Radar map shows approaching showers
National Weather Service radar shows a line of heavy showers along the coast at 5:35 a.m.

A  Pacific storm moving through Southern California brought heavy rain and thunderstorms to coastal areas of San Diego County just before daybreak on Monday.

“Moderate to locally heavy rain will become more widespread throughout the morning making for a wet commute,” the National Weather Service warned. ” If you’re on the road, use caution and if you come across a flooded roadway, remember turn around don’t drown.”

Caltrans reported two morning truck accidents on Interstate 805 in Chula Vista and closed two lanes on northbound Interstate 15 at Route 78 after a collision involving a big rig in Escondido.

Monday’s forecast calls for rainfall in the .5- to 1-inch range across the region. Localized urban flooding is possible but the flash flood risk low, the weather service said.

Snow levels will be at 5,500 to 6,000 feet on Monday, falling to 5,000 feet early Tuesday.

The storm is the first of two that will hit the region this week. A colder cell arriving Christmas night and lasting through Thursday will see temperatures plummeting and rain levels increasing, weather officials said.

“Most substantial rain and mountain snow will occur through Monday, with another round Christmas night through Thursday,” a weather service report said.

Rainfall will end Friday with dry weather likely next weekend, according to forecasters. Another Pacific storm could arrive by New Year’s Eve.

Updated at 9:10 a.m., Monday, Dec. 23, 2019

— From Staff and Wire Reports

Chris Jennewein is founder and senior editor of Times of San Diego.