Dry winds let up, but fire season isn’t over
No more extreme weather in the forecast — neither is rain in coming weeks
The latest wildfire scare appears to be over as offshore winds subside in Northern California, but a lingering pattern of hot, dry weather suggests the threat of new blazes remains for firefighters and beleaguered residents.
No more extreme fire weather is expected in the next couple of weeks, climate scientists and meteorologists said, but there isn’t any rain in the forecast either, and that troubling scenario could linger throughout much of November, possibly even past Thanksgiving.
“There is really no relief on the horizon,” said Daniel Swain, a climate scientist at UCLA and the National Center for Atmospheric Research. “I see no rain or mountain snow looking as far out as mid-November. The question is, are we still going to be talking about wildfires on Thanksgiving this year?”
The region breathed a collective sigh of relief Tuesday when no new major wildfires erupted as strong, gusting winds swept across Northern California over the past couple of days. Sensors measured wind speeds of 78 mph above Mount
St. Helena early Tuesday in the North Bay’s Mayacamas Mountains. The East Bay hills and the Diablo Range also saw gusts up to 60 mph at dawn, the kind of weather that has led to several catastrophic fires over the past few years.
The strongest winds of the year prompted PG& E to preemptively shut off power to 345,000 homes and businesses in the Bay Area, a gambit that ruffled a few feathers but appeared to head off disaster. PG& E officials said there were at least 13 examples of weather damage to equipment, including fallen power lines and trees that hit power lines, that might have started fires had the power not been shut off.
Power had been restored to 228,000 customers by Tuesday morning.
“We had the weather, we had the fuels, but luckily we did not get the ignition,” said Drew Peterson, a National Weather Service meteorologist.
But that doesn’t mean there weren’t any problems. Gov. Gavin Newsom said during a news conference Tuesday that 42 wildfires were ignited and 90,710 people were evacuated, mostly in Southern California, during the 24 hours ending Tuesday morning.
Fourteen of those fires were still burning Tuesday, including two fires that erupted in Orange County. Some of the major fires that erupted during the August lightning storms are still burning within their containment lines.
Although red flag warnings in the East Bay and North Bay were lifted at 5 p. m. Tuesday, dry vegetation and extremely low humidity remains, leaving pretty much every place in California ripe for the kinds of autumn fires that have plagued the state over the past decade.
“The risk remains elevated until we’ve received substantial precipitation,” said Noah Diffenbaugh, a climate scientist at Stanford University. “The current weather outlooks are not indicative of significant precipitation over the next couple of weeks. The combination of hot conditions in the summer and early fall followed by the delayed onset to the rainy season suggests sustained wildfire risk.”
Autumn is typically when strong offshore winds blow down the mountains toward the coast. Without rain to dampen the dry grasses, these winds can whip up flames into dangerous conflagrations. That’s because the vegetation has had all summer to dry out.
And this year is worse. August and September each recorded the hottest average temperature for those months in California history, and October may also beat the standard, Swain said. The high heat and extremely low humidity “are just sucking whatever moistures are left in the vegetation,” he said.
It is part of a growing pattern. Some of the largest and most destructive fires in California history have occurred in the fall season, including the
Camp Fire, which destroyed the Butte County town of Paradise in November 2018, and the Tubbs Fire, which raged into Santa Rosa, destroying thousands of homes, in October 2017.
“Historically if you got the rains in October or early November you would head it off at the pass,” Swain said. “So it’s not that the winds are changing. It’s just that everything leading up to the winds is changing.”
So far this year, 31 people have died and 9,358 structures have been destroyed in wildfires. Five of the top 10 largest fires in California history have struck this year. The largest fire ever, the August Complex, in Mendocino, Humboldt, Trinity, Tehama, Glenn, Lake and Colusa counties, is now 93% contained. The 374,000acre Creek Complex, in Fresno and Madera counties, was 63% contained Tuesday.
With so much acreage burned, California officials are worried that the rains, whenever they do come, could cause serious erosion and mudslides. The winter season is, however, unlikely to bring much relief. A strong La Niña weather pattern is expected, which usually means less rain and snow in the winter.
“If we had some rain soon, it would be a relief to everybody, but a La Niña winter makes it less likely to get that,” said LeRoy Westerling, a climate and fire scientist at UC Merced, who published studies in 2006 and 2016 that documented how California’s fire season is starting earlier and ending later on average than it ever has.
“This is already a recordbreaking season, and if we get more wind we could still have more fires, so we are not out of the woods yet,” he said. “Until we get those seasonending events that really wet things down, it’s not under control, and it won’t be.”
A study published in August by scientists at Stanford’s Woods Institute for the Environment found that the number of extreme wildfire weather days in California in the fall has more than doubled in the last four decades.
“What that means is that when these strong wind events occur, they are more likely to occur in these dry vegetation conditions,” said Diffenbaugh, who led the study. “The reality is that climate change is elevating the risk of extreme wildfire conditions that we know have contributed to large destructive fires in recent years.”
All of it had been predicted over the past few decades by climate scientists, for whom the refusal of many in government to reduce carbon emissions or do anything about climate change is a continuing source of angst.
“It’s immensely frustrating,” Swain said. “2020 has been exhausting on so many levels, but for scientists who study climatology and wildfire, it’s very frustrating, because this was not unforeseeable.”