First big winter storm reaches California. Here’s what it means for the water year

California finally got its first real taste of winter weather Monday as a substantial rainstorm swept through the state, causing numerous traffic accidents and bringing warnings of flooding and mudslides in areas burned by wildfires.

The National Weather Service said much of the Sacramento Valley could receive up to 2 inches of rain by the time the storm winds down late Tuesday or early Wednesday. Although the storm started out fairly warm, bringing mostly rain, parts of the Sierra Nevada could expect as much as 30 inches of snow.

“It’s a pretty significant (weather) system here, more moisture than the previous systems that have come through here,” said Mike Kochasic of the National Weather Service in Sacramento.

Combined with light rain that fell late last week, the storm represented the first significant precipitation in the Sacramento area since Dec. 20, ending a lengthy dry spell that had climatologists fretting about a dry winter.

Rainfall in Sacramento has totaled just 3.57 inches since the “water year” began Oct. 1, or 45 percent of normal, and the new rainfall won’t be enough to bring the region up to par.

The new storm “will make a decent dent,” Kochasic said.

He said snow won’t fall in the mountains below around 7,500 feet, although temperatures will turn cooler and the snow line will drop tomorrow to around 6,000 feet. A winter weather advisory for motorists will take effect 4 a.m. Tuesday, he said.

Sierra ski resorts, which have slogged through the winter so far, said the fresh snow will likely bring more customers. Business at Sierra at Tahoe, near Echo Summit off Highway 50, hasn’t been as strong as last winter but could perk up.

“When we have more snow, it brings more people,” said resort spokeswoman Thea Hardy. “We’re optimistic about the storms that are coming in.” Sierra at Tahoe has 17 runs open, out of 46.

The rains were proving problematic for others. The National Weather Service issued a flash flood warning for Sonoma County, site of the deadly wine country fires in October. “Heavy rain on the North Bay burnscars could result in debris flows, mudslides and flash flooding,” the weather service said.

In Southern California, evacuations were ordered in Santa Barbara County neighborhoods directly below the areas burned during the Thomas Fire in December, according to the Los Angeles Times. The region, which has been almost completely dry this winter, was expected to get as much as 4 inches of rain by early Tuesday.

Areas scorched by wildfires create almost instant runoff when it rains, as there’s little or no vegetation to soak up the water.

In the Sacramento area, the rain caused hiccups for many during the morning commute. The California Highway Patrol’s Sacramento Communications Center reported 16 car crashes between 7 and 9 a.m., at least six of which caused injuries. No fatalities were reported.

Kochasic said the Sacramento area will start drying out Wednesday, with no more precipitation expected until early next week. “For the foreseeable future, it looks like we might get something creeping in Monday,” he said.

Dale Kasler: 916-321-1066, @dakasler