GRASS VALLEY, Calif. - A low-pressure system brought snow in the Sierra along with saturating showers and threats of tornados to the Sierra foothills Monday.
A tornado warning was issued for southwestern Nevada County by the National Weather Service, beginning at 3:37 p.m. and continuing until 5:45 p.m., said Karl Swanberg, forecaster with the National Weather Service.
At about 5 p.m., the weather service reported a severe thunderstorm capable of producing a tornado about seven miles west of Lake of the Pines, moving northeast at 25 mph. The storm's path included Lake of the Pines, Alta Sierra, Cedar Ridge, Grass Valley and Colfax, the weather service reported.
Meteorologists originally had detected a rotation in clouds in a thunderstorm system six miles southwest of Hammonton, an unincorporated community in Yuba County, Swanberg said.
The tornado warning affected Lake Wildwood, Smartsville, Marysville and Beale Air Force Base until 5 p.m., Swanberg said.
A tornado touched down north of the state capital Monday afternoon, but only minor damage was reported, the Associated Press reported. The National Weather Service in Sacramento says it had no reports of injuries from the tornado.
"We've had reports of power lines down and some outbuildings damaged," meteorologist Eric Kurth told the AP. "Some kind of a small outbuilding was lifted about 200 feet from where it was located."
A tornado reportedly was spotted at about 3:15 p.m. near Yuba City, about 40 miles north of Sacramento and 35 miles west of Grass Valley.
The tornado also caused damage to the Mallard Lake Golf Center as the first storm of the season moved through Northern California, he said. No one was answering the telephone at the golf course Monday afternoon.
Kurth said the reports were confirmed by Sutter County sheriff's deputies and firefighters.
"We've heard about trees being downed, power lines being downed, no injuries," he said.
Several funnel clouds also were reported north of Sacramento, but Kurth said there were no other reports of touchdowns.
The storm system also brought large amounts of rain to the region.
While the heaviest batch of precipitation occurred overnight Sunday into Monday morning, scattered showers are expected to persist until Wednesday night, Swanberg said.
Another bout of heavy rain is expected Wednesday, Swanberg said.
Higher elevations in the Sierra saw 2-foot snow accumulations Monday, and eight to 16 inches were expected in elevations between 5,000 to 7,000 feet, Swanberg said.
Around noon Monday, Amelia Richmond, spokesperson for Squaw Valley Ski Resort, reported about 12 inches of accumulation in the higher elevations at the resort.
Snow accumulation on roads wrought havoc for commuters Monday, as Highway 20 between Nevada City and Interstate 80 was closed for much of the morning, according to traffic officials.
The chaos began shortly after 5 a.m. when a vehicle was reported to have spun out in the higher elevations of the foothills, about 16 miles northeast of Nevada City at an estimated elevation of 5,000 feet, according to the California Highway Patrol traffic incident website.
Within an hour, the roadway near the Highway 20 intersection of Omega Road was completely blocked as semis and other vehicles also succumbed to the road conditions, said CHP Spokesman Marc Morrison.
No injuries and minor fender benders were reported.
With as much six inches of accumulated snow, CHP closed Highway 20 between Interstate 80 and Nevada City for several hours as snow plows cleared the way for traffic that was redirected, according to Morrison.
"It's snowing like crazy," Morrison said shortly before noon. "They got up there, and no one could go any further."
Once snow plows cleared the road and the vehicles were pulled from the snow, Morrison said the road was reopened shortly before noon but only for vehicles that had chains affixed to their tires or four-wheel drive vehicles, Morrison said.
The weather pattern is expected to begin to dry out Thursday into the weekend, with warmer temperatures returning and highs predicted to hit the high 60s and low 70s in the latter portion of the week.
"This is the first significant moisture for much of the Sierra," Swanberg said.