textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Forecast challenges with valley fog will continue.

- Uncertainty in the pattern change for the next 10 days.

There is now some confidence that while 2 distinct waves drop south out of Canada bringing colder air masses, both systems will be moisture starved. High pressure and valley inversions will be the main theme through at least the 24-26th as of current model runs. The two waves, first on Tuesday and second Friday, will allow for a minor cool down, temperatures across the region may actually drop a couple degrees below normal by Friday, albeit only briefly with slow warming expected throughout the weekend. What is expected is a continuation on the current pattern, valley fog and low stratus improving during the afternoon but returning overnight. This pattern may persist into the following week, i.e. 26 Jan.

The models, which for weeks have been trying to insert a pattern change, have completely backed away from demonstrating change as of the 12z Jan 19 runs.

AVIATION

Little to no changes to the weather conditions for the next 24 hours. Fog and low stratus will continue to impact the valleys of north central Idaho into northwest Montana. KGPI is anticipated to have a stratus deck all day. KMSO could be impacted for a period of time this morning by fog. KSMN should expected hazy conditions, but at this time fog appears to have finally broken out of the area.

MSO WATCHES/WARNINGS/ADVISORIES

MT...ID...Air Stagnation Advisory until 4 PM PST Tuesday for Northern Clearwater Mountains...Orofino/Grangeville Region... Southern Clearwater Mountains.