An atmospheric river bringing heavy rain to California this week helped break a 138-year-old rainfall record in San Francisco.
Atmospheric rivers are a "long, narrow region in the atmosphere—like rivers in the sky—that transport most of the water vapor outside of the tropics," according to the National Oceanic and Atmospheric Administration.
Why It Matters
On February 4, preliminary rain totals for downtown San Francisco show that the area received 2.53 inches of rain on Tuesday, breaking the previous February 4 record of 2.22 inches in 1887.
The National Weather Service (NWS) office for the Bay Area region posted on X that over 15 inches of rain has fallen in the North Bay from Friday through Tuesday, which contributed to flooding in the area.
Wet weather is expected to continue throughout this week, particularly for the San Francisco area.
What To Know
The record is only for rain that fell on February 4. The highest rain total for any day in downtown San Francisco is 5.54 inches, which was set on November 5, 1994.
San Francisco International Airport also set a daily rainfall record on Tuesday, with 1.54 inches. The previous daily record was 1.30 inches in 1991.
Some weather alerts and warnings remain in place across Northern California as the atmospheric river's impact continue.
Weather alerts still in place include a winter storm warning, winter weather advisory and flood warning.
The storms brought so much rain to Northern California that officials released water from Lake Oroville's main spillway earlier this week as a flooding mitigation effort.
More rain is expected to fall in San Francisco as the week progresses, according to a rainfall map created by NWS Bay Area meteorologists. According to the map, the Bay Area could see up to an inch of additional rain through Friday.
What People Are Saying
NWS meteorologist Roger Gass told Newsweek: "Across the North Bay, we have Santa Rosa sitting at 169 percent of normal [rainfall to date], and Napa Airport is at 122 percent of normal. The North Bay has seen the brunt of the weather systems so far this year. The further south you go, the Monterey and Salinas area is anywhere from 50 to 80 percent of average."
NWS in a forecast: "Pacific storms will continue to bring strong winds, heavy rain with a risk for flooding to northern and central California, and heavy mountain snow in the Sierras, southern Cascades, and northern Rockies through Friday."
What Happens Next
According to the NWS Climate Prediction Center, much of the Golden State is expected to experience above-normal precipitation for the next eight to 14 days, as below-normal temperatures are predicted for the same period.
Gass said another system could hit mid-week next week, but it's too far out to have many details.
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