Unexpected Guests: Lightning, Hail

A brief but ferocious thunderstorm swept across Southern California on Thursday, dropping hail, fraying nerves and sending three high school students to a hospital.

“It’s not the showers that were surprising,” said Amy Talmage, a meteorologist for WeatherData Inc., which does forecasts for The Times. “It was the hail and lightning--the intensity of the storm.”

No serious weather-related incidents were reported in Orange County. But at Oceanside High School in San Diego County, three students were hospitalized after lightning struck an outdoor basketball court late in the afternoon. Though no one was actually struck by the bolt, officials said, the three were shaken up. All were treated and released.

“I would call this unseasonable for Southern California,” Talmage said. In fact, she said, “I think something of this type is unusual no matter where it happens.”

The storm had its origin in an upper-level pool of cold air that spent much of the week hovering harmlessly off the coast, she said. On Thursday it meandered farther south, where it hit a warm, subtropical jet stream that had been blown to the north.

The result was a sudden, tropical-like storm that hit the San Diego area about 4:30 p.m. and headed north, causing thunder and lightning on the way, dropping 0.1 inch of rain across wide swaths of Southern California and pelting some areas with small hailstones. The rainfall in the foothills, Talmage said, was two to three times as heavy.

Temperatures remained warm, from 67 at the Santa Monica Pier to 93 in Pasadena.

Officials at the Wild Animal Park in San Diego County’s San Pasqual Valley were alarmed enough by the lightning to herd visitors into protected areas. No injuries to humans or beasts were reported.

The good news, Talmage said, is that residents hoping to spend the weekend outdoors need not change their plans. The rain is expected to subside by early this morning, she said, and the day should be mostly sunny with a few low clouds along the coast. High temperatures across the region are expected to range from the mid-70s to low 90s.

Friday night likely will bring patchy low clouds and fog, yielding to mostly sunny and slightly cooler weather Saturday. Forecasters expect Sunday to be much the same, Talmage said.

“I would consider it a very pleasant weekend to do anything outdoors,” she said. “It may not be kite-flying weather, but anything else outdoors is good.”

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Times staff writer Tony Perry contributed to this report.