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The Labor Day holiday weekend is shaping up to be ugly for the Bay Area, as temperatures head toward the 100s, threatening records across the region. Now residents cooped up inside amid the pandemic are being told to conserve energy, lest the state see a repeat of its recent rolling blackouts.
“The long story short is that there will be an oppressive heat wave,” National Weather Service meteorologist Drew Peterson said Thursday. “However, it won’t be as long as the last one.”
With the Bay Area still struggling to get back to clear skies after weeks of smoke-producing wildfires and stagnant air, authorities extended a record-setting string of Spare the Air alerts through at least Saturday, marking 19 consecutive days of warnings.
The hot air could lift temperatures in the far inland areas of the East Bay and in the Almaden Valley area of the South Bay into the 100s by Saturday, Peterson said. An excessive heat warning was declared Thursday, with authorities warning of an increased risk of heat-related illnesses and “little relief due to warm overnight lows” from 11 a.m. Saturday through 9 p.m. Monday.
The weather service also warned of “dangerous heat” up to 115 degrees on Sunday — temperatures are expected to hit 114 in Livermore, 110 in Concord, 106 in San Jose and 101 in Santa Cruz — as well as pronounced fire danger.
“That will be the day we will be looking for potential records,” Peterson said.
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The weather warning coincides with another bulletin — California’s Independent System Operator, which regulates the state’s energy, on Thursday issued a statewide Flex Alert. Consumers are being called on to conserve energy from 3 p.m. to 9 p.m. Saturday through Monday.
At a media briefing Thursday afternoon, ISO officials said they are asking for conservation but were not expecting to have to turn power off again.
“At this point we are not forecasting any blackouts,” said Eric Schmitt, vice president of operations for the ISO. “As we get closer and closer to each day, we’ll know more about the accuracy of our forecasts.”
Electricity demands are expected to hit similar levels to those that triggered two rolling blackouts three weeks ago when the last heat wave hit, but with supplies in better shape, the ISO is not anticipating the need to order utilities such as PG&E to curtail power deliveries.
However, Schmitt said residential customers should conserve in case power plants suffer outages or wildfires disrupt transmission lines.
He said state officials will be asking industry to also curb electricity use during afternoon and evening hours and to take actions such as running their emergency generators to feed more electricity onto the grid.
The ISO is recommending that residents set their air conditioning thermostats to 78 degrees, turn off any unnecessary lights and unplug all unused electrical devices. People also should close their blinds and drapes to keep heat out and avoid using any major appliances.
The wildfires exacerbated by the last round of near-record temperatures — after being sparked by the lightning that came with them, thankfully not in the forecast for this weekend — continue to burn, though fire crews keep making progress.
The three major Bay Area blazes — the SCU Lightning, LNU Lightning and CZU Lightning complex fires — have combined to burn 852,533 acres, about 1,332 square miles, according to the California Department of Forestry and Fire Protection. Seven people have died, and 3,702 buildings or homes have either been destroyed or damaged, according to the agency.
The SCU Lightning Complex fires, burning in Santa Clara, Alameda, Contra Costa, San Joaquin, Merced and Stanislaus counties, had burned 391,578 acres and were 78 percent contained by Thursday morning. The LNU Lightning Complex fires in Napa, Sonoma, Solano and Lake counties had burned 375,209 acres and were 81 percent contained. The CZU Lightning Complex fires in Santa Cruz and San Mateo counties had burned 85,746 acres and were 48 percent contained.
The heat won’t help the pollutant-filled skies around the region, officials said. Bay Area air-quality measurements Thursday showed fine-particulate levels from moderate all the way to the “unhealthy for all” range, depending on location.
The temperature rise, Peterson said, is being caused by a high-pressure system that has developed from the Pacific Northwest and is building over the Great Basin area of western Utah and Nevada, as well as parts of Idaho, Wyoming and Oregon. Peterson said the dome of the bubble created by the pressure is expected to be at a height that forecasters rarely see.
“It might be 600 decameters, which is an important level because we’ve seen that only two other times,” Peterson said. “The first time, it brought record heat to the Arctic Circle. The second time, it brought those 130-degree temperatures to Death Valley.”
The latter occurred during the heat wave last month that lasted in the Bay Area for about a week. This pattern shows a low-pressure trough that will begin to drop into the Great Basin by Monday and start to bring the thermometer down, Peterson said.
“At least,” Peterson said, “this heat wave won’t be as long in duration.”