Let's pray for his safe return. His children are camping out in that area that he is missing in the hopes to find him. http://www.katu.com/news/11114156.html McKENZIE BRIDGE, Ore. (AP) - Searchers for a University of Oregon mathematics and statistics professor missing in the Cascade foothills since Sunday raced expected worsening weather Thursday but reported no new clues. Daming Xu, 63, told his family he was going on a day hike alone in the foothills near the Three Sisters Wilderness Area. Lane County Sheriff's Capt. Bill Thompson said the number of on-ground searchers increased from 26 to about 40 on Thursday. He said search dogs were used at one point. Searchers say the region has ample water and shelter, but temperatures are expected to drop. Thompson said a weather system was moving in from the west and could result in colder temperatures, mist or rain and possibly snow Thursday night. He said the district has some rugged areas, but most of it is accessible to people who have some experience and are in good condition, which made the area east of Eugene popular with hikers. Xu's daughter, Xin Xu of Portland, said her father is healthy, rides a bicycle to work and is a frequent hiker but embarked on a longer-than-usual route Sunday. She said he probably was wearing only a long-sleeved shirt but might have been carrying a lightweight jacket. A heavier coat and trail guide were found in his car at the trailhead, about a three-hour hike from where he was last seen Sunday afternoon. "We think if he's not hurt, he should be OK," his daughter said. At least three university faculty members have joined the searchers, some on horseback. Two Oregon National Guard helicopters, one with infrared, heat-seeking capability, and a Civil Air Patrol plane joined the search earlier. Two hikers told authorities they saw Xu at the summit of Olallie Mountain about 1:30 p.m. Sunday and talked with him briefly. They said he may have had a small backpack. They said he headed back down and they soon followed. His car was still in the parking lot but they said they did not see him. Searchers found what they believe to be Xu's footprints on Tuesday afternoon and followed them until early Wednesday, when the prints ended in an area known as Bear Flat. Bear Flat is described as an open area but adjacent to steep canyons. "If a person has any kind of wilderness survival skills, they could make it, said Lane County Sheriff's Lt. Randy Smith.