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Scattered pockets of northern Utah remained plagued by power outages on Friday, the day after strong winds lashed the region and electrical services to an estimated 85,000 Rocky Mountain Power customers were disrupted.

Rocky Mountain Power began scrambling repair crews about 11 p.m., shortly after a cascade of outages struck areas of downtown Salt Lake City, North Salt Lake, South Salt Lake, West Valley City, Magna, Bountiful, Centerville and Tooele.

By dawn Friday, most customers had been restored to the power grid, though isolated pockets — including some traffic lights in Salt Lake City — remained down. Police cautioned motorists to treat darkened intersections as "four-way" stops.

As of 7:45 a.m. Friday, RMP spokesman Paul Murphy said, the utility had no active reports of outages, though it encouraged any clients still without electricity to call for service at 877-508-5088.

While the windstorms that blew through much of the Wasatch Front late Thursday afternoon and evening were suspected as factors in the outages, RMP still had not officially determined causes for the loss of service, roughly affecting customers in zip codes 84044, 84102, 84103, 84128 and 84074.

The outages were not considered connected to one that forced closure of Alta High School in Sandy Friday mid-morning. Canyons School District spokesman Jeff Haney said a transformer in front of the school, at 11055 S. 1000 East, blew out, and when it was learned repairs would not be complete until the afternoon, the decision was made to send students home.

The outages were not related to some reports of flames flaring from oil refineries in the North Salt Lake area Thursday night. Those flames reportedly were part of normal operations.

Refineries generally have towers or stacks that have a constant flame burning at the top. Such "flare stacks" are designed as safety devices, occasionally igniting vented hydrocarbons in what can be a dramatic, nighttime display.

Twitter: @remims