Extreme fire risk — fierce winds forecast
Extremely risky fire weather is expected this weekend, frighteningly reminiscent of the conditions that have caused some of the worst blazes Northern California has seen in recent years to leap over hills and send people fleeing for their lives.
Pacific Gas and Electric Co. warned that power shutoffs intended to prevent fires from sparking are possible Sunday through Tuesday and could impact a wide swath of its service territory. Dry, windy conditions forecast for that period prompted National Weather Service officials to issue a fire weather watch from 11 a. m. Sunday through 11 a. m. Tuesday.
Weather service officials said these conditions and “poor humidity recoveries” cause an “increased risk of new wildfire starts and rapid spread.” The fire weather watch is for the North Bay mountains and valleys, East
Bay hills and valleys, Diablo Range and Santa Cruz Mountains. A red flag warning has not been issued for the event yet, though a separate one expires Friday morning.
Will Pi, a meteorologist with the National Weather Service, said the North and East Bay hills could see winds of 80 to 100 mph. In the valleys and along the coast, winds could reach 30 to 50 mph, he said.
“This will likely be strongest & most widespread offshore wind event of season, & is reminiscent of extreme events in 2019 & 2017,” UCLA climate scientist Daniel Swain wrote on Twitter. “Hardesthit areas appear to be west slopes of Sierra Nevada ( gusts of 70+ mph) & SF Bay Area ( widespread gusts 4050mph; higher in hills).
“These truly extreme upcoming fire weather conditions, combined with recorddry vegetation for time of year, portend a dangerous period ahead,” Swain said. “I would anticipate fairly widespread Public Safety Power Shutoffs by electrical utilities on Sun/ Mon to prevent ignitions.”
The Bay Area got a brief reprieve from shutoffs Thursday: PG& E removed all Bay
Area counties from its list of areas facing power cuts. Approximately 4,200 homes and businesses across the Bay Area had been expected to lose power Thursday and Friday, but the utility canceled those blackouts “due to a change in weather conditions,” according to a PG& E spokesperson. Now, just 32,000 PG& E customers across Northern California face blackouts, down from 53,000 as originally estimated.
Winds across the Bay Area remained “borderline critical” Wednesday but did not reach speeds that would “bring down power lines or trees,” said National Weather Service meteorologist Roger Gass. It remains unclear whether Sunday’s forecast winds would reach that capacity, he added.
But the focus is shifting to the weekend and early next week, when the danger is expected to sharply increase, with the Bay Area as one of the main areas of danger.
The National Weather Service said Thursday that critical fire weather conditions will return late Saturday night into Monday, with the strongest winds peaking overnight Sunday. The agency’s Sacramento office warned of “widespread extreme fire weather conditions” beginning Sunday, with potential gusts of more than 70 mph in some areas.
Humidity is likely to be “exceptionally low,” according to Swain, who said that the offshore winds starting Sunday will be accompanied by cold weather, as “temperatures will drop precipitously ( especially in mountains).”
PG& E said Thursday that the risk of shutoffs Sunday to Tuesday is “elevated” across most of its territory, including the Bay Area. The utility expects to have more information Friday or Saturday on cities and counties that may be affected.
Nora Mishanec and Shwanika Narayan are San Francisco Chronicle staff writers. Email: nora. mishanec@ sfchronicle. com, shwanika. narayan@ sfchronicle. com Twitter: @ NMishanec, @ Shwanika