California Faces Heavy Rain and Flooding From Coastal Storm

An unseasonably cold and vigorous storm system was cutting through the southwestern Pacific Coast this weekend, bringing rain, flash flooding and snow to parts of California and other states, forecasters said.

The National Weather Service in San Diego had issued a flash flood warning on Saturday morning, cautioning the public about potential flooding in the southwestern part of the state.

The storm was expected to continue moving along the coast and, eventually, inland.

“This storm is going to have an impact all the way across the country, but right now the storm center is off the California coast,” said Bob Smerbeck, a senior meteorologist at AccuWeather. “There’s going to be some flooding issues, mudslides and debris. People should keep their guard up.”

The storm was coming off the coast of California and was expected to shift south and eastward on Saturday or Sunday, creating the risk of flash flooding in Southern California, said Allison Santorelli, a meteorologist with the Weather Prediction Center in College Park, Md.

Los Angeles had received one to two inches of rain as of Saturday morning, and in Santa Barbara and Ventura Counties, the rainfall amounts were two to four inches, Ms. Santorelli said.

The Transverse Ranges and Sierra Nevada could get heavy snowfall, Ms. Santorelli said. Since this was a fairly cold system, significant snowfall was expected above 6,000 feet, with one to three feet of accumulation, and higher amounts possible above 7,500 feet.

Windy conditions were expected to continue, including gusts of 50 to 60 miles per hour above 5,000 feet through Saturday morning, the Los Angeles office of the National Weather Service wrote on Saturday.

Strong winds, combined with the heavy snow, could produce short-term blizzard conditions in the mountain areas, forecasters said. Winter storm warnings were in effect for most of the mountains through Sunday evening.

California is expected to dry out by Monday, Mr. Smerbeck said, but the storm will continue to move into Arizona over the weekend. Western Arizona was expected to experience heavy rain overnight on Saturday and into Sunday.

Arizona was under a wind advisory from noon until 10 p.m. Saturday. The south-central and southwestern portions of Arizona could get a quarter of an inch of rain, according to the National Weather Service in Phoenix.

The storm was also expected to bring significant precipitation to parts of Colorado, Nevada, Utah and Wyoming. As of Saturday, AccuWeather was forecasting a foot of snow in Flagstaff, Ariz.