textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Widespread rain and mountain snow will impact the region throughout Thursday.

- Unsettled weather through the weekend.

- Windy conditions possible Sunday into Monday

The trough of low pressure that is currently over the Pacific Northwest has allowed moisture to continuously stream into the Northern Rockies this morning and early afternoon, especially Clearwater county up into northwest Montana. Snow levels have been hovering around 5000 feet, as the camera for Lookout pass is showing snow but it is not accumulating yet. At this hour the cold front is along the Idaho/Washington/Oregon border and will be pushing through the Northern Rockies during the remainder of the afternoon and overnight. This front will bring an enhancement to the precipitation along with lowering snow levels. The higher elevation valleys and mountain passes south of the line from Lookout Pass to Lincoln Montana will have some snow accumulation by Thursday morning. Some winter weather advisories have been issued for the regions that have the best chance of receiving minor to moderate impacts from the snow. Snow levels will be hovering around 3000 feet by Thursday morning so most locations will have the potential to experience snow, but very warm ground temperatures in the valleys will limit accumulations.

Lingering showers and breezy conditions are expected over the Northern Rockies on Thursday. The strongest winds on Thursday afternoon are expected along the Continental Divide down into Lemhi county, where gusts of 30 to 40 mph will be possible.

This active weather pattern will persist Friday into Saturday. Temperatures will be running near to slight above average for this time of year. Snow levels are expected to slowly climb back up to around 5000 feet by Saturday afternoon as the region experiences off and on light showers.

The longer range models are indicating at a disturbance will drop southward out of Canada Sunday into Montana. This feature will bring widespread precipitation and cooler air, but the biggest concern will be the potential for windy conditions. The mountains of northwest Montana have a 50 to 70% chance of gusts greater than 50 mph on Sunday afternoon, then on Monday that probability extends southward for all the higher elevations of western Montana and Lemhi county.

AVIATION

A plume of steady precipitation will continue to move across the Northern Rockies this afternoon and evening. A cold front will push through the region this evening causing snow levels to drop to around 5000 feet. KBTM and KSMN have the best potential of having impacts to visibility due to the snow this evening and overnight. KGPI and KMSO could experience the development of mist/fog by Thursday morning.

MSO WATCHES/WARNINGS/ADVISORIES

MT...Winter Weather Advisory from 6 PM this evening to 9 AM MST Thursday for Butte/Blackfoot Region.

Winter Weather Advisory until 9 AM MST Thursday for Bitterroot/Sapphire Mountains.

ID...Winter Weather Advisory from 6 PM MST /5 PM PST/ this evening to 9 AM MST /8 AM PST/ Thursday for Eastern Lemhi County... Southern Clearwater Mountains...Western Lemhi County.