Grapevine-area drivers on alert for dangerous road conditions as storm system moves in

GRAPEVINE, Calif. (KABC) -- The National Weather Service warned of a cold "atmospheric bowling ball'' that will produce a "strike'' of snow as it crosses through the Grapevine overnight into Monday, and drivers are on high alert.

Traffic was moving slowly through Castaic Sunday afternoon, but the California Highway Patrol continues to warn drivers, saying officers could shut down roadways if heavy snow begins to fall.

Steady rain fell throughout Southern California with minor flooding, mud and debris flows closing some roads.

The Los Angeles County Department of Public Works reported Sunday morning that Lake Hughes Road, between Pine Canyon and Dry Gulch roads in Lake Hughes, was closed due to mud and debris on the roadway. The department was asking the public to avoid the area and use alternate routes.

The Pomona Police Department reported flooding at the underpass at First Street, with several streets in the area either closed or affected by flooding, including South Reservoir Street, South Towne Avenue, East End Street, Garey Avenue and White Avenue.

Heavy rain was falling in the northern San Fernando Valley, where CHP was at the scene of a big-rig crash on northbound I-5 at Sheldon Street in the Sun Valley area. The vehicles involved in the crash were cleared around noon, but both sides of the freeway were flooded as of 12:30 p.m. The three right lanes were blocked on the northbound side with the HOV and left lane open, and the three right lanes were blocked on the southbound side with the left lane open.

Caltrans had its pumps on the scene trying to clear the water.

In Orange, firefighters and paramedics pulled a man from the river during a swift water rescue in the area of the Santa Ana River and Garden Grove Boulevard. He was taken to a hospital for follow-up care.

"Received significant rainfall over our mountains last night and we are starting to see a response in our local main stem rivers. Not enough to reach monitor or flood stage, but finally seeing some flow,'' the National Weather Service's Los Angeles office tweeted at 8:33 a.m.

Shortly after 9 a.m., the NWS said Doppler radar indicated heavy rain due to thunderstorms in south Orange County, and minor flooding expected to begin in Irvine, Mission Viejo, Rancho Santa Margarita, San Clemente, Laguna Beach, Dana Point and Laguna Niguel.

Forecasters said heavy downpours and small hail were possible in some areas through Sunday evening.

The Angeles National Forest said roads in the forest might be very slick and/or closed due to rain or snow. Tire or snow chain requirements could be in effect.

The storm is expected to pass through the area by Sunday night. Some lingering showers will be possible Monday morning, primarily in mountain areas, forecasters said.

City News Service, Inc. contributed to this report.