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SAN FRANCISCO – Pacific Gas & Electric Co. on Saturday began cutting power to 940,000 customers – 90,000 more than initially planned – in a desperate effort to prevent catastrophic wildfires that could be fanned by exceptionally powerful winds.

The North Bay and northern Sierra foothills were among the first areas to lose power about 5 p.m., said Mark Quinlan, the utility’s incident commander for the public safety power shutoff. Parts of the East Bay and South Bay were expected to follow suit at 8 p.m. Quinlan said the utility plans to continue shutting off the power in waves through Sunday evening, ultimately affecting well over 2 million residents in 36 counties.

And possibly before all that power is restored, yet another round of shutoffs could be activated. Andy Vesey, a PG&E executive who oversees the electric operations, said a fourth series of shutoffs could come as early as next week.

“We’re not out of the woods yet,” Vesey said.

PG&E said it expanded its map of affected customers in some areas because of “historic wind event” expected to arrive Saturday evening

#PSPS UPDATE: 2nd PSPS Impact Expands by 90k Customers
• Total projected impact now 940k in portions of 36 counties
• Power to be shutoff for safety in 6 zones starting @ approx 2PM today (weather dependent)
• Address look-up: https://t.co/AUFB81ZXtQ pic.twitter.com/mBxz5dhc78

— PG&E (@PGE4Me) October 26, 2019

“This wind event is forecast to be the most serious weather situation that Northern and Central California has experienced in recent memory,” said Michael Lewis, PG&E’s senior vice president of electric operations. “We would only take this decision for one reason – to help reduce catastrophic wildfire risk to our customers and communities. There is no compromising the safety of our customers, which is our most important responsibility.”

While the number of people projected to lose power across PG&E’s coverage area has increased, the blackout area in many Bay Area counties slightly shrunk in the utility’s latest estimates.

PG&E said Saturday that 57,002 customers in Alameda County, 48,058 in Contra Costa County, 57,218 in San Mateo County and 27,094 in Santa Clara County are expected to lose power.

That’s just over 9,000 fewer total customers across those four counties than had been projected to see blackouts in plans released Friday. Most of those getting a reprieve were in San Mateo County, where the planned outage is set to affect 7,714 fewer customers.

Officials recommended residents use the address search tool on the PG&E website to find out whether their homes will lose electricity. That feature is more precise than the maps of outage areas PG&E has produced.

Meanwhile, hundreds of people in parts of Piedmont and Oakland’s Montclair district who were already bracing for the shutoff were surprised to find their power go out briefly late Saturday morning, hours before what they expected. But that outage was not connected to the planned power shutoff, according to PG&E.

A city of Oakland spokesman said officials were monitoring reports of isolated outages, which also included flashing red lights on 35th Avenue and MacArthur Boulevard.

The utility’s updated plans called for the shutoffs to roll out across the state starting at 5 p.m. Saturday in 12 counties encompassing the Sierra Nevada and parts of the Central Valley, as well as North Bay counties including Marin, Napa, Solano and Sonoma.

Customers Alameda, Contra Costa, Monterey, San Benito, San Mateo, Santa Clara and Santa Cruz counties were told they would lose power starting at 8 p.m.

The utility was also poised to cut power on the North Coast at 9 p.m. and in the southern Sierra foothills at midnight.

A final phase, starting at 9 p.m. Sunday, will affect fewer than 1,000 customers in Kern County, although the utility said it was also eyeing potential shutoffs in Madera and Fresno counties.

Although PG&E faced withering criticism from customers and public officials, including Gov. Gavin Newsom, for a similar shutoff across much of the Bay Area and Northern California less than three weeks ago, this outage is set to be even bigger.

Weather models indicate the combination of wind and heat this weekend could be the most powerful in California in years, with dry offshore winds expected to gust between 45 and 60 mph. Peak gusts between 65 and 80 mph are possible at higher elevations.

“It has the potential to be one of the strongest in the last several years,” PG&E principal meteorologist Scott Strenfel said in a statement. “It’s also likely to be longer than recent wind events, which have lasted about 12 hours or less.”

Customers should prepare for a shutoff lasting at least two days after the winds die down, according to the company.

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PG&E won’t restore power until inspections of de-energized lines are completed and any damage to the system is repaired. The utility also has requested mutual aid from 1,000 workers from other energy companies, including ATCO Energy in Alberta, Canada; Xcel Energy in Minnesota; and Florida Power & Light. Those crews are expected to be staged and in place to do repairs by Sunday, according to the company.

In San Jose, where the outages are expected to be less widespread than they were during the shutoff earlier this month, the city will make four community centers available from noon to 7 p.m. Saturday and Sunday for residents affected by the blackouts, Mayor Sam Liccardo said.

The outages in the southern and eastern parts of the city are expected to affect 98,000 residents and 1,900 businesses — roughly half as many as lost power during the last shutoff.

The Berryesa, Camden, Evergreen and South Side community centers will offer snacks and water, as well as charging stations for phones and medical devices. They will not offer medical care, but Liccardo said emergency personnel will continue operating as usual, at least for the foreseeable future.

The centers will be open during normal business operating hours on Monday and will continue providing services to impacted residents.

“We believe that although the shutoffs are expected to be much shorter, everyone should be prepared for an extended shutoff,” he said.

Liccardo urged affected residents to stay at home and avoid driving, biking or walking outside in the dark.

PG&E is opening a similar center during daylight hours in Alameda County at Merritt College in Oakland, where affected residents can use the restroom, get water and charge their mobile devices.

The Oakland Fire Department will also have roving fire patrols in the Oakland hills to monitor for any fires, according to a city news release.

“We are anticipating historically strong winds, the strongest we’ve seen in years,” Oakland fire Chief Darin White said. “Although the most severe local threat is in the East Bay hills, a rapidly spreading wildfire could have widespread impact across the city.”

There is a red flag warning in effect in the East Bay hills from 8 p.m. Saturday to 11 a.m. Monday, according to the release. Some 23,000 Oakland residents could be affected by the outages, according to PG&E.

An estimated 195,000 residents could be affected by the outages in San Mateo County,  according to a county news release. The county’s health department also reached out to vulnerable residents and those dependent on medical equipment.

The San Mateo Medical Center and all clinics except the Coastside Clinic were expected to remain open, according to the release.

In San Jose, government officials expressed frustration with the outages, which they said are disruptive to residents, as well as to city employees that have to work during the weekend. Similar outages earlier this month cost the city an estimated half a million dollars.

“Obviously this is very frustrating for us all as we’re having to deal with this and obviously it’s part of a bigger conversation with PG&E,” Sykes said.

Liccardo, who had previously indicated he would like to explore moving to a city-owned utility, likewise said the shutoffs must not become routine.

“This cannot be the new normal,” he said. “We need to have better solutions.”