An Eldora Mountain Resort employee never returned home from work on Sunday afternoon.
Ryder Johnson, 20, was last seen leaving work at 3 p.m. that day. A Boulder County Sheriff's deputy found his vehicle near Gross Reservoir on Flagstaff Road at 10 o'clock that night.
Dozens of rescuers from multiple agencies searched around Gross Reservoir and Walker Ranch Open Space area on Monday morning. A helicopter was included in the search, but searchers found no sign of the Lafayette man.
Emergency crews will begin looking again on Tuesday.
The Boulder County Sheriff's Office asks anybody with information about Johnson's whereabouts to call 303-441-4444.
He is described as a white male, 5 feet 10 inches tall, 155 pounds, with brown hair and brown eyes. He was last known to be wearing a red and black coat with an Eldora Ski jacket and black pants.