State's estimated rainfall in last 10 days: 10 trillion gallons

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Ana Fuentes makes her way through the rain and walks past the mural by Robert Vargas and Michael Blaze entitled, “Our Lady of DTLA,” that graces the SB Tower building at 6ht and Spring Streets People in downtown Los Angeles. (Genaro Molina / Los Angeles Times)

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A lone shopper makes her way across the rain-slicked path near a Christmas display at the Santa Monica Place shopping center in Santa Monica on Tuesday. (Genaro Molina / Los Angeles Times)

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Los Angeles City Hall is reflected in drizzle collected on a walkway at Grand Park in downtown Los Angeles on Tuesday morning. (Irfan Khan / Los Angeles Times)

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Santa Monica College students Nicole Nicks, left, and Krysta Zeldin, stay dry under the big umbrellas they brought Tuesday to Tongva Park in Santa Monica to celebrate the completion of finals. (Genaro Molina / Los Angeles Times)

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Shoppers walk past a winter display on Santa Monica Boulevard in Santa Monica while bracing against the cold and rain Tuesday. (Genaro Molina / Los Angeles Times)

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A bicyclist makes her way along Main Street during Tuesday morning rain in Venice. (Genaro Molina / Los Angeles Times)

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An L.A. Fire Department swift-water rescue team pulls a woman from the swollen L.A. River Friday near Atwater Village. (Marcus Yam / Los Angeles Times)

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Storm clouds drift over downtown Los Angeles as the sun sets. The brunt of a Pacific storm struck Southern California, dropping about 1.5 inches of rainfall on the Civic Center. (Luis Sinco / Los Angeles Times)

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Global Eagle Entertainment, which provides in-flight entertainment for Southwest Airlines and others, has been hit by executive resignations and financial reporting problems. (Brian van der Brug / Los Angeles Times)

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Salvador Medina clears mud from a garage in Camarillo Springs. (Al Seib / Los Angeles Times)

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A car is encased in a mudslide on Pacific Coast Highway near Sycamore Canyon. (Anne Cusack / Los Angeles Times)

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Workers remove mud and debris from multiple mudslides on PCH in Malibu. (Anne Cusack / Los Angeles Times)

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Workers head toward a car stuck in a mudslide on PCH near Sycamore Canyon. (Anne Cusack / Los Angeles Times)

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Homes on San Como Lane are buried to their roof by the debris flow in Camarillo Springs. (Al Seib / Los Angeles Times)

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Barbara Williams, left, president of the homeowners association, and resident Barry Gilbert view the debris flow in Camarillo Springs. (Al Seib / Los Angeles Times)

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Media look at the debris flow that filled homes and backyards along San Como Lane in Camarillo Springs. (Al Seib / Los Angeles Times)

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Erwin Fodram, a 20-year resident, looks at homes on Gitana Avenue buried by the debris flow in Camarillo Springs. (Al Seib / Los Angeles Times)

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Los Angeles Fire Department swift water rescue members assist a woman after pulling her from the gushing waters of the Los Angeles River. (Marcus Yam / Los Angeles Times)

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The Los Angeles downtown skyline appears as seen from Azusa under scudding clouds. (Irfan Khan / Los Angeles Times)

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An L.A. Fire Department swift water rescue worker makes his way across the storm-swollen Los Angeles River to rescue a woman stranded on an island. (Marcus Yam / Los Angeles Times)

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Fire Department swift water rescue members make their way across the storm-swollen Los Angeles River after rescuing a woman. (Marcus Yam / Los Angeles Times)

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L.A. Fire Department swift water rescue members saved a woman from an island in the middle of the storm-swollen Los Angeles River. (Marcus Yam / Los Angeles Times)

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A park rangers keep watch for people in the storm-swollen Los Angeles River during a search and rescue mission. (Marcus Yam / Los Angeles Times)

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An L.A. Fire Department rescue helicopter flies low over the storm-swollen Los Angeles River in search of people in the water. (Marcus Yam / Los Angeles Times)

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A LA Fire Dept. rescue helicopter flies low over the swollen Los Angeles River in search for possible people trapped in Atwater Village. (Marcus Yam / Los Angeles Times)

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An L.A. Fire Department urban search and rescue team member floats down the L.A. River after his line snapped as he tried to swim to an island in the Atwater Village area during rescue operations Friday. Firefighters downriver pulled him to safety. (Robert St. John / Los Angeles Times)

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Susan McCown checks out the damage to her niece’s apartment after a second-story balcony on a mixed-use building in Long Beach partially collapsed Friday morning. (Allen J. Schaben / Los Angeles Times)

