Never used before, ‘purple’ fire warning in So. California due to Santa Ana winds

LOS ANGELES -- Southern Californians already dealing with a siege of destructive wildfires were warned to be ready for extreme fire potential early Thursday, but conditions turned out to be less dire than predicted even though strong Santa Ana winds were blowing.

Ken Pimlott, director of the California Department of Forestry and Fire Protection, had said Wednesday that a color-coded danger scale had reached purple, which was never used previously, and winds could reach 80 mph.

Later, the California Office of Emergency Services transmitted a region-wide emergency alert to mobile phones in Los Angeles and six other counties: "Strong winds overnight creating extreme fire danger. Stay alert. Listen to authorities."

The purple that Pimlott referred to is part of the "Santa Ana Wildfire Threat Index " produced by the U.S. Forest Service, the National Interagency Coordination Center's Predictive Services and other collaborators to categorize Santa Anas according to fire potential.

The threat index uses a predictive model that incorporates moisture levels of dead and live vegetation and weather models, including wind speeds and atmospheric moisture, to produce a six-day forecast for potentially large fires. The result is then compared to climate data and the historical record of fires to create the rating.

On Thursday, the National Weather Service said there was a "burst" of winds Wednesday night but it subsided, and it appeared models may have "over forecast" Thursday's wind event. Nonetheless, parts of Southern California still were buffeted by strong winds, including 88 mph in San Diego County and 85 mph in Ventura County, where the largest fire is burning.