Southland Could Get a Lightning Show Today

Chances for a spectacular lightning show over Southern California mountains and deserts are one in three today, but the possibility of thunderstorms will decrease as the weekend progresses, forecasters said.

For the second consecutive day, high temperatures and humidity led to record usage of electrical power by Southern California Edison Co. customers. The utility provided 15,487 megawatts of power Thursday, breaking a record of 15,277 set the day before.

High temperatures in Orange County ranged from 91 in Santa Ana and San Clemente to 75 in Newport Beach. San Juan Capistrano and El Toro reported highs of 89; Laguna Beach reached 82.

Thursday’s air was more than hot and wet: It was also dirty. The South Coast Air Quality Management District called first-stage smog alerts--meaning that the air is unhealthful for everyone--in Glendora and the eastern San Gabriel Valley. First-stage alerts were also called in the Pomona and Walnut valleys and the Riverside area.

Cooling Trend Seen

High temperatures today will cool by a few degrees, ranging from 89 in Santa Ana to 74 in Newport Beach, forecasters said. Desert areas will see weekend highs between 100 and 113.

Humidity during early morning hours will be as high as 85%, more than 30% above average for July, said Dave Beusterein, a meteorologist with WeatherData, Inc., which provides forecasts for The Times.

The sopping-wet air results from an upper level high pressure system centered over Northern California that is drawing moisture west and northwest from Mexico and Arizona, Beusterein said.

That moisture, combined with the intense heating that creates low pressure at the surface during the afternoon, produces the lightning and thunderstorms that have plagued firefighters, who were kept hopping from brush fire to brush fire this week.

A fast-moving blaze in the Lytle Creek Canyon area of San Bernardino County threatened several isolated homes Thursday afternoon, but there were no immediate reports of structural damage or injuries. Thunderstorms were reported in the region, but the cause of the fire was under investigation.

Storm Concentrations

“The heaviest concentration of storms (today) will be in the San Gabriel and San Bernardino mountains, as well as Palm Springs and others areas of the Western low deserts,” Beusterein said.

The chance of thunderstorms will be no better than 20% on Saturday as the high pressure system breaks down and drier air begins flowing through the upper atmosphere, Beusterein said.