textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Light valley rain and mountain snow this afternoon and evening potentially causing patchy ice on Tuesday morning

- Mid week ridge: Warmth and stagnant pattern

- Pattern Shift on the Horizon (Feb 8-10): Increased precipitation chances

A weak disturbance is still on track to move through the Northern Rockies this afternoon and evening. Snow levels will be hovering around 4500 feet during the passage of the feature bringing up to 2 inches of new snow to the higher terrain and mountain passes, especially Lolo, Lookout and Marias passes. Areas below 4500 feet will experience some light rain and any roads that remain wet by Tuesday morning could develop patchy ice due to cold sub-surface temperatures.

A strong ridge of high pressure will build over the Northern Rockies for Wednesday through Saturday. This ridge will produce unseasonably warm temperatures in the region, but the extent of warm air making down to the valley floors is still a little uncertain. Confidence is growing that the valleys of Clearwater County and across northwest MT, will develop low stratus/fog, which will hinder the warming. Even these locations temperatures will be running around 10 degrees above seasonal averages, but not be able to reach their full potential. The remainder of the Northern Rockies have a better but still low probability of experiencing daily record warmth by Thursday/Friday time frame, especially down the Bitterroot valley and the Butte/Anaconda region.

The models are still indicating that the ridge should begin to break down during Sunday/Monday of next week. Temperatures should be cooler along with increased chances for precipitation, but the strength of the change is still uncertain.

AVIATION

A weak disturbance will be moving through the region this afternoon and evening causing scattered showers. Freezing level will be hovering around 4500 feet during this passage limiting the snow to the higher terrain which will be obscured at times. KMSO, KHRF, and KGPI have the best potential for vicinity showers throughout the evening. The showers are anticipated to linger across west central Montana overnight into Tuesday morning, potentially impacting KHRF. Any wet surfaces Tuesday morning could develop ice due to cold sub-surface temperatures.

MSO WATCHES/WARNINGS/ADVISORIES

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