LOS ANGELES (AP) — California’s power grid operator has asked for voluntary conservation of power because the extreme cold in much of the United States and Canada has caused a shortage of natural gas supplies to Southern California power plants.

The California Independent System Operator issued a so-called Flex Alert until 10 p.m. Thursday.

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The natural gas shortage is only impacting Southern California power plants, but authorities say statewide electricity and gas conservation will help free up both electricity and gas supplies.

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Flex Alerts are usually associated with power demands for cooling during California summers.

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