly pressure gradient will largely mitigate fog risk at main TAF sites. Terrain will become obscured by clouds and showers from south to north through the day on Friday as the next disturbance approaches.

MSO WATCHES/WARNINGS/ADVISORIES

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