The search for a California backpacker who went missing in Sequoia National Park is entering its third day.

Bill Roberts of Lake Tahoe was reported missing Saturday, when he was supposed to meet up with family members at Bullfrog Lake after a three-day solo backpacking trip along the John Muir Trail, according to a statement by the National Park Service.

The 76-year-old's family had dropped Roberts off Wednesday at the Cottonwood Pass trailhead, which goes to a portion of the Golden Trout Wilderness in central California's Inyo National Forest, park service spokeswoman Rebecca Paterson said in a news release.

Roberts was carrying a GPS tracker that allowed his family to follow his progress, but the tracker stopped giving updates when he was near a ridgeline of Caltech Peak, which is just over 13,800 feet in elevation.

Paterson did not immediately respond to a question Monday about the last day the tracker pinged.

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It's unclear whether the GPS updates stopped because the tracker was turned off, it lost signal or because of another reason, she said.

Tracks found

Search crews began looking for Roberts in the area where the GPS tracker last pinged and found some of his tracks on Sunday, she said.

Roberts, who was on his first solo overnight backpacking trip, had intended to pass through areas that are still covered with snow and creeks that have unseasonably swift waters, she said.

Paterson did not immediately respond to a question about whether Roberts had mountaineering experience or gear.

Search effort hampered

The conditions in the area, paired with heavy rain and thunderstorms over the weekend, have hampered search efforts both on the ground and in the air.

Officials said that three ground teams, a drone crew and helicopters were deployed help the search Sunday and that similar efforts would continue Monday.

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Roberts is white, 6 feet, 1 inch tall and has a slim build, with gray hair and a full gray beard. He was last seen wearing a brown and black long-sleeved shirt, tan hiking pants, and a brown brimmed hat, and carrying trekking poles and an orange and black backpack.

Though he has some backpacking experience, this was his first solo overnight trip, Paterson said.

The park service asked that anyone who has been in or around the area of Roberts’ planned itinerary since Wednesday to contact Sequoia and Kings Canyon National Parks at the tip line, 888-653-0009, whether or not you believe that you saw him.