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Many cities recorded about 1 inch of rain over the past 48 hours
MONTEREY » Although largely aimed at the Central Coast and Southern California, an “atmospheric river” also delivered a drenching to the Bay Area on Thursday, boosting local rainfall totals but wreaking havoc on roadways.
As of 5:15 p.m. Thursday, 24-hour rainfall totals around the Bay Area included 1.53 inches in Kentfield, 1.11 inches in Redwood City, .58 inches in Richmond, .54 inches in Concord, .51 inches in San Francisco, .41 inches in Oakland and .34 inches in San Jose.
The lack of significant rainfall in San Jose was due in part to the “rain shadow effect,” a phenomenon in which a mountain range or other topographic barrier causes prevailing winds to lose moisture on the windward side. The Santa Cruz Mountains absorbed most of the rainfall, leaving San Jose with just a few drops in comparison.
“As the air comes over the hills, it ends up drying out or evaporating the rain,” said Matt Mehle, a meteorologist with the National Weather Service in Monterey.
Scotts Creek and Ben Lomond in the Santa Cruz Mountains have recorded more than 5 inches of rain since the storm system’s arrival in the Bay Area on Tuesday morning.
The wet weather kept the California Highway Patrol busy Thursday. Flood- ing shut down Highway 121 at Highway 12 and dozens of collisions were reported to the agency.
Periods of moderate to heavy rainfall were expected throughout the Bay Area on Thursday night, along with breezy to locally gusty southerly winds, according to the weather service.
The atmospheric river -- a plume of subtropical moisture -- delivered a more significant soaking to the Central Coast and Southern California. Several single- day rainfall records were broken Thursday, including 1.91 inches in Paso Robles, .76 inches in Sandberg and .41 inches in Palmdale, according to the National Weather Service in Los Angeles.
In Big Sur, the Big Sur River came within half a foot of flood stage, cresting at 9.57 feet at 2:30 p.m., the weather service reported.
The storm system is also bringing rain and snow to the Sierra Nevada. The National Weather Service in Sacramento has issued a winter storm warning for the greater Lake Tahoe area through 5 a.m. Friday, saying 8 to 16 inches of new snow is possible.