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Ventura County Sheriff’s deputy Guy Stewart surveys the cascade of mud and rock that covered Gitana Ave in Camarillo Springs Friday morning. (Al Seib / Los Angeles Times)

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A fallen tree blocks Vermont avenue in the Los Feliz neighborhood Friday morning. (Marcus Yam / Los Angeles Times)

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Workers clear out a large tree that fell and blocked Vermont Avenue in the Los Feliz neighborhood of Los Angeles. (Marcus Yam / Los Angeles Times)

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Ventura County sheriff’s deputies climb the cascade of mud and rock that filled the backyards of homes along San Como Lane in Camarillo Springs on Friday morning. (Al Seib / Los Angeles Times)

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Roof-high mud and rock fill the backyards of homes along San Como Lane in Camarillo Springs Friday morning. (Al Seib / Los Angeles Times)

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Homes along San Como Lane in Camarillo Springs are damaged by heavy mudflow from the latest storm Friday morning. (Al Seib / Los Angeles Times)

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Amanda Heinlein stands by regular size basketball hoop in her backyard at Ridge View Drive that is buried in mud caused by early morning rain in Azusa. (Irfan Khan / Los Angeles Times)

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Edward Heinlein, who has protected his home with sand bags and plywood fencing, is still worried about the mud and debris getting into his hom on Ridge View Drive in Azusa. (Irfan Khan / Los Angeles Times)

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Glendora police close off westbound Sierra Madre Avenue at Barranca Avenue due to the danger of mudslides Friday morning. (Irfan Khan / Los Angeles Times)

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Commuters stand on the platform as they wait for a northbound Metrolink train in the rain at the Irvine station Friday morning. (Marc Martin / Los Angeles Times)

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A commuter make his way across a pedestrian walkway at the Irvine Metrolink station as rain continues to fall in the Southland Friday morning. (Marc Martin / Los Angeles Times)

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A major storm approaches the Los Angeles skyline, bringing with it heavy rainfall and the possibility of flash floods and debris flows. (Allen J. Schaben / Los Angeles Times)

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A stand-up paddle boarder makes his way into the waves along the beach in Ventura County as a storm from Northern California enters the area. (Rick Loomis / Los Angeles Times)

By Matt Hamilton, Matt Stevens

Dec. 14, 2014 5:07 PM PT

How much rainfall has hit California in the last 10 days?

It’s hard to calculate. But one weather expert, Ryan Maue, offers this estimate: 10 trillion gallons.

That’s enough to fill 15.1 million Olympic-size swimming pools or power Niagara Falls for 154 days.

Using data from the National Weather Service, Maue — a Florida-based meteorologist for WeatherBell Analytics — calculated that an average of 3.5 inches of water fell across the Golden State.

In places such as the Sierra Nevada, where several inches of snow fell, Maue’s model liquefied the powder: 1 inch of water for every 10 inches of snow.

Since 1 inch of rain in a square mile works out to 17,378,742 gallons, and California has 163,696 square miles — voila, 10 trillion.

So how accurate is this estimate?

“It’s an accurate number, but it’s based on how good the precipitation data is,” Maue cautioned. “There’s no way to know exactly.”

Craig Shoemaker, a meteorologist with the National Weather Service’s Sacramento station, agreed that it’s a “kind of a neat number” but, alas, imperfect.

“We don’t take instantaneous observations at every point in the state,” Shoemaker said. “There’s going to be some level of inaccuracy.”

Maue’s data were based on totals from 4 a.m. Friday — meaning that daylong rains across Southern California on Friday could push the total higher.

And new storms are expected this week as well.

Is it true last week’s storms caused a tornado?

Yes, though the National Weather Service is calling it a “small tornado.”

The tornado hopscotched over a 10-block span of South Los Angeles on Friday morning, ripping off a roof and damaging at least five homes. There were also reports of water spouts off the coast.

Did the storms help California’s ravaged snowpack?

Yes.

The storms are expected to add several feet of snow in parts of the Sierra. The state’s snowpack is important because when it melts during the summer months, the water can replenish reservoirs.

Snowpack was essentially depleted by late spring of this year, according to state data.

The recent rains have helped boost the snowpack. As of Friday, it had climbed to 40%.

Water officials have maintained that significant storms such as last week’s drenching and this week’s downpour would need to continue throughout the winter to have a significant effect on the drought.

matt.hamilton@latimes.com

matt.stevens@latimes.com

State’s estimated rainfall in last 10 days: 10 trillion gallons

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