An overturned vehicle is seen on Highway 395 near Mammoth Lakes, Calif. on Jan. 9 as a series of strong storms moved through. (David Mcnew/AFP/Getty Images)

— Hurricane-force winds in the mountaintops and torrential rainfall in the valleys caused havoc in Northern California on Monday, flooding roadways and stranding drivers on major highways after mudslides.

The extreme weather pummeling the Sierra Nevada is the result of a meteorological phenomenon known as the “Pineapple Express,” which ushers an atmospheric river of moisture-rich warm air north from the tropical waters of Hawaii. The powerful storm has blasted Lake Tahoe and the Yosemite Valley with several feet of snow and drenching downpours, with more than 12 inches of precipitation in some locations — and more to come this week.

All of the ski resorts surrounding Lake Tahoe were shut down amid the winds and snow, and the San Francisco area received more rain during the first eight days of 2017 than it did during all of 2013.

At the Squaw Valley ski resort, a historic 173-mph wind gust was recorded on its 8,700-foot peak, equivalent to a Category 5 hurricane powerful enough to rip buildings off their foundations. National Weather Service forecasters in Reno, Nev., indicated that the wind was probably a record. At Squaw Valley, sustained winds of 100 mph howled at the peak for more than an hour, speeds that typically peel shingles off rooftops.

(Monica Akhtar/The Washington Post)

“It was extremely windy here,” said Sam Kieckhefer, a spokesman for Squaw Valley and a longtime Tahoe skier. “We have no reason to doubt the accuracy of that measurement.”

The storm also toppled a giant sequoia known as the “Pioneer Cabin Tree,” a well-known tourist attraction with a tunnel wide enough for a car to pass through carved into its base. The tree was in Calaveras Big Trees State Park, southwest of Lake Tahoe, where some trees are estimated to be 1,000 years old. It was 150 feet tall and measured about 33 feet in diameter, and the storm felled the tree with ease, splintering the trunk into pieces.

Across California, roads were closed because of high waters and dangerous conditions. A massive mudslide shuttered Interstate 80 near Donner Summit, leading some drivers to seek alternate routes; some followed their phone’s map directions onto a sketchy switchback two-lane road that was covered in snow, stranding them there.

“Do not blindly follow GPS!” tweeted the Washoe County Sheriff’s Office.

The roadway hazards also may have contributed to a traffic fatality near the Oakland Airport, where a taxicab was found submerged in an estuary. The driver died.

Officials have logged more than 100 reports of flooding or landslides in California during the past 48 hours, according to reports. The Sierra Avalanche Center also said there was considerable risk for slides in the high Sierra.

A person shovels snow from a roof in Mammoth Lakes, Calif., on Jan. 9. More storms are forecast for this week. (David Mcnew/AFP/Getty Images)

“Dangerous avalanche conditions still exist, and large, deep, destructive human-triggered avalanches remain likely due to deep slabs and wind slabs,” the center wrote in an advisory. “This danger rating is when the most avalanche fatalities occur.”

In the Tahoe area, flooding continued to fluster residents. Tenaya and Nick Durfy had spent the weekend placing sandbags around their home to little avail. By Sunday their house was inundated.

“All of a sudden, water just started coming out of everywhere,” said Tenaya Durfy, who is seven months pregnant. “Water flooded through the entire house. I couldn’t keep up with it, so I focused on getting our stuff off the ground.”

Seeking to help, neighbors came by the Durfy home with shovels to dig a trench, hoping to redirect the floodwaters, and also supplied the couple with sump pumps, a generator and beer, she said.

“Me and my husband were overwhelmed with how generous and helpful everyone was,” Durfy said. “People just showed up. Even people I didn’t know. If they didn’t come, I don’t know what would’ve happened. It was amazing.”

The Truckee River in Reno crested at 12.3 feet — more than three feet over flood stage — early Monday. It was the highest crest since the historic flood of 2005, when the river rose to 15.7 feet.

North of San Francisco, the Napa River rose Sunday to nearly 27 feet, or five feet above flood stage, which was just three feet short of the record flood in 1995.

The storm was California’s second major atmospheric river event in less than a week. Between Sunday and Thursday, about five feet of snow fell on mountain peaks west of Reno.

Nearly half of California remained under flood watches and warnings Monday afternoon, the next storm forming over the Pacific Ocean and heading toward land. Another round of rain and snow is forecast through Thursday, after which things should dry out for the weekend.

Forecasters are calling for another round of heavy snowfall in the coming days, with between four feet to eight feet of powder expected to drop above 7,000 feet and two feet to five feet predicted on the shores of Lake Tahoe.

Fritz and Shapiro reported from Washington. Sage Sauerbrey contributed to this report from Truckee.