textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Mild temperatures through next Thursday.

- Unsettled weather, with cooler temperatures by Friday into next weekend.

The Northern Rockies will be under the influence of a split flow weather pattern through the middle of next week. Model guidance remains in strong agreement for a closed low to remain nearly stationary off the coast of California by Monday, with the storm track associated with the polar jet remaining across Alaska and northern Canada. This pattern will provide mild temperatures, with day-time highs running around 10 degrees above average across the Northern Rockies. Most areas will remain dry, with isolated showers across north-central Idaho into southwest Montana by Tuesday and Wednesday as moisture spins northward from the low near the California coast.

Forecast uncertainty begins to increase by Thursday into Friday. Ensemble model guidance continues to advertise a wide range of solutions as the longwave trough over Alaska and Canada begins to dive southward towards the Western US by Thursday. The majority of models suggest the this trough will eventually phase with the low of the California coast, bringing increased chances for showers and precipitation by Friday. Details remain uncertain as the track and strength of these low pressure systems remains difficult to pin down. Nonetheless, by Friday into Saturday, around 90% of the models suggest a cool down, with temperatures dropping 10-15 degrees, bringing snow levels down near 4,000-5,500 feet.

AVIATION

Satellite imagery early this morning shows areas of high level clouds moving west to east across the Northern Rockies airspace. Drier air is seen to the west across the Pacific Northwest, with cloud cover expected to decrease through this afternoon. Valley fog will be very isolated in nature this morning, with development focused near larger bodies of water, with KGPI and KMSO having less than a 10% chance of impacts. High pressure is building into the region, with light and variable winds expected for most terminals this afternoon.

MSO WATCHES/WARNINGS/ADVISORIES

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