Marine Weather and Tide Forecast for Finley Point, MT

FXUS65 KMSO 071901 AFDMSO

Area Forecast Discussion National Weather Service Missoula MT 1201 PM MST Sat Dec 7 2024

DISCUSSION

KEY MESSAGES:

- Freezing rain remains a threat in northwest Montana through this evening.

- Snow bands are possible behind the front tonight, though only weak bands are expected.

- Snow showers will form across the region Sunday afternoon and may put a quick few inches of snow down in isolated locations.

Cold pools are well established in northwest Montana this afternoon, with temperatures in the mid and upper 20s in the valleys and temperatures in the mid and upper 30s in the mountains. Additionally, the Spokane weather radar (KOTX) is showing a melting layer reaching up to around 7,000 ft elevation.
Radar shows some returns stretching from Lincoln county into Flathead county of northwest Montana. Additionally, we have a spotter report from Libby of very light rain that began just after 10 AM this morning. Given radar returns, precip reports, and temperature profiles, freezing rain remains a concern for that area, and a winter storm warning remains in effect there until 5 PM today.

This evening a cold front will pass through the region and wipe out the layer of warm air aloft, causing a transition to all snow.
There isn't a lot of moisture to work with behind the cold front, so precipitation amounts are pretty light, though there is concern about showers organizing into bands. There will be a brief period of instability very early Sunday morning, but the stronger instability won't get started until Sunday afternoon. A lack of directional wind shear, which just means the winds are aligned from the same direct at all elevations, up over 10,000 ft support showers forming into bands. The only missing ingredient for a classical snow band scenario is a stable layer of air around 10,000 ft elevation. As such, we expect the showers to form bands, but not persistent, stationary bands. As a result, peak snow accumulation Sunday under snow bands is expected to be 1-2 inches.

By Wednesday, a sharp ridge builds over the region and will last for about a day and a half. Since the previous cold front will have scoured out valley cold pools, it will take time for the next ridge to build up the low level moisture needed for fog, and this ridge won't be around that long. So we expect fog impacts the middle of the weak to be more isolated and right along the river corridors. Any fog affecting area airports will not persist all day, but will generally break up by early afternoon, if it gets that bad at all.

Ensembles agree very well on another short wave coming through Thursday causing another round of light mountain snow. And, in general, the pattern remains active with low to moderate impacts from mountain snow through the rest of the extended.
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