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Southern California Well-Versed in Atmospheric River Response

With potentially record-breaking rainfall predicted for Sunday and Monday, Los Angeles and its neighboring counties were well-prepared, having endured a storm of similar magnitude in January 2023.

Flooding and damage from atmospheric river storm in Southern California
Los Angeles, CA - February 05: A man attempts to sweep mud and debris from the driveway of his Beverly Crest home on N. Beverly Glen Blvd. after an atmospheric river unleashed heavy rain, debris flows, mudslides and flooding in Southern California Monday, Feb. 5, 2024.
(Allen J. Schaben / Los Angeles Times)
Californians have become acquainted in recent years with the massive rainstorms now widely known as atmospheric rivers, and though parts of the state are still reeling from the record-breaking rainfall, the challenges of response and recovery from these storms have become almost second nature.

On Sunday, potentially record-breaking rain was forecast for the Southern California area, including more than 10 inches in Los Angeles and up to 15 inches at some of the higher peaks. Santa Barbara and Ventura counties, hit violently hard last year by an atmospheric river, were again in the crosshairs.

Los Angeles meteorologist Jim Boyd said the rain was coming down and that more was on the way with the densest rainfall hitting Ventura County.

Ventura County, which sustained rising flood waters up to 25 feet, evacuation orders and nearly 20 rescues in the January 2023 flooding, on Monday was assessing damage from 8 inches of rain in a 24-hour period in certain areas.

Local first responders and emergency managers acted early in anticipation of another violent event. The county had evacuation orders in some of the most flood-prone areas and warnings in others; ultimately there were no injuries or rescues but plenty of cooperation.

“I have to say, we were expecting pretty big rainfall rates [this week], which we did get, and so far we do have a shelter open with a few occupants,” said Kim Dellacort, public information officer for the Ventura County Sheriff’s Office of Emergency Services.

“As emergency managers, we know our area and we know that when the weather forecast predicts a certain threshold, we need to stage certain resources and take actions to plan with our operational area partners.”

Dellacort said it’s difficult to predict the outcome of such an intense rain event and even with the best action plans there are situations that are hard to mitigate. “We were prepared last year of course, but not able to predict a future in that a road would wash away at Matilija Canyon. But we were on hand to help facilitate any evacuations that were needed last year as well.”

Santa Barbara County is also well acquainted with the atmospheric river. Last year’s January storm prompted President Joe Biden and California Gov. Gavin Newsom to exercise emergency proclamations for the area, and the county spent $100 million repairing damage from the event.

Jackie Ruiz, Emergency Preparedness Communications and Outreach Coordinator for Santa Barbara County, said the region is still assessing the storm’s impact.

“While the worst has passed, more rain is expected with a flood watch in place through [Tuesday],” she said. “Safety precautions continue to be emphasized, with active responders clearing downed trees and power lines to ensure community safety.”

Winds in the area hit gusts of 50 to 80 miles per hour and rainfall registered as much as 3.6 inches in just one hour.

In Los Angeles, the 7.03 inches of rain that fell Sunday and Monday go on record as the third-most for a two-day period for the city. First responders were busy as at least 307 mudslides were triggered by the rainfall.
Jim McKay is the editor of Emergency Management magazine.