Longest and strongest Santa Ana winds bring fire danger to Southern California

Stock photo by Garry Knight via Flickr Creative Commons

Dry and gusty Santa Ana winds sweeping through Southern California are predicted to bring days of critical fire weather conditions.

Red Flag warnings by the National Weather Service began late Sunday and will last through Thursday.

Meteorologists say relative humidity levels will plunge into the single digits and teens. Officials have dedicated extra resources to fire-prone areas.

Forecasters say it could be the strongest and longest Santa Ana wind event so far this season, with gusts capable of bringing down tree branches and power lines.

Peak gusts are expected to range from about 40 mph to 60 mph in wind-prone areas. Isolated gusts could hit 80 mph in the mountains.

Emily Montanez with the L.A. County office of Emergency Services told KPCC's A Martinez that the areas most at risk for heavy winds include the Antelope Valley, Santa Clarita and the foothill and valley areas.

Montanez advised sheltering in place when the winds become severe, and keeping windows closed and doors locked. She recommended reviewing your family's emergency plan and being familiar with the location of gas supply valves, electrical switch boxes and water shut-off valves should utilities go down.

The wind may also down power lines. Brian Leventhal, spokesman for Southern California Edison, said if a power line falls on your car while you're driving, stay inside and use your cellphone to call 911. If you're outside, Leventhal said don’t step on downed power lines or in puddles that might be touching them. He cautioned residents to check for emergency supplies like flashlights and a battery-operated radio that could be helpful during a power outage and to not rely on candles for lighting.

During the red flag warning, residents might have to wait longer for power to come back on if it goes out.

Under normal conditions, power would automatically cycle back on after a momentary outage. But  during a red flag warning, utility workers will keep the power off until the faulty line can be inspected, Leventhal said.

“In cases where a fault is caused by physical damage to a wire such as a tree falling into the line during high winds, the patrol will find and correct that condition before energizing the circuit,” he said.

Much of Southern California Edison’s service territory, from Santa Barbara to Riverside and San Bernardino counties, is under that red flag warning.

The Santa Ana winds should be less extreme in the Los Angeles Basin. However, this windstorm, coming after the prolonged drought and hot summer, could take a toll on the city’s trees and power lines.  Years of dry weather have left trees more vulnerable to wind.

 “The roots get dried out and brittle and then as the rain soaks in, then the wind blows, it tends to blow those trees over, said Andrew Kendall, senior assistant general manager for power at L.A. Department of Water and Power.

Trees that drop branches or blow down cause power outages that can take hours or longer to repair.