A wintry storm could dump significant rain and snow on portions of California, bringing damaging winds and flash floods to parts of Southern California, especially in and around burn scars, the National Weather Service has warned.
Here’s what forecasters are predicting, although they caution the situation is evolving and subject to change.
Monday into Tuesday
The core of the storm, which is expected to bring the most damaging impacts, is predicted to move through San Francisco and Santa Barbara counties starting Monday evening and will likely reach Ventura and Los Angeles counties after midnight, said Ryan Kittell, meteorologist with the National Weather Service in Oxnard. Those areas may see light showers both before and after the core moves through, he said.
Peak rates of 0.25 to 0.5 inches of rain per hour are possible, with total accumulations of 0.75 to 1.5 inches for coastal and valley areas and 1.5 to 3 inches in the mountains, according to the weather service. Severe thunderstorms could also bring more intense downpours in some places, as well as heavy winds that could take down trees and power lines, forecasters cautioned.
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“The setup for the storm is similar to storms in the past that have produced thunderstorms that created pretty strong winds and even a weak tornado or two,” Kittell said. “And while it’s really hard to say for certain that this will happen over the course of the next 24 hours, it’s an appreciable risk for isolated storms to produce impacts like that.”
Starting at 8 p.m. Monday, a flood watch is in effect for areas in and near recent burn scars in San Luis Obispo, Santa Barbara, Ventura and Los Angeles counties. The scars are from the Gifford, Madre, Lake, Apache, Mountain, Post, King, Canyon, Hughes, Hurst, Kenneth, Franklin, Palisades, Sunset, Lidia, Hawk, Eaton and Bridge fires that burned over the last two years. The flood watch is in effect through 3 p.m. Tuesday. Debris flows are also possible.
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Flooding may also take place in urban areas, areas with poor drainage and low-water crossings, forecasters said.
The National Weather Service also issued a flood watch for burn scars in the San Bernardino County Mountains, Santa Ana Mountains and foothills and inland areas of Orange County from late Monday until Tuesday afternoon. Burn scars include those from the Bridge, Line, Apple, El Dorado and Airport fires that burned over the last five years.
Forecasters are predicting rainfall rates of 0.3 to 0.7 inches per hour in those areas.
For much of the high desert, including Apple Valley and Lucerne Valley, the San Gorgonio Pass near Banning, the Antelope Valley and the Morongo Basin, a wind advisory is in effect until 11 p.m. Tuesday, with gusts of up to 45 mph expected.
Farther north along the Central Coast and in the Central Sierra, the heaviest portion of the storm is expected to hit from 11 p.m. Monday through 5 a.m. Tuesday, said Emily Wilson, meteorologist with the National Weather Service in Hanford.
Snow levels are expected to drop to 6,000 feet, with accumulations of 4 to 8 inches from 7,000 to 8,000 feet and 1 to 2 feet above 9,000 feet. At lower elevations, hourly rain rates could range from 0.2 to 0.3 inches per hour, she said.
A flood watch is in effect from 5 p.m. Monday through Tuesday afternoon for rural and mountainous areas like Camp Nelson, Coarsegold, Oakhurst, Kernville, Fish Camp, Lake Isabella, North Fork, Auberry, Bass Lake and Yosemite Valley. A winter storm warning is in effect until 5 p.m. Wednesday for some communities near Yosemite National Park and Sequoia and Kings Canyon national parks, as well as on the Eastern Sierra slopes.
Tuesday into Wednesday
Showers may linger, but by Tuesday afternoon the most damaging impacts from the storms are expected to be over.
Cooler temperatures are expected throughout the state to last into Thursday, followed by a warming trend.
The first freeze of the fall season is expected for the Owens Valley, with overnight lows dropping to between 27 and 32 degrees. A freeze watch is in effect through Wednesday morning for Bishop, Independence, Lone Pine and Olancha.
This story originally appeared in Los Angeles Times.
