Power conservation urged as California broils

LOS ANGELES — California energy authorities urged voluntary conservation of electricity Tuesday as a wave of triple-digit heat strained the state’s power grid.

The California Independent System Operator issued a so-called flex alert for 2 to 9 p.m., the period when air conditioners are typically at peak use and consumers should avoid running major appliances.

Energy demand for the day was forecast to exceed 48,000 megawatts, which would be the highest demand on the grid so far this year.

The Los Angeles Department of Water and Power forecast peak demand of 5,811 megawatts in the nation’s second-largest city, which would be a record for this year.

The withering blast of broiling temperatures was being spawned by an area of upper-level high pressure over Nevada.

“Just really, really hot this week, especially more than 5-10 miles inland from the beach,” the National Weather Service office for the Los Angeles region wrote.

Excessive-heat warnings and watches blanketed inland regions from the Mexico border to the Oregon state line, up and down the Sacramento and San Joaquin valleys and west toward the Pacific — but stopped short of the coastline in most areas, especially the San Francisco Bay Area, where sea breezes brought what was expected to a temporary cooling trend.

Red flag warnings for fire danger were posted along the eastern flank of the Sierra Nevada because of the threat of dry lightning, and an air quality alert was issued for San Joaquin Valley counties because of smoke from a wildfire.

Long-range forecasts did not offer much prospect of relief.

“Out of the fire and into the frying pan for the weekend,” the LA weather office said, predicting that the high pressure over Nevada will be replaced by a hot upper-level high moving into Northern California from the Pacific. “There is a chance that some areas will be hotter than they are now.”

The San Francisco weather office said that despite that region’s cooldown Tuesday and today there was increasing confidence of the new ridge of high pressure building late in the week and into the Labor Day weekend.

“Folks with any outdoor plans this upcoming weekend are urged to stay up-to-date with the latest forecast information in the coming days,” the weather service said.