A powerful storm with an atmospheric river threatens to bring life-threatening flooding and debris flow from Los Angeles wildfires burn scars.
The atmospheric river is forecast to unleash heavy downpours and wind on areas charred by last month’s fires, which were the most destructive in the county’s history.
Evacuation warnings were issued in places ravaged by the Palisades Fire including Mandeville Canyon due to concerns around debris flow. Warnings were also sent out for Trabuco Canyon and areas close to the Airport Fire burn scar.
The warnings went into effect at 7am and extend through Friday afternoon, and also apply to communities recovering from the Eaton, Bridge, Franklin, Hurst and Sunset fires.
Burn scar areas are more prone to debris flow because vegetation, which helps keep soil in place, has been replaced with loose rocks, ash and dirt, said Daniel Swain, a climate scientist for the University of California Agriculture and Natural Resources.
An atmospheric river is a long and narrow section in the air that transports water vapor outside of the tropics, according to the National Oceanic and Atmospheric Administration. They often release the vapor in the form of rain or snow.
The highest flash flooding risk in Southern California urban areas is ‘in and near recent burn scar areas’, according to the National Weather Service.
‘Those around recently burned areas should listen carefully to instructions from local officials,’ stated the service. ‘Flash flooding in burn scars will be life-threatening.’
A radar map from the service shows flash flood warning areas in green covering Los Angeles County including the burn scar areas, and much of the central and northern coastal areas except for the Mojave Desert and San Joaquin Valley.
Los Angeles County officials have urged residents to prepare for possible mandatory evacuation orders.
The storm is expected to strong winds capable of downing trees, causing power outages and delaying and canceling flights.
A statewide preparation effort has included 319,000 sandbags, erecting barriers across nearly 120 miles of Southern California, and more than 240 fire engines ready to respond across eight counties.
The atmospheric river is part of what AccuWeather called the ‘stormiest stretch of winter’ which began earlier this week and has affected 40 US states and 200million residents. A trio of storms has brought heavy rainfall to the West Coast, snow and sleet to the Midwest and Northeast and flooding in the Southeast.
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