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,

An atmospheric river is a narrow band of wind that carries immense plumes of moisture, spanning hundreds or even thousands of miles, resembling a vast river in the sky. NBC News' Chase Cain reports on the challenges this phenomenon poses for the West Coast.

The Northwest is bracing for a strong storm system to move in this week, fueled by an atmospheric river​ and bomb cyclone. What do those terms mean?