California’s precipitation totals have improved significantly from the storms

California’s precipitation totals have improved significantly from the storms

The intersection of Railroad Avenue and Graton Road was flooded Sunday in the Sonoma County town of Graton. Heavy rains and strong winds led to downed trees and flooding in Northern California.

Brian Feulner/Special History

But the storms have also provided benefits, making up for rainfall deficits since the start of the current water year, which is measured from Oct. 1, 2023, to Sept. 30, 2024. That includes the Sierra Nevada snowpack.

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“We’re still chasing the average, but we’re certainly very happy that these storms helped bring us a lot closer,” said Michael Anderson, a climatologist with the California Department of Water Resources.

Coastal areas are doing better than inland areas, based on data from the National Weather Service’s Nevada River Forecast Center in California, which compares the water year so far to the average. Locations shown in teal received more rainfall than normal, while places in orange recorded less.

But it’s a big improvement from a month ago: On New Year’s Day, the entire eastern half of the state was largely below normal. Although December brought rain to California, the storms “were not penetrating inland with great force,” Anderson explained.

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December storms brought rainfall along the coast, especially in Northern California where atmospheric rivers often feed heavy rainfall. Anderson said February brought more gains as storms moved inland, bringing rain across the state, especially in the southern Sierra.

This map shows precipitation amounts so far during the water year, based on data from the National Weather Service’s Nevada River Forecast Center in California. Locations that have seen more rainfall are a darker shade of blue.

Downtown San Francisco received 16.67 inches of rain from October 1 through February 6, or 123% of normal for this time of year. About 10 inches of it came after New Year’s Day amid a series of recent storms.

Although Southern California typically faces drier conditions than the northern half of the state, a recent storm flipped the script. Checked in downtown Los Angeles 7.03 inches of rainIt is the third highest amount recorded in two days since records began at the site in 1877. This total represents nearly half of what would be expected over the course of a full year.

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Storms over the past month have also significantly boosted the Sierra’s snowpack, which supplies Californians with water as it gradually melts during the spring and summer.

“You can think of it as having an additional 15 million acre-feet of storage space if we average out,” Anderson said. By comparison, the state’s largest surface reservoir, Lake Shasta, can store up to 4.55 million acre-feet.

A cold weather system Wednesday could bring a few inches of snow to Mount Hamilton, Copernicus Peak and other Bay Area peaks above 3,000 feet.
The first week of February brought four feet of snow to North Lake Tahoe, filling the terrain at ski resorts that have had a relatively dry winter season so far.

In a snow survey conducted by the Department of Water Resources in early January, the amount of snow statewide was only 25% of normal. “Today it was 75 percent, which is absolutely fantastic,” said Andrew Schwartz, lead scientist and director of the Central Sierra Snow Laboratory at the University of California, Berkeley. “Nature has certainly given us the goods.”

It will take additional large storms to make up the deficit from earlier in the season, Schwartz said. Small to moderate storms may not fully fill the gap, but at least a near-average snowpack could be enough given the state’s filled reservoirs after a booming 2023 water year.

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“We have more resilience in terms of getting through a below-average year,” Anderson said.

Reach Jack Lee: jack.lee@sfchronicle.com

(Tags for translation) California Department of Water Resources

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