Here’s what to know about the storm.<\/p>\n
Rare October rainstorm for Southern California<\/p>\n
The Central Coast and Southern California will be closest to the storm’s center Wednesday, raising the odds of bursts of heavy rain.<\/p>\n
The National Weather Service placed the Central and Southern California coast, from Monterey and Big Sur to Santa Barbara, Malibu, Long Beach and Newport Beach, at a slight (level 2 of 4) risk of flash flooding.<\/p>\n
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The National Weather Service warns of a slight (level 2 of 4) risk of flash flooding from excessive rainfall along the coast of San Luis Obispo, Santa Barbara, Ventura and northern Los Angeles counties on Wednesday. A marginal (level 1 of 4) risk extends from coastal Monterey, Orange and San Diego counties to the Nevada border. (Baron\/Lynx)<\/p>\n
“We are seeing rain totals trending upward,” said Bryan Lewis, a meteorologist at the weather service in Los Angeles. “Late Wednesday morning through late Thursday morning will probably be the peak of it.”<\/p>\n
Most coastal and valley areas in Southern California are forecast to get 0.5 to 1.5 inches of rain, with upwards of 3 inches possible in some of the higher terrain. Downtown Los Angeles could pick up 1 to 1.5 inches of rain through Thursday night. That would be more than double what is normal for the entire month, and potentially the city’s wettest October since 2009.<\/p>\n
On the Central Coast, 1 to 1.5 inches is likely near Big Sur and in the Santa Lucia Range, with about an inch in San Luis Obispo.<\/p>\n
The heavy bursts of rain could cause the most problems, especially in wildfire burn areas, including the Timber and Plaskett scars on the Big Sur coast. Forecasters at the weather service’s Bay Area office said there are “definitely concerns for debris flows.” Just a quarter-inch of rain in 15 minutes could be enough to trigger a slurry mix of rock, mud and other debris across Highway 1, according to the U.S. Geological Survey.<\/p>\n
Waterspouts, tornadoes possible from Monterey to Orange County<\/p>\n
The dynamic storm system is likely to produce thunderstorms, particularly around Big Sur and the Central Coast. Some storms could briefly produce a waterspout or tornado. The weather service placed the coast from Monterey to Orange County at a marginal (level 1 of 5) risk of severe weather Wednesday, with a low chance of tornadoes.<\/p>\n
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The National Weather Service forecasts a marginal (level 1 of 5) risk of severe thunderstorms along the Central and Southern California coast on Wednesday. Cloud-to-ground lightning, wind gusts up to 60 mph and a short-lived tornado are the main hazards. (Baron\/Lynx)<\/p>\n
From Wednesday morning into the evening, small but intense thunderstorms could form along the coast, bringing bursts of heavy rain, the potential for strong and damaging wind gusts up to 60 mph and possibly a tornado. Any tornado would likely be weak and short-lived.<\/p>\n
Ocean temperatures along the California coast are up to 10 degrees above normal, which could add heat and moisture to storms as they approach the shore. With a historically strong El Ni\u00f1o in place, downpours, waterspouts and tornadoes are more likely along the coast this winter. During a very strong El Ni\u00f1o in 1983, a tornado damaged more than 100 homes in Los Angeles.<\/p>\n
Up to 10 inches of snow for the Sierra<\/p>\n
A winter weather advisory<\/a> is in effect for the central and southern Sierra Nevada, where a half-foot of snow could fall above 8,000 feet, including the upper elevations of Yosemite, Kings Canyon and Sequoia National Parks. The National Park Service will temporarily close Tioga Pass at 5 p.m. Wednesday in advance of the storm.<\/p>\n Mammoth Mountain could pick up even more snow. A separate advisory<\/a> is in effect for high elevations of Mono County, including Mammoth, for up to 10 inches.<\/p>\n Lake Tahoe is in line for rain, but surrounding peaks like Mt. Rose, Heavenly and Kirkwood mountain resorts could be dusted with an inch or two of snow.<\/p>\n Subscribe<\/p>\n There’s more to San Francisco with the Chronicle. Subscribe today for just 25\u00a2.<\/a><\/p>\n