Following the bomb cyclone, the region faces days of rain, flooding and snow at higher elevations, the National Weather Service said Wednesday. That's part of an atmospheric river that could bring over a foot of rain to some areas.

More than 500,000 energy customers across the West Coast were without power early Wednesday and one person was killed by a falling tree as severe weather caused by back-to-back powerful storm systems began battering the Pacific Northwest.

A powerful atmospheric river is slamming into Northern California and is expected to persist for days. Its effects, coupled with a bomb cyclone offshore, are being felt across the Pacific Northwest.