Marine Weather and Tide Forecast for Turtle Lake, MT

FXUS65 KMSO 122116 AFDMSO

Area Forecast Discussion National Weather Service Missoula MT 316 PM MDT Thu Mar 12 2026

DISCUSSION

KEY MESSAGES:

- Snow levels lowering into the valleys tonight causing wintry travel, especially along and north of Interstate 90.

- Valleys in north central Idaho (Grangeville to Elk City) will remain in moderate to heavy rain, elevating the risk for rockfalls, snow sloughing, and minor river rises.

- An Arctic boundary moving into western Montana(70% chance)
Saturday evening will tap into instability to trigger intense bands of snow between Kalispell to Missoula/along I-90/Hwy200.
With wet roads from daytime melting, a rapid freeze-up and slick roads are possible.

The cold front responsible for this morning's damaging winds has exited the region, though strong flow aloft continues to produce mountain ridge gusts of 40 to 60 mph. While lingering showers may briefly transport higher momentum to valley floors, the threat of widespread damaging winds has diminished, except for Lemhi County where strong winds will persist through early evening.

Attention shifts to an anomalous atmospheric river stalled from the WA/OR border into west-central Montana. The primary forecast challenge remains snow levels; heavy precipitation rates are expected to drive snow levels below model guidance via top-down cooling. Valleys in northwest Montana are likely to see several inches of accumulation by morning. Along the Interstate 90 corridor, including Missoula, the forecast is more nuanced. A slight lowering of snow levels tonight could result in 1 to 4 inches of heavy, wet snow for Sanders, Mineral, Missoula, Granite, and Powell counties. Given the potential for slushy accumulations, winter weather advisories may be required.
Conversely, further south near Grangeville and Elk City, precipitation will remain predominantly rain, maintaining an elevated risk for rockfalls and snow sloughing.

A shortwave trough will transit the region on Saturday morning, eroding the subtropical moisture plume and introducing gusty post- frontal winds up to 35 mph. As the atmosphere becomes highly unstable by Saturday afternoon, snow and graupel showers will develop. Of significant concern is an Arctic boundary projected to plunge south from Alberta Saturday evening (70% probability).
This front will likely trigger intense snow bands between Kalispell and Missoula and eastward toward the Continental Divide.
Rapidly falling temperatures on wet roads may create a high risk for flash freeze conditions and dangerous travel before activity wanes by midnight.

Sunday provides a brief, cold reprieve before overrunning moisture from a British Columbia-bound atmospheric river reaches the region Sunday night. This warm-frontal passage will likely reintroduce wintry travel impacts to the mountains and northern valleys. Looking ahead to next week, ensemble guidance strongly favors the building of a high-amplitude ridge. Despite occasional "dirty" ridge cloud cover, a significant warming trend is expected, with temperatures rebounding into the 50s and 60s.
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