A powerful, highly erratic storm tore through the Pacific Northwest on Tuesday, taking out power for over 100,000 in the Seattle area — with more to come.

Though that type of weather system doesn’t often develop near Washington, the last one that impacted the Pacific Northwest was earlier this year in January. Bomb cyclones are weather systems that form when the storm’s central pressure drops more than 24 millibars in 24 hours.

Severe storm will bring strong winds to Washington state and the rest of the West Coast. Here’s when experts say conditions will be worst.