The storm hitting California is not an atmospheric river. What is?

Early weather forecasts suggest California could see a super-soaked atmospheric river this week.

Last week’s forecast didn’t hold up. Meteorologists no longer use that label to describe the system that brings a chance of rain to the Golden State Tuesday through Sunday.

“It’s not an atmospheric river,” said Brian Garcia, a meteorologist with the National Weather Service. “This is a classic Gulf of Alaska low.”

That means the storm will fall from the Gulf of Alaska instead of pulling moisture from the subtropics, the South Pacific that includes the Hawaiian Islands.

“This low pressure area and its associated moisture and energy is coming from a large high pressure area that is over the central Pacific Ocean,” Garcia said. “Eventually, this system will get far enough south that it can touch some subtropical moisture, and even then I would never classify it as an atmospheric river.”

Along with the change in storm pattern came a drop in total precipitation, especially in the northwest corner of Northern California. Initial forecasts say the Eureka area could see 5 to 6 inches of rain over several days. “We’re now looking at amounts that will be 1 to 2 inches, with isolated heavier amounts,” said Rich Bann, a forecaster with the weather service’s Climate Prediction Center.

Far Northern California often gets more rain than the Bay Area when storms sweep the coast. Ban said that with this system, the Bay Area could see rainfall amounts that are similar to those recorded up north.

Rainfall forecasts have also decreased slightly in other parts of California. Last week, forecasters predicted that up to 2 to 3 inches of rain could fall in downtown San Francisco. The latest forecast is that it could see 1 to 1.5 inches. Total forecasts for San Luis Obispo and Los Angeles counties have dropped from 2 to 4 inches of rain to about 2 inches or less. Of course, the forecast continues to evolve and more or less rain may fall.

“The heaviest rainfall appears to be confined to the coast and mostly offshore,” Ban said.

Here are some more specific forecasted rainfall totals for locations around California:

Northern Californiafrom Tuesday to Saturday
Eureka: 0.5 to 1 inch
Redness: 0.25 to 0.5
Quincy: 0.1 to 0.25
Chico: 0.5 to 1 inch
Sacramento: 0.5 to 1 inch
Yosemite Valley: 1 to 1.5 inches
Fort Bragg: 1 to 1.5 inches
Santa Rosa: 1 to 1.5 inches
San Francisco 1 to 1.5 inches
San Jose: 0.5 to 1 inch

Atmospheric rivers are known to carry huge amounts of moisture from the subtropics and release heavy rain when they hit land. Ban said last week some long-range weather models showed that this storm was “picking up a plume of moisture from the Pacific Ocean and transporting it to the West Coast in an atmospheric river fashion.”

This forecast was from 5-6 days ago, and the weather developed differently. “We still have an area of ​​low pressure off the west coast of California. It is further west than when we spoke last week,” Ban said. “It’s not going to have the same plume of deep moisture that it may have had a few days ago.”

As of Tuesday morning, the storm was several hundred miles off the coast of Mendocino. The system is expected to “wobble off the coast of California” for several days, sending waves of rain toward the state before moving over land over the weekend, said Roger Gass, a weather service forecaster.

Gass said the Bay Area and Monterey regions are expected to receive three different main waves of rain with this storm. The first arrived Tuesday morning and moved quickly across the region, with conditions mostly dry this afternoon and evening. A second is forecast to bring more rain on Wednesday, the day the Bay Area could see the heaviest rain associated with this system. A third is likely to sweep into the region Friday through Saturday. With this latest wave of rain, the Monterey area will likely receive more rain than the Bay Area, according to Gass.

As the storm moves inland over the weekend, it will move across Central and Southern California, Gass said.