Bay Area could see over 5 inches of rain next week

San Francisco Bay Area meteorologists are honing the forecast for a prolonged wet period expected to start Sunday and continue into at least Thursday, and maybe Friday and Saturday, of next week. At least two storms are predicted to sweep through the region. 

While the exact timing and rainfall totals with these systems remain uncertain, the National Weather Service said the most recent forecast suggests the majority of the area could see weekly totals of anywhere from 1 to 5 inches of rain Sunday through Thursday. Some locations along the coast could see upward of 4 to 6 inches of rain. 

“With rain spread out over multiple days, nuisance roadway flooding remains the most likely impact,” the weather service said in an emailed statement.

The heaviest rain in the upcoming forecast is expected Sunday night into Monday as a system moves across the Pacific Ocean and pushes into California. Isolated thunderstorms and gusty southerly winds are possible with this system. 

“We’ll have some prefrontal stuff push through and the main rain band is going to be Sunday into Monday, and that’s going to be our highest chance for moderate to heavy rainfall,” said Brayden Murdock, a forecaster with the weather service’s Bay Area office.

Murdock said there’s a slight potential for the storm to stall a little, with the onset of heavy rain pushing from Sunday night to Monday.

This low-pressure system will be ushered into California by the jet stream — those high-altitude winds that carry storms. The jet stream has been focused over the Pacific Northwest in recent weeks, delivering a parade of storms to Oregon and Washington, but on Sunday, its position is expected to shift into California. This will open the storm door in the Golden State.

“As this storm comes through on Sunday, the jet stream is just a little bit ahead of it and it will actually pull this low pressure into California,” Murdock said.

After Sunday, the jet stream is expected to remain extended into California. “That’s why we get the opportunity to see multiple low-pressure systems next week and that’s why it’s going to be a rainy week,” he said.

A second system is expected to reach California on Tuesday and bring a chance for rain into Wednesday, Thursday, Friday and maybe Saturday.

“This system will be more showery, so you don’t get that whole rain band bringing heavy rain,” Murdock said. “There will be scattered showers passing through.”

The forecast for this second system could change in coming days.