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Record Rainfall and Flooding Devastate California: Atmospheric Rivers Continue to Soak the State

A Deluge of Rain Devastates California, Breaking Records

Relentless Rainfall Causes Flooding

A seemingly relentless barrage of atmospheric rivers keeps soaking California, dumping flooding rains and inundating streets and neighborhoods. Several feet of snow have fallen in the Sierra Nevada just this week alone, with months’ worth of rainfall coming down since the start of February at the lower elevations.

Flash flood warnings were in effect in Los Angeles Wednesday morning and San Francisco Tuesday afternoon. While rains were waning midday Wednesday, a few downpours were still pinwheeling ashore.

On Wednesday morning, all lanes of the Pacific Coast Highway were closed in Malibu because of mudslides, and a section of the 105 highway in Los Angeles was flooded. In the Bay Area, a vehicle was stranded in floodwaters in Lafayette on Tuesday afternoon, just east of San Francisco, while water was pouring out of manhole coves downtown.

Breaking a Drought

It’s been an exceptional and, in some cases, record-setting start to the year when it comes to precipitation in California. Back to back wet winters have entirely eradicated a years-long drought that once plagued the Golden State. A year ago, 84.6 percent of California was facing some level of drought; according to the U.S. Drought Monitor, that number is now zero.

How much rain has fallen?

Los Angeles downtown had already seen 12.56 inches of rain so far this month, fourth most on record and more than three times the February average of 3.48 inches.

“It is the wettest month in 26 years,” the National Weather Service said in a statement.

The city only needs just a little more than an inch to beat the February record set in 1998 — with records dating to the 1870s. Considering another atmospheric river is coming early next week, the record is in jeopardy.

The 7.03 inches that came down on Feb. 4 and 5 also represented the third-wettest two-day period on record. It falls just shy of the 7.98 inches that fell New Year’s Eve and New Year’s Day 1934.

A different rain gauge on the campus of the University of California at Los Angeles tallied 12.46 inches of rain in 24 hours during the Feb. 4 and 5 event, which has only a 0.01 percent chance of occurring in any given year.

Since Jan. 1, 14.38 inches of rain have fallen, the eighth most out of 147 years’ worth of data, and placing in the 94th percentile.

“The rainfall total for the 2023-2024 water year now stands at 17.79 inches, which is about 8 inches above the normal to date, and more than 3.5 inches above the normal for the entire year,” the Weather Service wrote.

Sacramento has seen 8.02 inches this year, a far cry from the 18.1 that had fallen by this time in 2017. This year’s total is actually only a couple inches above the average of 6.03.

Sacramento posted normal January rain, but has been running about 2 inches ahead of average for February. Its wettest so far this year was this past Sunday when 1.14 inches of rain fell.

The Bay Area is running 2.85 inches above average for the year to date. There haven’t been any true record-wet days, but rather just a string of days with moderate, steady rainfall that stacks up over time.

Year-to-date, 9.32 inches of rain have fallen, well below the record-setting 1998 when 20 inches had fallen during the same period.

The Central Sierra Snow Lab at Donner Pass, operated by the University of California at Berkeley, has recorded 211.42 inches of snow so far this season and 43.7 inches over the past week. The station is located near the Lake Tahoe ski resorts at about 7,000 feet elevation. Its snowfall so far is within a foot and a half of average for this time of year.

Despite normal snowfall, the central and southern Sierra are running 15 to 20 percent behind average for how much water is contained in the current snowpack. The reason hasn’t been a lack of precipitation, but rather the nature of atmospheric rivers; since they are connected to the tropics, they pump ashore mild air at the mid-levels of the atmosphere, which helps melt some of the extant snowpack and raise snow levels.

Weather models indicate the next atmospheric river will affect California beginning next Sunday or Monday. Thereafter, the National Weather Service’s Climate Prediction Center projects odds of above-average rainfall will last through March along the West Coast.

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