Extraordinarily powerful winds and gusts — of up to 99 mph — have been reported as three major wildfires burn homes and businesses in Los Angeles County on Wednesday morning.
The National Weather Service reported a gust of 99 mph near Altadena at 10:20 p.m. Tuesday; 98 mph near Woodland Hills at 9:37 p.m.; and 84 mph at Hollywood Burbank Airport at 8:30 p.m.
Officials said this was not a typical Santa Ana wind event, though it is indeed bringing dry, offshore winds to the area. Forecasters warned the event could be accompanied by a weather phenomenon that can cause short-lived but extremely destructive winds; its effects were expected to be felt particularly in the San Gabriel foothills and valleys.
The “mountain wave wind” activity occurs when gusts rapidly drop down mountain slopes, then gain strength upon hitting the flat landscape, causing “brief bursts of very strong, dangerous winds,” said NWS meteorologist Rich Thompson before the first of three fires in the L.A. region, the Palisades fire, broke out Tuesday.
He said this could be the strongest such wind event since the 2011 windstorm that caused serious damage in Pasadena, Altadena and other San Gabriel Valley neighborhoods, knocking out power for days for more than 400,000 people. The 2011 windstorm caused at least $40 million in damage, according to a preliminary estimate.
“If it does develop, it can cause very specific damage,” Thompson said before this week’s fires broke out. “Imagine like a wave in the water. … Those winds kind of go down slope, then just hit the surface and get very strong.”
On Tuesday night, increasing winds made an air attack against the wildfires impossible. Fearsome winds forced crews to ground aircraft in the battle against the Palisades fire shortly before 8 p.m. Tuesday.
About two hours earlier, the Eaton fire broke out in the hills above Altadena near Eaton Canyon. Strong winds led officials to suspend air coverage of the Eaton fire for the evening, officials said at 8:45 p.m.
The lack of rain has extended the fire season in Southern California. Since Oct. 1, the beginning of the water year, downtown Los Angeles has received 0.16 inches of rain — a tiny fraction of the 4.64 inches that downtown gets, on average, by this point in the season.
By contrast, Northern California hasn’t faced such fire weather, with rainfall at above-average levels. Downtown San Francisco has received 10.39 inches of rain since Oct. 1 — above the 9.29 inches of rainfall the city gets on average by this point in the season.
“Southern California has experienced a particularly hot summer, followed by almost no precipitation during what is normally our wet season,” said Alex Hall, director of the UCLA Center for Climate Science. “And all of this comes on the heels of two very rainy years, which means there is plenty of fuel for potential wildfires.”
Extreme fire conditions were expected to continue through the middle of Wednesday afternoon, the weather service said after midnight Wednesday. “Any wildfires that start will likely spread rapidly with extreme fire behavior,” the weather service said.
Another Santa Ana wind event is expected for Friday. But it is expected to be “more typical,” the NWS said, with winds forecast to come from the northeast “focused along the typical Santa Ana wind corridor, from the Santa Clarita Valley to Point Mugu. … The downsloping winds will also reduce the humidities and increase the fire danger.”
The weather service warned that winds “will be gusty and erratic, with lulls between gusts.”
Ahead of Tuesday’s fires, the National Weather Service issued a “particularly dangerous situation” red flag warning, alerting of extreme fire weather (abbreviated as a PDS). The weather service issued the same warning about a month ago — when the Franklin fire ignited and spread rapidly in the Malibu area. It went on to burn more than 4,037 acres, destroying 20 structures and damaging 28 more.
An infographic from the National Weather Service explaining a particularly dangerous situation red flag warning.
(National Weather Service)
And a month before that, a particularly dangerous situation red flag warning was issued on election day. The following day, on Nov. 6, the Mountain fire ignited in Ventura County and, whipped by powerful winds, razed more than 240 buildings. It became the third-most-destructive wildfire in Southern California since 2013, and burned 19,904 acres.
This type of red flag warning is expected to occur, on average, once every three to five years. But the National Weather Service office in Oxnard has now issued such a warning three times in just this fire season. The office issues forecasts for L.A. County, as well as Ventura, Santa Barbara and San Luis Obispo counties.
Before November, the last time a particularly dangerous situation red flag warning was issued by the National Weather Service office for L.A. and Ventura counties was in 2020, the first year those alerts existed for the region. That type of warning was issued twice in 2020 — once in October and again in December.
