Next wave in weak atmospheric river is on tap for Friday. The initial storm dumped at least a half-inch of rain in most Bay Area places
The opening wave in what meteorologists have called a weak atmospheric river system dumped about a half-inch of rain throughout the Bay Area on Wednesday and still was dropping scattered showers early Thursday, according to the National Weather Service.
It was likely to keep doing so into Thursday evening, forecasters said.
“You’re gonna see it on-and-off until it finally moves out,” NWS meteorologist Brayden Murdock said. “Then it’s gonna take a bit longer to get to the next band of rain than we first thought it would.”
The weather service now believes the second in what is expected to be a three-storm sequence is likely to hit the Bay Area early Friday, following a break of several hours. The rain is not expected to fall as hard as it did in the first storm, and the winds also were expected to be calmer, according to the weather service.
As expected, the storm Wednesday brought gusts that rose as high as 78 mph at the Black Diamond Mines in Antioch; 66 mph on Mount Diablo and 61 mph at Concord’s Buchanan Airport. The gusts were as high as 59 mph at the San Francisco Airport, in Livermore and on Mt. Umunhum in Santa Cruz County.
Those gusts accompanied showers that dropped about two-thirds of an inch of rain in south San Francisco and about one-third of an inch downtown through 7 a.m. Thursday. A half-inch of rain fell in Oakland and most parts of the East Bay. and about two-thirds of an inch fell in San Jose.
The strength of the winds came from what the weather service called a narrow cold-frontal rainband, a narrow band of storm activity that the agency on social media said is “typically short in duration but high in wind and rainfall intensity.”
A similar band that is not quite as strong is expected when the next wave of the storm hits, Murdock said. Still, it could create thunder and lightning and bring isolated showers that are powerful, according to the weather service. Such strikes were minimal and out over the ocean during the initial storm.
The third and final storm still is expected to reach the region on Sunday, dropping rain into Monday, according to the weather service. Forecasters predict a sunny day on Tuesday before more rain settles into the region on Wednesday.