Fires were breaking out across Southern California on Wednesday, fueled by intense winds.
By midday, the region was facing peak extreme fire weather, with winds of up to 78 mph at Boney Peak in the Santa Monica Mountains in Ventura County, while relative humidity fell to rock bottom, clocking in at zero at Mt. Wilson in the San Gabriel Mountains and peaks in the Santa Ynez Mountains and the Los Padres National Forest, National Weather Service meteorologist Lisa Phillips said.
Camarillo recorded a gust of 55 mph at its airport, and television crews showed big rigs on a freeway knocked over by gusts in Fontana, which sits just south of a powerful Santa Ana wind corridor, the Cajon Pass.
The air was exceedingly dry throughout Ventura County; at Sinaloa Lake, relative humidity was at 8%, while Moorpark clocked in at 7%. Humidity of 15% to 20% is considered quite dry.
Climatologist Bill Patzert said the source of the winds is coming from a high-pressure cold front parked over the Utah area, and that’s extending cold Santa Ana winds into California. Because the air is so cold, it’s also very heavy.
“So it accelerates more rapidly, because it’s so heavy coming through these passes — that’s why you’re getting these extreme wind speeds,” Patzert said.
Colder Santa Ana winds can in some ways be more dangerous than warmer Santa Anas, Patzert said, especially if the high-pressure system is stationary.
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The National Weather Service issued a rare “extreme red-flag warning” through Thursday evening, saying winds could top 80 mph and be the strongest in more than a decade. The wind event is expected to last 30 hours.
“This is the worst since we had an event in October 2007,” National Weather Service meteorologist Tom Fisher said. “Don’t let your guard down.”
During the 2007 weather pattern, a series of fires broke out across Southern California and burned more than 198,000 acres, destroying 1,500 homes, injuring 40 firefighters and causing two deaths. The most significant of those fires was the Witch fire in San Diego County, which ultimately led the region’s major utility to spend about $1.5 billion to update its grid to avoid sparking future fires.
On Wednesday, multiple fires sprouted amid the strong winds, including the Easy fire, which started shortly after 6 a.m. in Simi Valley and threatened the Ronald Reagan Presidential Library. Elsewhere, fires erupted in Calabasas and in Riverside and Kern counties.