A powerful storm is expected to bring several days of heavy rain, strong winds and mountain snow to parts of the Western United States this week. The storm is the result of an atmospheric river. … The atmospheric river season typically runs from October through March, and is responsible for up to half of California’s annual precipitation. While these systems are vital to replenishing water supplies, they can also cause flooding when they combine with other weather systems, bringing heavy rainfall. … Heavy mountain snow was expected across parts of mountain ranges like the Cascades, the Northern Sierra Nevada and the Northern Rockies.

Other atmospheric river and weather news:

• KQED (San Francisco): Bay Area’s getting wet again, as an atmospheric river opens the door to winter
• San Francisco Chronicle: Bay Area could get more rain this weekend than expected if atmospheric river comes closer
• KCRA (Sacramento, Calif.): Northern California rain and snow forecast: Expected totals for this weekend
• USA Today: 2 feet of snow? ‘Atmospheric river’ takes aim at West Coast.
• KABC (Los Angeles): NOAA forecast predicts drier than normal winter in SoCal