Flash flood threat in California prompts evacuation warnings from multi-day atmospheric river

If this storm unfolds as forecast, this would be one of Los Angeles' wettest Novembers in the past 50 years.

SAN FRANCISCO – An atmospheric river has begun to slam California that is expected to bring days of heavy rain, strong wind gusts and potentially feet of mountain snow to the Golden State through early next week, ushering in the region's rainy season.

The storm system is forecast to bring several months' worth of rain to Southern California in the span of just a few days, while a flash flood threat covers the Bay Area and Northern California Thursday.

WHAT IS AN ATMOSPHERIC RIVER?

Santa Clara County urged drivers to use caution Thursday morning. Meanwhile, while heavy rain fell during the height of the Thursday morning rush in San Francisco

A brief ground stop was issued at San Francisco International Airport due to high winds Thursday afternoon.

Meanwhile, the City of Los Angeles issued evacuation warnings around the Hurst and Sunset Fire burn scars from January's devastating wildfires through Sunday morning. Evacuation orders were also issued for areas around Mandeville Canyon which was within the footprint of the Palisades Fire.

WHAT IS A WILDFIRE BURN SCAR AND HOW COULD THEY HAVE LASTING IMPACTS?

Video Thursday morning showed Los Angeles firefighters going door-to-door in Pasadena warning people living in high-risk homes.

According to the National Weather Service, ash from wildfires creates burn scars – a water-repellent coating that prevents the ground from absorbing water and causes the area to be predisposed to flash flooding and debris flows.

According to the FOX Forecast Center, rain is expected to sweep across coastal California and farther inland in the Central Valley Thursday.

NOAA's Weather Prediction Center issued two different Level 2 out of 4 flash flood threats Thursday, one that covers San Francisco and the Bay Area, the other covers Sacramento and parts of the Shasta Cascades, Sierra Nevadas and Gold Country.

Thunderstorms with lightning and strong wind gusts are possible as storms come onshore. 

KNOW YOUR FLOOD TERMINOLOGY: WHAT FLOOD WATCHES, WARNINGS AND EMERGENCIES REALLY MEAN

This graphic shows the flash flood threat.
(FOX Weather)


 

The more intense rain and the flood threat will move into Southern California Thursday night through the Friday morning commute. A second round is forecast to begin Friday evening.

All told, parts of the California coast, including San Francisco and Los Angeles, could see 3-5 inches of rain through Monday, with localized pockets of 5-8 inches of rain. The San Gabriel and Santa Monica ranges could also see 5-8 inches of rainfall.

A NEW TECH APPROACH TO FIGHTING WILDFIRES

This graphic shows expected rainfall.
(FOX Weather)


 

If this storm unfolds as forecast, this would be one of Los Angeles' wettest Novembers in the past 50 years.

DRIVING ON THE ICE AND DRIVING IN THE SNOW

This graphic shows winter weather alerts
(FOX Weather)


 

Meanwhile, winter weather alerts have been posted for the Sierras through Friday. Some of the highest mountain passes have already closed for the season.

Wind gusts along ridgetops in the Sierras could exceed 100 mph.

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