COOPER SPUR, Ore. (AP) _ Cold rain lashed the base of Mount Hood on Wednesday as search parties headed back up the treacherous slopes to look for three climbers missing since the weekend.

A fresh team was joining the search Wednesday, and crews may get some help from heat-seeking, unmanned aircraft provided by a Colorado company and pinpoint cell phone detection equipment from another high-tech company, said Pete Hughes of the Hood River County Sheriff's Department.

Because of poor weather at higher elevations, searchers focused on the mountain's lower canyons on the chance that two climbers who are believed to have gone for help got that far.

``But if anybody is above the 7,000-foot range, we're not going to be able to get to them,'' Hughes said. ``And we're probably not going to be able to get to them by Thursday either, unless there happens to be a break in the weather.''

Even at the base camp at Cooper Spur, the wind hit 60 mph Wednesday morning and temperatures hovered in the 30s. At higher elevations, the teams have faced wind so strong it knocked them off their feet, plus poor visibility in blowing snow and a threat of avalanches. More stormy weather was in the forecast.

``Man and machine are at their limits there,'' said Capt. Christopher Bernard of the Air Force Reserve's 304th Rescue Squadron.

Plans called for two staging camps on the north and south sides of the mountain so teams can head to the summit quickly if the weather breaks, Hughes said.

There had been no contact with the missing climbers since Sunday, when one reached his family by cell phone to say he was in a snow cave high on the mountain and his two companions had gone for help.

The rescue effort was hampered because the three climbers had taken one of the most difficult approaches to the summit, scaling the north side of the mountain where slopes tilt at angles of 50 or 60 degrees and feature become sheer walls of ice.

Higher flanks of the mountain have been scoured by wind up to 80 mph.

Kelly James, Brian Hall and Jerry ``Nikko'' Cooke had planned a ``quick climb'' on Mount Hood, traveling light to make the ascent as fast as possible, officials said.

Cooke, 36, a lawyer from New York City, and Hall, 37, a personal trainer who played for the now-defunct Dallas Rockets professional soccer team, are believed to have attempted a descent while James, 48, a landscape architect from Dallas, apparently remained near the summit.

James has the most experience _ 25 years of mountaineering that includes Mount McKinley, the Andes Mountains in South America and peaks in Europe, his family said.

``My brother has been climbing for 25 years, and he would know what to do in a difficult situation,'' said Frank James. ``He's been in a number of situations and always managed to get out well. I think that's a testament to his experience.''

Frank James said it wasn't clear from his brother's four-minute cell phone call whether he was injured. His brother did appear to be feeling the effects of the cold and said he was worried about the weather, he said.