Thanks to plenty of moisture across the Northwest, mountainous snow and valley rain will continue into the start of the work week.
A moisture rich environment courtesy of an atmospheric river will affect northern California, portions of the Pacific Northwest and Upper Rockies through Tuesday night. The Cascades, Sierra Nevada, Olympic Mountains, and portions of the Pacific Coast Range in northern Oregon and northern California will see snow amounts of 2 to 4 feet after combining this weekend’s snow totals. Lower elevations in Washington, Oregon and northern California will see 3 to 6 inches of snow while eastern and central Oregon will see 5 to 10 inches as this first round of activity concludes Tuesday night.
Similar mountainous snow is also expected for the Rockies in Idaho and western Wyoming through Tuesday night. Here, 2 to 4 feet of snow is also expected. Six to 12 inches will occur in western Montana, but isolated amounts of 1 to 3 feet may occur amongst the higher elevations. Lower elevations in northern Idaho as well as central and eastern Montana will see 3 to 6 inches of snow.
Winter Storm Warnings, Winter Weather Advisories, and Winter Storm Watches remain in effect from central and northern California into the Washington Cascades, as well as for western Wyoming, Salmon River Mountains and Bitterroot Range in Idaho, and across all of Montana. This includes Mount Shasta, Calif., Cave Junction, Crater Lake and Mount Hood, Ore., Toledo and Mount St. Helens, Wash., Idaho City, Palisades and Lowell, Idaho, Cody and Sheridan, Wyo. And Miles City, Glasgow, Eureka, Billings, Great Falls and Missoula, Mont.
Heavy snow is not the only wet weather this atmospheric river will deliver. Heavy rain is expected for portions of central and northern California where Flood Watches are in effect, particularly in the Sacramento Valley. This includes Stockton, San Francisco, Sacramento, Modesto, and Paradise, Calif. These locations will be drenched with at least 1 to 3 inches of rain through Tuesday while the Sierra Foothills will see as high as 10 inches of rain!
Dangerous travel conditions may occur thanks to this heavy rain. Urban and flash flooding, especially in low-lying, flood-prone areas, will be possible. River, stream and creek flooding may also occur due to excess runoff. Mud and rockslides will be possible in the foothills and mountains as well.
The atmospheric river is not done yet as even more valley rain and mountainous snow will target the same locations to close out the work week.