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32 trillion gallons of water in 3 weeks: California storms by the numbers

The onslaught of storms produced record rains, more than 20 feet of snow, hurricane-force winds, more than 2 million power outages and at least 20 deaths

Area residents stand in flooded streets in the Felton Grove neighborhood of Santa Cruz after a powerful storm on California's Central Coast on Jan. 9. (Melina Mara/The Washington Post)

From late December to the end of this week, a parade of storms slammed California, unleashing tremendous amounts of rain and snow along with bouts of damaging winds and punishing surf.

Even as the storms made a big dent in the state’s multiyear drought, they were harmful and costly. Coastal erosion, toppled trees, flooding, mudslides and rockslides left behind destruction. And the storms killed more people than any California wildfire since 2018.

Here are some of the key numbers that help put the storms into perspective:

9 atmospheric rivers — Nine separate atmospheric rivers — or narrow plumes of deep moisture generated by ocean storms — walloped California from Dec. 27 to Jan. 16, according to atmospheric scientist Marty Ralph and his colleagues at the Center for Western Weather and Water Extremes in La Jolla.

Ralph said the strongest of the atmospheric rivers hit Northern California and Oregon on Dec. 27. It was rated Level 4 of 5, only missing Level 5 because of its quick movement. Nonetheless, the intensity of that particular river was exceptional, Ralph said in an email.

11.47 inches of rain — The statewide average rainfall for California was just shy of a foot, according to the National Weather Service Weather Prediction Center. Many locations received almost their entire annual rainfall over the approximate three-week period.

Several locations in the San Francisco Bay Area saw near record amounts.

Here are some notable totals:

  • Honeydew: 47.72 inches
  • Santa Cruz: 39.55 inches
  • Blue Canyon Airport: 34.28 inches
  • Shasta Dam: 26 inches
  • San Francisco downtown: 17.74 inches
  • Death Valley: 0.29 inches.

Locations that saw their wettest 23-day stretch on record include:

  • Mount Hamilton (east of San Jose): 20.05 inches
  • Oakland International Airport: 16.48 inches
  • Redwood City: 16.00 inches
  • San Francisco International Airport: 15.29 inches
  • South Lake Tahoe: 14.46 inches
  • Merced: 10.26 inches

An analysis of rainfall data suggests maximum amounts reached around 65 inches in mountainous areas of coastal Northern California. It also showed that more than 20.2 percent of the state saw totals of 20 inches or more, focused on the Sierra Nevada and coastal ranges.

32 trillion gallons of water — The nearly one foot of rain averaged over the entire state equates to about 32 trillion-plus gallons of water. California was not the only state to be doused by the series of atmospheric rivers. The moisture pushed into much of the Intermountain West, bringing record-challenging amounts of precipitation to numerous locations.

60-foot water rise — The water level has risen 60 feet in the past month at Shasta Dam — vastly improving Lake Shasta’s water supply.

Lake Shasta’s water level is 85 percent of its historical average for the date, and at 53 percent of its capacity. Reservoirs are fuller than they’ve been in at least a few years, but more precipitation is still needed.

20 feet of snow — Mammoth Mountain ski resort in the central Sierra Nevada reported 243 inches since the days after Christmas, including an additional three inches Thursday morning. It received at least 30 inches of snow on three days during the stretch. Palisades Tahoe — about 150 miles to the north — reported 203 inches, including nine new inches on Thursday. About 12 miles to the northwest, UC Berkeley Central Sierra Snow Lab registered 192 inches of snow during the span.

An analysis of snowfall data suggests totals of 300 to 400 inches fell in the snowiest locations between the wilderness east of Yosemite and Mount Whitney, the highest peak in the Lower 48.

250 percent more snow water than average — As the atmospheric rivers wound down, snow water equivalents — or amounts of water contained within the snowpack — were as high as 288 percent of the norm in the southern Sierra, 248 percent in the central Sierra and 209 percent in the northern Sierra. The statewide average peaked at around 250 percent of normal.

On Thursday, the entire Sierra Nevada region’s snow water equivalent was around 126 percent of the April 1 norm or above the average amount received over an entire season.

160 mph wind gust — A wind gust reached a roaring 160 mph near the summit (at around 8,700 feet) of Palisades Tahoe on Dec. 30. At least 10 locations reported gusts of 100 mph-plus over the stretch, mainly in the Sierra Nevada but a few such gusts were also noted in the mountains of Southern California east of Los Angeles.

On Jan. 8, high winds toppled thousands of trees around Sacramento because of the combination of high winds and saturated soils from heavy rain.

20 deaths — The onslaught of storms has killed at least 20 people. A 5-year-old boy separated from his mother in floodwaters remains missing.

More than 1 billion dollars in damage — The cost of the storms is expected to top 1 billion dollars, making it the first such disaster of this magnitude of 2023. Six counties — Santa Cruz, Merced, Sacramento, Monterey, San Luis Obispo and Santa Barbara — were declared major disasters by the Biden administration. Few counties were untouched.

2.1 million without power — At least 2.1 million people lost power, according to Pacific Gas & Electric, which covers the core of the state from Eureka to Santa Barbara and inland. The utility called it “the single largest winter storm response in PG&E’s history.”

0 percent of state left in extreme or exceptional drought — Three months ago, the federal drought monitor classified 41 percent of California in its top two tiers of drought: extreme and exceptional. That number is now zero. However, more than 90 percent of the state is still classified under more mild drought levels.

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