The West Coast's rainy season has arrived in force, as an atmospheric river carrying moisture from the tropics joins a bomb cyclone off the Pacific Northwest coast. Heavy, wet snow began falling in the mountains on Nov.

A "bomb cyclone" riding a long atmospheric river toward the West Coast is expected to bring more than a foot of rain to parts of Northern California and 30-foot waves to the Oregon coast, but the weather won't be quite as catastrophic in and around Los Angeles, the latest forecast models show.

A developing storm system forecast to swing off the Oregon and Washington coastline on Friday will add to the region's weather woes.