California Storm, Atmospheric River A Flood, Debris Flow Danger, Including In Los Angeles Burn Areas

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A strong Pacific storm with an atmospheric river will continue to pummel California with a threat of flooding rain as feet of snow piles up in the Sierra Nevada through early Friday morning. Of particular concern is heavy rain raising the risk of flooding and debris flows in wildfire-scarred parts of the Los Angeles Basin.

Latest Storm Status

S​oaking rain and heavy Sierra snow are impacting much of California right now, as shown in the radar snapshot below. The Bay Area has seen multiple instances of road flooding this morning, including a couple vehicles reportedly stuck in floodwaters. Debris flows and rockslides have been reported from Santa Rosa to Salinas.

S​now and some ice are also falling across large proportions of the West, from Washington and Oregon, to the Rockies to the Desert Southwest's high country.

T​he National Weather Service has issued flood watches - shown in green on the map below - over much of California, except for the Mojave Desert and the San Joaquin Valley.

W​inter storm warnings are also in effect in the Sierra and Siskiyous of California, and high wind warnings are posted for parts of Northern California, including the Bay Area and central coast, and much of Southern California's high country from San Luis Obispo County the mountains above the Inland Empire.

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Storm T​iming

Through Friday Morning: This will be the peak impact of the storm, with bands of heavy rain, strong wind gusts, and heavy mountain snow.

-In Northern California, numerous showers and thunderstorms will likely flare up, with locally heavy rainfall.

-​In Southern California, the heaviest rain is expected Thursday night, diminishing to showers from north to south.

F​riday: Showers will linger over much of the state, before diminishing late in the day.

Rain, Snow Potential Impacts

T​his system is expected to be faster moving. That may cut down some of the precipitation totals compared to a slower-moving system, but we still expect some significant impacts.

M​uch of the state is likely to pick up at least a couple of inches of rain. Higher totals will occur in windward slopes of hills and mountains below elevations where snow will fall including the coastal ranges, Sierra foothills and Southern California.

F​lash flooding of typical urban trouble spots is likely. Some typical foothill and mountain trouble spots may also see flash flooding and rockslides.

The bigger concern is for the recent areas scarred by wildfires last month in Southern California, including the Eaton and Palisade fire scorched areas.

E​ven modest rainfall rates could trigger flows of mud, rocks, water and other debris that could be life-threatening near these burn areas. Stay away from these areas during the storm. If your property was not burned but you live near the burn area, be ready to evacuate at a moment's notice if urged to do so by local emergency management officials.

(​MORE: Why Debris Flows Are Dangerous)

M​ultiple feet of snowfall is likely in the Sierra, and up to 20 inches of snow is possible in the highest elevations of Southern California. This will likely make travel difficult in these areas. The snowy side of this storm has been named Winter Jett by The Weather Channel. Snow from this storm will eventually impact the Rockies, then the Midwest and Northeast Friday into this weekend.

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O​ther Impacts

-​Strong winds will accompany the heaviest rainfall near the cold front. Some higher gusts could down trees and knock out power, especially in soggy ground. These strong winds will also combine with falling snow to produce low visibility and dangerous travel over the high country.

-​ As we alluded to earlier, thunderstorms are also expected. Along with the threats of lightning and heavy rain, these thunderstorms could also dump hail that could briefly pile up on roads even in lower elevations. And these thunderstorms behind the cold front in California could even spawn a brief tornado, especially along the coast and in the Central Valley.

Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. Extreme and bizarre weather are his favorite topics. Reach out to him on X (formerly Twitter), Threads, Facebook and Bluesky.