Bomb Cyclone Brings Heavy Rain, Wind, & Snow to California

An intense mid-latitude cyclone has been aiming for the West Coast of the United States this week, ushering a strong atmospheric river into Oregon and California. This low-pressure system underwent bombogenesis, or it "bombed out," a term reserved for low-pressure systems that intensify rapidly, typically with a pressure drop of at least 24mb in 24 hours. This storm system more than doubled that pressure drop, going from over 1000 mb to about 945 mb in 24 hours! This intense storm system is expected to continue to bring major impacts to areas of the Northwest and northern California with heavy rain, strong winds, and big swells.

This strong low-pressure system is tapping into moisture from the tropics, pulling intense rain and snow into northern California. This has led to the likelihood of flash flooding in northern Californiacontinuing across the northern Sierra on Friday. Warm temperatures will keep precipitation falling largely as rain below 6,000-7,000 ft before the cold front arrives on Friday afternoon to drop snow levels back to around 4,500 feet into Saturday morning.

A moderate risk for excessive rain continues Friday before the threat drops to marginal (level 1) for the Sierra foothills on Saturday.

Rainfall is expected to be heavy through Saturday, with rainfall totals possibly surpassing a 8-10" in Southern Oregon and Northern California. Flooding, including river flooding and flash flooding, is likely in these areas. If you live in a low-lying area that can flood, be ready to leave if flash flood warnings are issued.Areas along the coast could also see strong enough winds to down trees and power lines.
Check back in with WeatherNation on air and online for updates on this impactful storm system.