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Southern California faces rare January wildfire threat from hot, dry and windy weather

The Washington Post logo The Washington Post 1/15/2021 Andrew Freedman, Diana Leonard
chart: The European model simulates an area of low pressure off the California coast on Jan. 18. (WeatherBell) The European model simulates an area of low pressure off the California coast on Jan. 18. (WeatherBell)

Record heat and strong winds have helped spread a smattering of brush fires in Southern California during the past few days, as periods of land-to-sea Santa Ana winds buffet that part of the state. The winds are bringing extremely dry air to an area that has yet to receive significant rain despite it being the heart of the rainy season.

The hot, dry and windy conditions are predicted to lead to dangerous fire weather conditions in Southern California for several more days.

The forecast for the next week is a forbidding one as a moderate to strong event unfolds between Monday and Wednesday. That event has forecasters at the National Weather Service concerned, given the drought conditions and clear signals in computer model guidance for winds that would be strong enough to cause extreme fire behavior should any blazes erupt.

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It is rare, though not unheard of, for Southern California to see wildfires in January. But firefighters and residents alike are weary as the state’s worst wildfire season on record, which occurred last year, never really ended. Instead, it just burned straight into 2021, and won’t end until significant rain and mountain snow arrives.

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Although a winter storm brought heavy rain to Southern California on Dec. 27-28, the region has been steadily drying out since then, and warm Santa Ana winds this week are helping to send temperatures into record territory.

“All the rain we’ve seen this year, it’s pretty much as if it didn’t happen,” said Alex Tardy, a meteorologist at the National Weather Service in San Diego.

He said that fires that broke out Thursday burned well, which indicates how much vegetation has dried out in the past 10 days, and temperatures in the 80s and 90s are boosting the fire threat.

After breaking records Thursday, temperatures in parts of Los Angeles County on Friday to climb to near 90, setting more records, with humidity percentages as low as the single digits. Downtown Los Angeles set a record high of 88 Friday, while Camarillo soared to 94, matching the location’s highest January temperature ever recorded and hottest temperature in the nation Friday. San Diego soared to 88, tying its highest January temperature ever observed.

This week’s hot, very dry and windy weather will lead to more rapid drying and set the stage for the bigger wind event next week.

On Friday, Santa Ana winds were gusting above 80 mph in the mountains of Southern California, about 55 mph in inland valleys and closer to 30 to 40 mph along the coast. Red Flag Warnings for dangerous fire weather conditions are in effect into Saturday.

The stage will be set for next week’s wind event starting Sunday night, when a deep dip, or trough, in the jet stream is expected to dive southward through California, spawning a swirling area of low pressure in the mid- to upper atmosphere by Monday morning. That low is likely to drift south to a position to the west of Los Angeles, or possibly further southwest. This low will help cool the atmosphere, bringing a much colder, and possibly slightly more humid, high wind event compared to many other Santa Anas, which can bring record heat.

map: A simulated surface map showing the ingredients in play to support a strong offshore wind event that could produce a significant fire weather event in California. (WeatherBell/Matthew Cappucci) A simulated surface map showing the ingredients in play to support a strong offshore wind event that could produce a significant fire weather event in California. (WeatherBell/Matthew Cappucci)

The weather pattern by Monday night looks to feature an area of low pressure in the Great Basin as well, and this one may merge with the one off the California coast. The European model shows the potential for wind gusts above 80 mph in some areas, the Weather Service forecast office in Los Angeles warned in a forecast discussion. The Weather Service office in San Diego had a similar warning in its forecast discussion Friday morning.

Strong Santa Ana windstorms are associated with some of the most damaging and deadly wildfires on record in Southern California, since they can cause fires to explode in size and quickly get out of control. Santa Ana winds are generally stronger and more frequent during the cooler months of November through February, but rains during the winter tend to squelch the fire potential.

“This has the potential to be a very serious and damaging wind event if all the factors come together,” forecasters wrote.

Joe Sirard, a meteorologist with the National Weather Service in Oxnard, said there is the potential for widespread damaging winds of at least 60 mph for Los Angeles and Ventura counties during the Monday to Wednesday period, with trees down and tree limbs falling into power lines.

map: The European model simulates strong wind gusts early next week in California, increasing the concern for fire danger. (WeatherBell) The European model simulates strong wind gusts early next week in California, increasing the concern for fire danger. (WeatherBell)

“People may wish to start preparing for these damaging winds and pay close attention to the National Weather Service over the holiday weekend,” he said.

While humidity next week may not be low enough to reach Red Flag Warning criteria, the very strong winds combined with very dry vegetation could still lead to rapid fire spread.

“It’s been so incredibly dry through the fall and winter that fuels are still incredibly dry,” he said. “If we’d had lots of rain in December and everything was all green now, I don’t think we’d think much about fire weather.”

Fire agencies have moved resources from Northern California in anticipation of the Southern California threat.

“We’re definitely in tune to what is expected and we want to make sure we are staffed up for this event,” said Thomas Shoots, fire captain and public information officer for Cal Fire San Diego.

Studies show that climate change is lengthening the fire season and leading to larger blazes than would otherwise occur. The 2018 National Climate Assessment, published by the Trump administration, projected that those trends will probably continue for several decades.

This story, first published Friday afternoon, was updated Saturday morning. Jason Samenow contributed to this article.

Diana Leonard is a science writer covering natural hazards. She holds master’s and PhD degrees in geography from the University of California at Berkeley, where she studied physical geography, natural hazards and climate science, and researched severe thunderstorm and tornado climatology.

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