Berkeley can expect 3 inches of rain in coming days

Rain is in the forecast for much of Northern California this weekend and into next week. Oakland could see up to 2.5 inches of rain, Berkeley could see around 3 inches, and Richmond could see 3.25 inches. 

The rain comes as something of a relief for the Bay Area after a historically drier water year, a hydrological timeframe starting in October instead in January. This water year, the East Bay has seen around 3 inches of precipitation less than the historical average. 

Wetter weather in Northern California comes after rain in the south brought relief and a new set of worries to Los Angeles’ fire-scorched landscape. With fires still burning nearly three weeks after the Palisades went up in flames, rain arrived last weekend after months of dry weather. The rain might be a welcome assistant in mitigating current and future fires, but it also raises concerns over mudslides and debris flows.

While an atmospheric river is on the horizon for the Bay Area, National Weather Service meteorologist Dalton Behringer said that conditions here will be relatively mild.

“We’ll have breezy south winds,” he said. “Temperatures are going to warm up because of that over the weekend — overnight temperatures, especially — and with the cloud cover, too, that’ll help keep things a little warmer. But in terms of damaging wind or anything, nothing like that for the greater Oakland area.”

‘Moisture conveyor belts’

Behringer did confirm that this storm system is fueled by an atmospheric river, a term that for Californians might call to mind the back-to-back storms between 2022 and 2023 that brought flooding to much of the state. While the term is scientific, he added, it is not one that the Bay Area’s NWS office uses lightly, lest it conjure fears of a biblical downpour. 

When California does have significant rain events, they are often due to atmospheric rivers, simply because of the state’s position on the continent. Atmospheric rivers are categorized as long, narrow atmospheric regions that carry water vapor from the subtropics. The moisture for the storm coming this Friday is sourced from this region, thus making it a traditional atmospheric river.

Despite their apocalyptic name, Behringer emphasized that atmospheric rivers are regular phenomena that only really cause issues when they linger too long. (The term has been around for decades, and it’s still the subject of scientific dispute. Some researchers prefer the more workaday name of “moisture conveyor belt.”). 

“People start freaking out and thinking that it’s going to be this big, flooding rainfall event,” he said, “when really that only happens when they stall over a certain area.”