textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Many valleys reaching the mid-50s to low 60s this afternoon.

- Rain and mountain snow will reach the entire region starting Wednesday morning, with an 80% probability of measurable precipitation.

- A cold front will move through Wednesday night, bringing gusty winds from the west (30-40 mph) and dropping snow levels to near valley floors by Thursday morning.

Today, a ridge of high pressure is centered directly over the Northern Rockies. This will result in afternoon breezes and mostly sunny skies. High temperatures will rise into the mid-50s and low 60s for most Montana valleys and north-central Idaho.

A fast-moving Pacific storm system will move across the region on Wednesday. Initially, mountain passes such as Lookout Pass are expected to start with rain before transitioning to snow during the day Wednesday. A cold front will bring cooler air into the region late Wednesday night into Thursday morning. There is some uncertainty regarding the exact timing of this front. Computer models show the storm system losing its shape as it moves south, which could delay the arrival of colder air. If the front is slower, Thursday morning may remain rain or a rain/snow mix in the valleys; if it is faster, we will see a quicker transition to all snow.

Westerly winds will become gusty behind the front. Expect gusts of 30 to 40 mph, particularly along the Continental Divide and through the Butte and Blackfoot regions.

The region remains under an unsettled weather pattern from Friday through Monday. Expect hit-or-miss snow showers to continue, primarily over the mountains. Breezy conditions will persist, likely peaking again on Sunday.

Long Range: We are tracking a 30% probability of an Arctic weather system arriving as early as March 9th, or as late as the 12th. While the rest of the cluster ensemble members are not showing an Arctic system, they do show a colder and wetter pattern as opposed to where we have been. This remains the primary focus for potential high-impact winter weather in the extended forecast.

AVIATION

A quite weather pattern will continue across the region through this evening as high pressure dominates. Clouds will continue to thicken and lower from the west tonight ahead of an approaching Pacific storm. Expect cloud ceilings to lower and visibility to decrease at KGPI, KMSO, and KHRF after 04/1200Z. Wednesday as rain and mountain snow move into the Northern Rockies. KMSO, KGPI and KHRF will see periods of lower visibility under light rain showers beginning around 4/1700Z through 5/0000Z.

MSO WATCHES/WARNINGS/ADVISORIES

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