Bomb Cyclone, Atmospheric River Hammer Pacific Northwest

A bomb cyclone and atmospheric river have combined and settled over the Pacific Northwest this week. The two major weather events have flooded the region with heavy rains, felled trees, and knocked out power to more than half a million homes.  

At least two people died in Washington state as strong winds from the bomb cyclone toppled trees onto buildings and a homeless encampment. Much like a hurricane, a bomb cyclone forms when the pressure at the center of a spinning storm drops 24 millibars or more over a 24-hour period.    

The swirling mass of low-pressure air is forecast to churn off the coast of the Pacific Northwest through Friday. It can cause wind gusts of 50-84 miles per hour and drench the coast with heavy rain.  

The National Weather Service (NWS) issued flood watches and warnings for the region. Some places could get more than a foot of rain by the time the storm passes. Feeding the storm is an atmospheric river. That's a narrow band of densely humid air drawn from the ocean. The NWS warns that the heavy rains may cause landslides and flash floods. At higher elevations, it could cause avalanches. The Sierra Nevada and Cascades Mountains are forecast to get between 16-20 inches of snow. Blizzardlike conditions are likely to last throughout Thursday.  

More than 600,000 homes and businesses were without power Wednesday morning. Most of those were in Washington state. People living along the coast reported howling winds and trees snapping power lines apart. Wendy Harrington told her local news station, KOMO-TV, that a 70-year-old tree fell on her house. She lives in Issaquah, Washington.  

“It felt explosive, like there was a bomb going off,” Harrington said. “Everything was just very loud.”  

Reflect: What would you pack in an emergency kit to prepare for a big storm, and why?