Tens of thousands of homes in Washington state lost power Tuesday and downed wires or trees locked some highways as Northern California and the Pacific Northwest started feeling the effects of a powerful atmospheric river event,

A low-pressure system headed for Northern California and Oregon is likely to bring extreme rain and strong winds.

Bomb cyclone is a term used by weather enthusiasts to describe a process that meteorologists usually call bombogenesis. It's the rapid intensification of a cyclone in a short period of time, and it can happen during powerful storms such as the one no rthern California and the Pacific Northwest are preparing for this week.