National Weather Service United States Department of Commerce

Prolonged Atmospheric River Will Impact the Northwest Early this Week

A weather system in the Pacific Northwest will produce rain throughout the day, before a potent atmospheric river produces a prolonged round of heavy rainfall, widespread urban and river flooding, and high elevation snow to the region Monday through Wednesday. Showers and thunderstorms may produce isolated damaging winds, a brief tornado, and locally heavy rainfall across parts of Florida today. Read More >

🚨 ICYMI: Significant Atmospheric River this Week 🚨 Multiple rounds of Pacific moisture from Atmospheric Rivers will target the Northern Rockies through Thursday (Dec 11). This long-duration event could bring moisture totals rivaling historic amounts for this time of year. ⚠️ Key Impacts & Concerns: 💧Risk for roadway ponding, urban flooding, including basements. 📈 Sharp rises on creeks and streams. 🪨 Risk for rock and mudslides in steep terrain. 📍 Flood Watch Area: The greatest flood risk is across Idaho, Clearwater Counties in Idaho, and Lincoln, Flathead, Lake, Sanders, Mineral Counties in Montana, where a Flood Watch is in effect. ❄️Heavy, wet mountain snow above 7,000-8,000 ft bringing changeable avalanche conditions! Check www.avalanche.org for the latest forecasts.
Winter Weather Alert for the Wednesday Morning Commute ❄️🚗 Heads up, Northwest Montana! A quick burst of moderate to heavy snow is expected to impact travel conditions from midnight through 11 AM Wednesday. 📍 Where: Northwest Montana, specifically impacting Marias Pass, Seeley Lake, Yaak area, and the Flathead & Mission Valleys. ⚠️ Impacts: Snowfall Rates: Bursts of 0.5" to 1" per hour are possible. Travel: Expect slick conditions and reduced visibility during the morning commute. Snow Levels: Generally 3000-4000 ft, with brief wet snow possible in the valley floors. Please allow extra time for your commute on Highway 2, Highway 93, and Highway 200 in these areas.
Strong winds are again possible on Wednesday. There is a concern for localized tree damage and power outages. Also, trees may fall into roadways given the saturated grounds in some valleys.

 

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