PORTLAND, Ore. — Poor visibility and avalanche danger limited the search Wednesday for a climber missing on Oregon's Mount Hood.

Kinley Adams, 59, of Salem, has been missing since Saturday. Since then, search and rescue crews have been persistently thwarted by white-out conditions, and the skies were not expected to clear until Thursday.

Thick fog delayed the start of Wednesday's search until late morning. The dangerous conditions kept crews searching canyons near the timberline, away from the higher elevations where they believe Adams is likely to be found. An Oregon National Guard helicopter was on standby.

"The big break will be if we can get enough visibility to get aircraft up and do a visual search of the upper mountain," said Mark Morford, a spokesman for Portland Mountain Rescue, one of the volunteer organizations helping the Clackamas County Sheriff's Office.

Morford said a reconnaissance team joined searchers Wednesday, assessing whether the avalanche threat has diminished enough to put searchers on the snow at higher elevations.

"Quite a few slides have been noticed, so that's probably our biggest risk right now," he said.

Adams, a dentist, is an experienced climber who has scaled numerous peaks since the 1970s. His family and search crews said that gives them hope he is alive in a snow cave, waiting for help. In March, injured Mount Hood hiker Mary Owen survived six days in a hand-carved snow cave before her rescue.

"He knows how to survive," Adams' wife, Lorraine, told reporters earlier this week. Said Morford, "We still look at this as a rescue, you bet."

Adams has recently been making frequent visits to Mount Hood in preparation for a climbing trip to Nepal. He was due home Saturday afternoon and his family called for help at 9 p.m. His vehicle was found on the mountain at Timberline Lodge.

Fifty miles east of Portland, Mount Hood is a popular climbing site that has seen dozens of accidents and fatalities. Thousands climb the 11,239-foot peak each year, mostly in the spring. Summer can be a risky time to climb because warmer temperatures melt the ice and loosen rocks.