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A storm system that may include thunder and snow was expected to hit Southern California Sunday night and into the following day, likely slowing Monday’s rush-hour commute, according to the National Weather Service.

Steady rainfall was expected to begin Sunday night, with thunderstorms possible Monday heading into the evening hours, and effects lingering through Tuesday morning, the weather service warned.

Drivers were encouraged to slow down in rainy, wet conditions and allow for extra time as the morning rush-hour commute will likely be slower than normal.

Motorists should also avoid traveling in mountain areas, where snow could drop around 6,000 feet Sunday night and lower to 4,000 feet by Monday afternoon.

As much as 10 inches of snow was predicted to fall above 6,000 feet.

Light snow may also accumulate on the 5 Freeway near the Grapevine on Monday.

If drivers cannot avoid areas that may see snow, they were advised to carry chains and a survival kit.

“Residents of southwest California are encouraged to stay alert and monitor the latest weather conditions and forecasts,” the weather service stated.

Rainfall totals reaching half an inch to 1 inch were anticipated, and debris may flow in recent burn areas.

Large, damaging surf with the possibility of coastal flooding was also expected during the multiday storm system.

Coastal flooding during high tide on Monday and Tuesday was possible, and dangerous rip currents and sneaker waves will make for dangerous swimming conditions, according to the weather service.

Max sets of 18 feet were possible in the central coast Sunday night, with sets up to 25 feet hitting Monday; and in Los Angeles and Ventura counties, max sets of 13 feet were anticipated Sunday night with waves reaching 18 feet on Monday.

Sunday’s expected rainfall would be the second El Niño storm system to fall in the Southland over the weekend.

The first wreaked havoc on the roads Saturday going into Sunday, and multiple crashes occurred, including two that resulted in fatalities.

Although it was unclear if all the incidents were weather related, many occurred on rain-slicked roads.