California Atmospheric River Triggered Flooding, Debris Flows and Feet of Sierra Snow

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This storm guided a long plume of Pacific moisture called an atmospheric river into California. You can see this ribbon of moisture in this animation from Scripps Institution of Oceanography at the University of California-San Diego and also in the satellite loop below.

This storm entered California late on Jan. 26, and lingered in California through Jan. 29.

As the initial cold front swept into the state, high winds knocked out power to more than 400,000 homes and businesses in Northern California at one point, according to poweroutage.us.

Wind gusts over 60 mph were clocked in the Sacramento and a number of locations in Northern and Southern California. Gusts at Alpine Meadows near Lake Tahoe were clocked at over 120 mph.

This atmospheric river stalled for a time over central California, on Jan. 27 and 28, wringing out prolific rain over areas recently charred by wildfires, triggering destructive flows of mud, rocks and other debris.

One such debris flow damaged two dozen homes in Salinas, California.

A section of Highway 1 - the Pacific Coast Highway - near Big Sur washed out due to heavy rain.

In Southern California, a mudslide blocked the garage of a Silverado Canyon home in the Santa Ana Mountains, while another mudslide trapped a car in Azusa.

There were almost two dozen reports of debris flows, and over 60 reports of flash flooding in California during the storm, from just north of the Bay Area to the San Joaquin Valley and Sierra foothills, central coast and Coastal Range, and also in parts of the L.A. Basin and San Diego County. These reports are shown as blue dots in the map below.

Rainfall totals topped 15 inches in a few locations in Monterey and San Luis Obispo counties. Some areas in the Santa Cruz Mountains picked up more than 6 inches of rain.

As colder air aloft moved into Southern California, thunderstorms brought a light accumulation of hail on Jan. 29, including Manhattan Beach.

Sierra Slammed

Mammoth Mountain in the southern Sierra reported 94 inches of new snow in 72 hours at the resort's main lodge, with 107 inches of storm-total snowfall at the summit.

Even areas on the leeward side of the Sierra were clobbered with heavy snow.

The town of Lee Vining, California, in Mono County, picked up 33 inches of snow in 24 hours.

The National Weather Service office just north of downtown Reno, Nevada, measured almost 21 inches of snow as of Jan. 29. Their average yearly snowfall is 21.8 inches.

Although this snowpack is beneficial for California's water supply and ski areas, it was crippling for travel.

Interstate 80 through Donner Pass - the main route between the Bay Area and Sacramento into Nevada - was shut down, at times.

Various other roads were closed for a time, including U.S. 395, Interstate 5 in far Northern California, and the Grapevine through L.A. County.

Blizzard conditions were reported on Interstate 5 in far Northern California near the town of Weed, where at least 20 inches of snow had fallen, stranding vehicles.

Parts of the Southern California high country also picked up a foot of snow, including Lockwood Valley in Ventura County and Palomar Mountain in San Diego County.

This wasn't just a California story.

Parts of Idaho picked up over 2 feet of snow. The town of McCall, about 90 miles north of Boise, had their heaviest two-day snowstorm since 1971.

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