Season's strongest storm: Autumn storm hits NW

The fiercest Pacific storm of the season is roaring ashore, bringing heavy rain, damaging winds and even blizzard conditions.

The WeatherRadar shows heavy rain moving onto the West Coast, soaking northwestern California, western Oregon and western Washington. The darker blue shows the heaviest rain continue through tonight.

The higher elevations of the Cascades and the northern Sierras will receive 10 to 20 inches of snow, causing travel problems over the highest peaks. Travelers will need chains or winter tires to cross the highest mountain passes.

High winds will accompany the heavy rain and snow. The WindRadar above shows winds in excess of 35 mph and gusts reaching 50-plus mph along the Northwest coast, with Seattle seeing gusts in excess of 40 mph. This will cause localized power outages and cause snow to drift across mountain passes. Blizzard warnings have been posted for the Cascades and travelers should carry their winter survival kits and heed these warnings.

This is the beginning of a busy stretch of rain and snow across the West Coast. Waves of heavy rain will continue through Friday across northern California as an atmospheric river and a bomb cyclone sets up offshore.

An atmospheric river event occurs when the stream of moisture from the sub-tropical Pacific near Hawaii is picked up by the jet stream and brought into the West Coast. This feeds prolonged heavy rain.

Northern California and western Oregon will receive more than 8 inches of rainfall by Friday, with a foot possible in coastal mountains. As wintry weather becomes more common, make sure you have your alerts turned on to get the latest details on when a winter storm threatens.