Heavy rain and strong winds began to lash central and southern California Wednesday evening as a powerful ‘bomb cyclone’ washed ashore.

The storm, centered approximately 400 miles west of Eureka, is one of three so-called atmospheric river storms to reach California in the last week.

The bomb cyclone, named for its rapid intensification, is expected to bring two to four inches of measurable rain to Southern California’s valleys Wednesday evening through Thursday with higher amounts likely in the mountains and foothills, according to the National Weather Service.

“Rain rates still look to peak in the 0.50 to 1.00 inch per hour range, with isolated rates of 1.25 inches per hour likely,” NWS said in a bulletin. “This is a lot of water and the threat of flooding is a real concern. Expect a lot of roadway flooding, including a few freeway closures. The Thursday morning commute will be bad.”

The threat of heavy downpours also has officials concerned about possible debris flows around wildfire burn scars. The Los Angeles County Department of Public Works issued evacuation warnings for the following areas:

Winter Storm Warnings were issued for Southern California mountains where heavy snow and potentially destructive winds are forecast. NWS expects areas above 7500 feet in elevation to receive one to two feet of snow accumulation and 4-8″ for elevations between 6500 and 7500 ft.

Lightscape at the Los Angeles Arboretum was postponed because of heavy rain, officials said. Anyone who has to reschedule can email lightscape@arboretum.org or call 626-566-3720.

National Weather Service

The rain also forced the early closure of Knott’s Berry Farm in Buena Park and Six Flags Magic Mountain in Valencia. Knott’s planned to close at 6 p.m., while Six Flags officials announced the closure of the park at 8:30 a.m. Wednesday.

Gov. Gavin Newsom declared a state of emergency throughout California to “keep people safe from the impacts of the incoming storm,” he said in a statement. The declaration allows emergency crews to mobilize quickly and prepare for flash floods, debris flows and other crises.

“This state of emergency will allow the state to respond quickly as the storm develops and support local officials in their ongoing response,” Newsom said.

Although showers should taper off this weekend, more rain is expected to arrive next week.