California’s grid operator is asking customers to limit electricity use during peak hours to help keep power flowing as a “heat dome” settles over the southwestern U.S.

But they were warned of this months ago.

The North American Electric Reliability Corporation (NERC) warned in May that California faced “significant risk of encountering operating conditions that could result in operating reserve shortfalls.”

Expected power demand is expected to outstrip California’s available generating capacity by about 5,000 megawatts on Tuesday, according to the California Independent System Operator (CAISO).

Why the lack of energy supplies? CAISO expects high demand for air conditioning during the heat wave to outstrip supply owing to “reduced electricity imports, tight natural gas supplies” and high wildfire risk.

The grid operator issued a flex alert to customers on Monday and began mobilizing all available generating capacity. But that’s not enough, and CAISO is asking residents and businesses to cut their power usage to prevent “rotating power outages.”

This is exactly what NERC warned about, based on CAISO’s own assessment earlier this year. NERC found an increased risk of rolling blackouts as “a result of lower hydro conditions and the retirement of 789 MW of dispatchable natural gas generation that had been available in prior summers to meet high load conditions.”

“Natural gas limitations and pipeline outages could exacerbate these conditions,” NERC found. (RELATED: New Study Claims Global Warming Will Cause Thousands More To Commit Suicide)

Tens of thousands of Californians lost power in early July when a heat wave sent temperatures soaring, recording new records in the Los Angeles area. Air conditioning use put too much strain on the grid, overloading electrical distribution.

CAISO asked customers “to conserve electricity especially during the late afternoon and evening when air conditioners typically are at peak use” for Tuesday and Wednesday when temperatures are expected to hit triple digits across much of southern California.

122°F in Palm Springs, California on Tuesday — location to watch for the most extreme temperatures across the Southwest U.S. beneath the #heatdome

Highs across the region are 10°-15°F above normal for mid-July and will set or tie daily record highs — including Phoenix at 116°F pic.twitter.com/3ypWj6XBOy — Ryan Maue | weathermodels.com (@RyanMaue) July 24, 2018

CAISO said customers “can help avoid power interruptions by turning off all unnecessary lights, using major appliances before 5 p.m. and after 9 p.m., and setting air conditioners to 78 degrees or higher.”

Follow Michael on Facebook and Twitter

Content created by The Daily Caller News Foundation is available without charge to any eligible news publisher that can provide a large audience. For licensing opportunities of our original content, please contact licensing@dailycallernewsfoundation.org.