Marin rainfall could mean icy morning roads

Rain soaked the morning commute in Marin County on Thursday, with the overnight forecast promising an icy Friday morning in some parts of the county.

Parts of the county nearest the bay and along the border with Sonoma County were scheduled for a freeze warning from 11 p.m. Thursday through 9 a.m. Friday, according to the National Weather Service.

“Frost and freeze conditions will kill crops, other sensitive vegetation, and possibly damage unprotected outdoor plumbing,” the agency said.

The agency advised residents to wrap outdoor pipes and either drain them or allow them to drip slowly, and to drain in-ground sprinklers and cover above-ground pipes.

With freezing weather following closely on a rainy Thursday, black ice is a possibility in some parts of the county, said Jeff Lorber, a meteorologist for the service.

Gusty winds during the morning commute prompted the California Highway Patrol to warn motorists to take care crossing the Richmond-San Rafael Bridge. There was also some flooding on Highway 101 in Novato around the time of the morning commute, but it had cleared up by later morning.

Around the Bay Area, the rainstorm put mass transit on roughly 20-minute delays, according to BART.

Farther north, the Lake Tahoe area was under a winter storm warning for Thursday and early Friday, with snowfall predicted between 10 and 20 inches and up to three feet in parts of the Sierra Nevada.

Thursday’s rain will help allay wildfire concerns in the short run, “but if we enter an extended dry period, then those risks are going to be heightened,” Lorber said.

The storm is not atypical for this time of year, Lorber said.

“We’re not looking at excessive rainfall amounts, it is a short period of heavy rain, a pretty potent cold front moving through,” Lorber said. “The front’s moving pretty quickly, so the moisture that’s associated with the front is pretty moderate, so that’s going to limit the flooding potential and overall rainfall amounts.”

The Bay Area News Group contributed to this report.