A search for a missing 22-year-old hiker in the Trinity Peaks area of southwestern Colorado has been temporarily suspended due to hazardous weather conditions.

The search for Daniel Lamthach, of Salt Lake City, was suspended on Wednesday and a flood watch has been posted for the area until 10 p.m. Thursday, according to the San Juan County Office of Emergency Management.

Lamthach has been missing for 12 days. He was last seen in the Molas Lake area where he had planned a trail run, according to emergency responders. He was unprepared for an overnight stay in the wilderness.

On July 21, a concerned friend reported Lamthach missing and a search and rescue operation was initiated with air support. His vehicle was located in the parking lot of the Molas Lake trailhead. Earlier, on July 18, hikers on the Elk Creek Trail at the Vestal Peak trail confluence found Lamthach’s cell phone. The search effort has included airplane sweeps of the rugged and remote area.

Lightning has been intense during recent afternoon thunderstorms. The National Weather Service has issued a flood watch for the San Juan Mountain on Thursday.

“We have had to suspend operations due to severe weather and the danger it presents to our teams,” said Tyler George, director of Silverton Medical Rescue, in a statement. “We are privileged to have some of the finest mountain rescue technicians in the state, and without their skill, expertise, and dedication, we would not have been able to even approach the area due to the conditions and terrain.”

Personnel searching for Lamthach have put in more than 800 hours, with nine hours logged by helicopter and 12 hours of airplane surveillance. Fourteen ground crews have searched a widespread area, including sunrise to sunset efforts. Other than the phone, there have been no signs of Lamthach. Search operation leaders have met with the Lamthach family about future efforts.