The service described the event as the strongest of the season so far, with gusts of up to 70 mph forecast, along with humidity percentages into the single digits. Given the threat, Southern California utilities are considering cutting power to nearly 200,000 customers to prevent their equipment from sparking a wildfire.
The winds are expected to peak Wednesday evening into Thursday and could impact holiday travelers on major interstates that run through coastal mountains and mountain passes, according to the National Weather Service in San Diego.
“Those living near fire prone undeveloped areas, like the national forests, should make or review the family plan including what to take and evacuation routes in the event of an evacuation order is issued or a nearby wildfire threatens,” the Weather Service in Los Angeles wrote in a forecast discussion.
The renewed fire weather marks a turnaround from October’s atmospheric river, which brought extreme precipitation to northern California, but not quite enough rain to end the fire season farther south.
“October was very wet — unusually wet — and that bought us about three to four weeks,” said Alex Tardy, warning coordination meteorologist at the National Weather Service in San Diego.
However, November has been mostly dry and punctuated by several rounds of warm Santa Ana winds, which at times have brought record-breaking temperatures to the coast, quickly drying out vegetation and nearly erasing the benefits of earlier autumn rains.
The region saw a relatively quiet summer, even as bone-dry forests went up in flames in northern California and the Sierra.
“We expected quite a bit of fire activity in Southern California — it didn’t materialize,” Tardy said.
Fire meteorologists attribute the slower season in part to sparse growth from a dry winter and spring. The region did not see the type of “superbloom” of flowers, grasses and weeds that had helped to fuel recent fire seasons.
But explosive fires were possible where winds coincided with enough fuel to burn. That was evident in October’s Alisal Fire in Los Padres National Forest near Santa Barbara.
It was also apparent in the forests of the southern Sierra Nevada, which saw its driest water year on record, at only 9.9 inches. Nearly 20 percent of giant sequoia trees are estimated to have been killed by severe fire in the region over the past two years.
Outlooks lean dry for the weeks ahead
Santa Ana winds are most frequent and strongest during the winter months, and climate outlooks aren’t promising relief from the warm, dry weather just yet.
“The dice are loaded for dry conditions to continue for most of the West, especially for Southern California,” said Michael DeFlorio, a research analyst at the Center for Western Weather and Water Extremes at Scripps Institution of Oceanography in San Diego.
A number of forecast models are favoring dry weather for Southern California and the Southwest at least for the coming weeks, and potentially for the bulk of the winter season. These include models that predict atmospheric river activity and cutting-edge “machine learning” models developed at Scripps in collaboration with the NASA Jet Propulsion Laboratory, in addition to outlooks provided by the Climate Prediction Center.
The emerging La Niña, which is predicted to strengthen into the winter, is a key driver of the dry outlook, but it’s not the only one.
The current configuration of sea surface temperatures in the Pacific can promote high-pressure ridging that diverts the storm track. This kind of “blocking” pattern led to back-to-back dry winters in the West in 2020 and 2021. It’s also driving the dry spell right now, as strong storms are directed far to the north into Canada and the Pacific Northwest.
“We just keep seeing this persistent flow pattern of atmospheric river activity that is impacting British Columbia and the Pacific Northwest,” he said.
There are indications that the storm track could shift south later in the winter, bringing much wetter conditions to northern California, but confidence is low this far out.
“Currently, there is substantial uncertainty across different seasonal forecasting models for whether northern California will receive above average, below average or normal precipitation for this winter,” DeFlorio said.
Historic drought continues
October’s extreme atmospheric river provided a boost to reservoirs, and it gave parts of the state a good shot at achieving a normal amount of precipitation for the water year.
But an average water year would still leave the state in a historic drought.
“A normal or above-normal ‘wettish’ year is not enough,” said Alvar Escriva-Bou, a senior fellow at the Public Policy Institute of California’s Water Policy Center. “To get out of the danger zone, we need a wet year.”
That likely means sustained precipitation through the winter months to fill reservoirs enough to significantly move the drought needle.
A third dry year, he said, would lead to tangible water supply problems for cities, many more dry wells, fallowed farmland and more suffering for the environment, including river ecosystems and fish that need ample cold water to thrive.
The state finds itself in this position because of the fast-evolving nature of the 2020-21 drought, in which climate change-fueled conditions have caused unprecedented water stress.
“These two years have been almost catastrophic in terms of precipitation but also temperature,” he said.
Statewide, it was the third-driest water year since records began in 1895, he said. It was also the hottest summer on record in California and several Western states.
The brutal heat sapped moisture from already parched landscapes, accelerating drought impacts and fueling the summer’s extreme fires.
The good news is that wettest months of the rainy season are ahead, and there is plenty of time to reverse course.
“You never know in California. . . . There is a lot of uncertainty in what is actually going to happen,” Escriva-Bou said. “That’s why we say: Let’s plan for the worst, then we will minimize our potential risks.”