Visibility on Mount Rainier was limited on Thursday.
Ten rescuers were making their way up Mount Rainier on Thursday, braving stormy conditions to search for four overdue campers and climbers.
The team plans to search the intended route of the two parties by trekking from the Paradise Visitor Center to the Muir Snowfield and then to Camp Muir, where they intend to spend the night, the park service said in a statement.
"The team is made up of highly skilled mountaineers who are familiar with the route and in mitigating associated avalanche exposure," the park added. "A helicopter is on standby ... awaiting favorable flight conditions, although freezing rain is precluding flight operations today."
The search party reported back that the snowpack was firmer than on Wednesday, making for an easier search, but the park service said the effort would be suspended if conditions become unsafe.
"The weather is the greatest challenge to search efforts at this time," stated incident commander Kelly Bush.
The two campers who were due out Sunday had planned to stay on the snowfield, while the climbers due out Monday had planned to summit the mountain.
"Although both parties are equipped for winter camping, concern for their well being grows each day due to their dwindling food and supplies," the park stated.
The campers are Mark Vucich, 37, of San Diego and Michelle Trojanowski, 30, of Atlanta.
The climbers are a couple from Springfield, Ore., who have not been named.
Rainier averages about two mountaineering deaths a year.
Late Monday, a lost snowshoer was rescued after spending two nights on the mountain.
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