After a relatively calm day on the fire lines in Southern California, the National Weather Service’s Los Angeles office has issued a rare, if not unprecedented, “extreme red flag warning” for L.A. and Ventura counties tonight (see it here). The alert comes ahead of what authorities are calling “the most significant wind event over the past few years,” which is expected to begin around 11 p.m.

The warning runs through 6 a.m. Wednesday, and all mandatory evacuations ordered earlier in the week remain in effect.

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Note that an “extreme red flag warning” doesn’t actually exist in the Weather Service’s terminology, but the heightened danger apparently warranted such language.

The forecast calls for peak Santa Ana wind gusts of 50-70 mph with “isolated gusts to 80 mph possible in the Santa Monica and Los Angeles County mountains.” Noting the extremely dry 3%-10% humidity level, the Weather Service warns of “high potential for very rapid fire spread, long-range spotting and extreme fire behavior with any new fire ignitions.”

During a news conference Tuesday about the Getty Fire that broke out early Monday morning in the Sepulveda Pass, Los Angeles Mayor Eric Garcetti spoke of potentially dire circumstances overnight. After first offering some good news — that the fire is 15% contained, and there is “no open flame right now” — the mayor’s message turned ominous.

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“But — and this is the big ‘but,’ we have the most significant wind event in Los Angeles of the year that will be starting this evening around 11 o’clock.” he said. “It will peak at 3 a.m. but continue on through Thursday. … And there are still embers throughout this territory.”

Garcetti then compared the potential for fire tonight to a pair of historic L.A. firestorms. “I’m looking at 1961 [Bel-Air Fire], also the Mandeville Canyon fire in the 1970s — we are listening to our fire professionals who are making that call to continue to keep people evacuated in that mandatory-evacuation area. All it takes is one ember … and we could see new fire or fires emerge in this area.”

The Santa Ana wind-driven fire that devastated the tony Bel-Air community in November 1961 destroyed more than 480 homes and charred some 16,900 acres. The 1978 Mandeville Canyon fire burned from Agoura in the West San Fernando Valley through the canyons to Malibu and the ocean, costing 230 homes.

Meanwhile, the Los Angeles Fire Department noted that the city’s red-flag parking restrictions took effect at 8 p.m. Tuesday and, “due to the expected severe wind event, the parking restrictions will remain in effect until further notice.” That means authorities will “remove vehicles that create a hazardous condition on Red Flag Days.”

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