AccuWeather long-term Northern California forecast includes potential for dry lightning, continued drought next fall

With more than 1.1 million acres across the drought-afflicted West already charred, 2022 is shaping up to be another year of extremely intense fire activity.

But with the release Wednesday of its official 2022 Wildfire Season Forecast, AccuWeather forecasting company has added a couple of gut punches to this year’s outlook for flame-battered Northern California and the North Bay region.

Chief among them is the prospect of dry lightning associated with tropical storms off the coast of Mexico in mid- to late-summer and continued dry La Niña conditions heading into fall and early winter — and perhaps beyond.

That could mean a potential fourth year of abnormally low rainfall and the threat of lightning-sparked wildfires like those in August 2020 that ravaged the region and much of California.

Things could change, but at this point in early May, the signs are ominous.

“I wish I had better news,” Chief AccuWeather Meteorologist Jonathan Porter said Wednesday in an interview with The Press Democrat.

Anyone awake already knows that the entire Western U.S. is under threat of severe wildfires on the heels of a record-breaking year that blackened at least 7.1 million acres in 2021.

But for Sonoma County and its neighbors, 2021 was largely a chance to breathe after six years of seasonal catastrophes that included the 2015 Valley fire in Lake County and the 2017 North Bay Firestorm.

The Western half of the country is in the midst of a megadrought that has made the past 22 years the driest stretch of time in at least 1,200 years, with climate change and rising temperatures contributing to severe water shortages and aridification of the landscape.

Three years of lower-than-average rainfall in Sonoma County and neighboring counties has left reservoirs wanting, withdrawals from the Russian River watershed curtailed, consumers forced to conserve and vegetation increasingly parched.

And even some recent late-season rain that dampened the region last month mostly just encouraged grasses and brush to bloom, creating more wildfire fuel, Porter said.

“That vegetation that can bloom up then starts drying out, and the problem is that’s more fuel for later in the season,” he said.

Local fire officials say existing conditions make it all the more critical for residents to exercise extreme caution with anything that has the potential to cast a spark or release flame.

But in the case of lightning, there’s little to do, as those who lived through August 2020 know.

That year, hundreds of lightning-sparked wildfires spread across California, merging into wildfire “complexes” like the LNU Lightning Complex, which included the Walbridge, Meyers and Hennessey fires and burned 363,220 acres in Sonoma, Napa, Solano, Lake and Colusa counties. It remains the sixth-largest fire in state history.

The August Complex of 2020 is the largest in California, burning more than a million acres over nearly three months in Mendocino, Humboldt, Lake, Trinity, Glenn, Colusa and Tehama counties.

The SCU Lightning Complex in the Santa Clara County area and the North Complex in Butte and Plumas counties, as well as the CZU Complex in Santa Cruz and San Mateo counties, all erupted the same weekend in August 2020.

“This year we’re concerned it could be a few more of those episodes than last year, and once again it looks like another hot summer that is going to again result in the drought conditions continuing to intensify into the summer,” Porter said.

He characterized the chances of summer dry lightning and extended drought toward the end of the year as “moderate to likely risks, based on what we’re seeing.”

However, Daniel Swain, a climate scientist and highly consulted weather blogger with UCLA, cast doubt on such long-term predictions, saying via email there was “little to no predictability of dry lightning events in California out beyond a week or so.”

Though, if thunderstorms do occur the stakes would be extremely high “given the exceptionally dry state of the forests due to long-term drought, so it’s a considerable concern,” he continued.

He also noted that there are no signs that the La Niña oceanic conditions are trending toward a wetter El Niño, and thus that it’s likely to persist “through summer at least, and perhaps into autumn.” But it’s “still too early to make any kind of confident prediction about next winter,” he wrote.

The National Weather Service already has predicted a 50% to 55% chance of existing dry La Niña conditions persisting into the fall, but AccuWeather said it anticipates it extending beyond fall, with the jet stream looping north of California and sending moisture northward, closer to the Pacific Northwest.

“If that persists, then it can be a problem again heading into the wildfire season next year,” he said.

You can reach Staff Writer Mary Callahan at 707-521-5249 or mary.callahan@pressdemocrat.com. On Twitter @MaryCallahanB.