Despite days of searching by several law enforcement agencies, there is still no sign of a Nevada couple who left a Sacramento suburb last week during bad weather on a drive that would've taken them through some of the Sierra Nevada's higher elevations, authorities said late Tuesday.

Roderick Paul Clifton, 44, and Paula Lane, 46, had driven to suburban Citrus Heights to visit relatives. They left Thursday afternoon to return to their home in Gardnerville, Nev., said Citrus Heights police Officer Bryan Fritsch, a department spokesman.

The couple began their trip in their dark blue 1989 Jeep Cherokee about the same time a major storm was moving into the area.

It's believed the couple drove along Highway 50, a route that would have taken them through Echo Summit, a mountain pass at an elevation of about 7,300 feet, Fritsch said.

Clifton and Lane frequently made the drive, and usually Clifton would call relatives to let them know they had made it over the summit, Fritsch said. But during last week's trip, no call ever came, and nobody has heard from the couple.

Relatives are worried that the bad weather — including heavy snow in the mountains — may have played a role in the couple's disappearance, Fritsch said.

"The concern is that they had left just before weather conditions became really bad," Fritsch said.

The drive from Citrus Heights to Gardnerville is about 120 miles, a good portion of it on Highway 50, a steep and winding roadway through the Sierra.

"It can be pretty treacherous traveling that way," Fritsch said.

Police say neither Clifton or Lane — who has two 11-year-old boys in Garnerville — have a history of disappearing, and calls to their cellphones have gone answered.

Both phones appear to be turned off. And with reception through the mountainous area spotty, investigators have been unable to electronically track the couple's whereabouts, Fritsch said.

Deputies from El Dorado and Alpine counties, the California Highway Patrol and Nevada authorities are also taking part in the search.