The National Weather Service shared a satellite loop Tuesday afternoon showing thunderstorms 200 miles offshore from the San Francisco Bay Area.

Storm activity is pushing north and is not expected to affect the region on Tuesday, the weather service said, but there is little risk of thunderstorms in the Bay Area on Thursday.

“It’s part of the same large-scale moisture system that comes in from the south and is directed north because of that high pressure system parked in Nevada-Utah,” said Jeff Lorber, a meteorologist with the National Weather Service’s Bay Area office. “There’s also a small trough off the coast of Northern California. That moisture is channeled south-north between these two systems.”

OK Weather Watchers, does anyone notice the thunderstorms ~ 200 miles offshore? Here is a satellite loop pointing the thunderstorms north. No effects on the country are currently expected. #cawx pic.twitter.com/EfpBNedAVs

– NWS Bay Area (@NWSBayArea) September 7, 2021

The highest likelihood of storm activity in the Bay Area on Thursday is in the far North Bay in Napa and Sonoma counties.

Lorber said the odds were 15 to 20% on Tuesday night.

“The biggest opportunity right now is over North Bay,” he said. “It’s still far out. We’ll have a better idea tomorrow. As of now, the threat elsewhere[outsidetheNorthBay”isprettylimited”[outsidetheNorthBay”[außerhalbderNordbucht”ziemlichbegrenzt”[outsidetheNorthBay”

Any lightning that strikes is likely to be dry, and rain that falls could evaporate before it hits the ground.

While the likelihood of being struck by lightning is small, the risk is high as a strike could spark wildfire. California has experienced two consecutive dry winters and the vegetation is parched and flammable.

The high pressure, which has driven the temperatures up in the last few days, will cause another hot day on Wednesday, said the weather service. Temperatures on the coast will be in the 60s and 70s, while the higher inland temperatures will rise to 105 in the 90s.

Temperatures are expected to drop on Thursday when the ocean layer returns and the upper level moisture reaches the region.

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San Francisco saw its first measurable rainfall since 2019, when thunderstorms swept across parts of the Bay Area on late Thursday and early Friday mornings and firefighters scrambled to contain new fires.

According to the National Weather Service, the official display in downtown San Francisco picked up 0.01 inches of rain as of 5 a.m. on Friday.

“It has been a long time since it rained specifically on September 10 at the official display in the city center,” the service tweeted. “The last time was 1978 with 0.08 (inches). For each day in September, the last time there was measurable rain in SF was on the 27th in 2019, 0.03 (inches).

Thunderstorms hit San Francisco on Friday before sunrise, after moving to the Bay Area on Thursday afternoon and evening. They were expected to calm down after sunrise.

Parts of the Bay Area, particularly the North Bay and East Bay, saw the occasional lightning bolt and light rain while the firefighters watched closely.

The North Bay rain readings on late Thursday ranged from 0.01 to 0.11 inches.

It was the first rain in weeks in some areas, but weather forecasters warned that dry lightning could pose a serious threat in exceptionally dry conditions.

Much of Northern California, as well as the mountains and valleys of North Bay, the hills and valleys of East Bay, and the Diablo Range had a red flag indicating that hot temperatures and low humidity combined with the risk of dry lightning and strong winds , Create conditions for forest fires to ignite and grow rapidly.

Lightning strikes and showers were reported in and around Marin, Sonoma, and Napa counties at 9:00 p.m. Thursday. Cloud-to-ground lightning strikes have been confirmed in Sonoma and Santa Clara counties, according to the National Weather Service.

The agency reported cloud-to-cloud lightning strikes over Colusa, San Joaquin and Madera counties, as well as increased storm activity west of San Francisco.

In Oakland, near Lake Merritt, the light rain was enough to interrupt a street musician’s performance on late Thursday and distract his audience.

Andy Picon is a contributor to the San Francisco Chronicle. Email: andy.picon@hearst.com Twitter: @andpicon

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