As expected, lightning lit up the Bay Area on Thursday, and small amount of rain fell, but forecasters with the National Weather Service said danger still loomed Friday morning as remnants of a southwestern monsoon system moved toward Sacramento and Nevada.
A red-flag warning remained in effect until 11 a.m., and forecasters said more lightning may occur before then but that much of the lightning over the Bay Area had ceased. The weather service said it confirmed about 110 cloud-to-ground lightning strikes in the Bay Area, and meteorologist Brayden Murdock said most of them were in the North Bay.
About 1,100 lightning strikes had been recorded in the whole state since Thursday evening, the weather service said.
Lots of chatter about lightning⚡ this morning. Lets take a look at the last 24 hours and how the lightning moved through the state. Here’s a loop showing GLM data from GOES West 🛰 view the imagery for yourself https://t.co/eHseCz04FX #cawx #cafire pic.twitter.com/7IbX8a1lbR
— NWS Bay Area (@NWSBayArea) September 10, 2021
The storm did not appear immediately to leave any major damage locally, and local fire crews were spared any major disasters.
Oakland firefighters responded to a vegetation fire in the Oakland hills off Grizzly Park near the Sibley Volcanic Regional Preserve off Skyline Boulevard around 8:30 p.m. and had it under control in an hour, keeping it at 100 feet-by-100 feet, according to Oakland Fire spokesman Michael Hunt.
Fire officials also said crews in the eastern part of Contra Costa County responded to a fire in the 18,000 block of Marsh Creek Road around 10 p.m. that turned out to be a pile of leaves, and a small brush fire in Antioch. Officials said there was no immediate reason to believe that the Antioch fire was caused by lightning but had no cause immediately for the other one.
Lightning caused bigger issues in the fight against the Caldor Fire, as officials from the California Department of Forestry and Fire Protection said firefighters were diverted to fight multiple lightning-strike fires throughout El Dorado County. The biggest of those fires was on Kanaka Valley Road in Rescue, according to the agency.
Firefighters were diverted from the Caldor Fire to fight multiple lightning fires late last night throughout El Dorado County. Lightning from heavy storm cells passing through the northwestern part of El Dorado County started the largest on Kanaka Valley Road in Rescue. pic.twitter.com/wo05Iz7JDz
— CAL FIRE AEU (@CALFIREAEU) September 10, 2021
Rain fell heavily in spots and hardly at all elsewhere. Parts of Richmond and other areas of western Contra Costa County measured nine-hundredths of an inch of rain, as did parts of Martinez and areas near the Cummings Skyway. In San Francisco, the .01 inch that fell was the first time in two years the city has received any measurable rain in September.
As the storm migrates east, forecasters said a cool front will follow it into the Bay Area and that expected temperatures in the mid-80s will feel as if if they’re in the mid-80s. The hottest spot in the region on Thursday was in Brentwood (101 degrees). Only Walnut Creek, Concord, Pittsburg and Antioch reached the 90s, though forecasters said the humidity that arrived with the storm made it feel as if it was that hot in most places.
The relief will be brief, as temperatures in the interior East Bay are expected to be back in the mid-90s by Sunday, and areas of the Santa Clara Valley are likely to be back in the 90s.