Bay Area residents could experience Tuesday similar weather conditions to those that rolled through on Monday evening, with chances for additional thunderstorms and lightning, a National Weather Service meteorologist said.
Monday's event of showers, booming thunder and lightning caused several grassland fires in the Santa Cruz Mountains and on electrical poles throughout the Peninsula. An on-duty meteorologist Monday night calculated 7,000 flashes of lightning in total, 1,200 of which were cloud-to-ground strikes. The remainder were in-cloud strikes, said Scott Rowe, a meteorologist with the National Weather Service.
The dramatic meteorological display was caused by an upper-level low pressure system, he said. It was not part of any usual seasonal weather pattern.
One lightning bolt struck an 80- to 100-foot-tall redwood tree near Maybell and Amaranta avenues at Briones Park, resident Kim Venaas said. He heard a loud crack around 9 p.m. Monday that shook his south Palo Alto home. The following morning, his wife stepped out to run errands when she saw caution tape around the tree, with the top half split into pieces.
"This is the closest we've had to a big bang," Venaas said. "I would guess the blast radius is about 70 feet."
Public Works crews were cutting the top half of the tree into smaller pieces that would be hauled out of the area on Tuesday afternoon.
In the winter, the Bay Area normally experiences stronger low-pressure systems originating in the Pacific Northwest or the western Pacific, where the the phenomenon is known as the Pineapple Express. But the low pressure that caused Monday's storm came from the California coast. These types of events are not always seen in September, making them unusual, Rowe said.
For ceraunophiles -- persons who love lightning and thunder -- there could be more to come.
"Today is the last good opportunity that will persist into the evening and potentially overnight," Rowe said on Tuesday. "There's a potential today for almost a copy-and-paste (event) for the San Francisco Bay Area and the Central Coast."
Palo Alto has a 20- to 30-percent chance of more showers and thunderstorms. The impact throughout the Bay Area Tuesday might be more scattered than Monday's display, which targeted much of the region, Rowe said.
Monday evening's event caused nearly a dozen utility-pole fires in San Mateo County and multiple grass fires in Woodside from lightning strikes, including a wildfire that was still burning on Tuesday morning near upper Bear Gulch Road and Skyline Boulevard.