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Search spokeswoman Susan McBurney said officials may have to consider calling off the search if no trace of Dan Walker is found.

He was last seen Sunday when he separated from his wife and daughter to seek help after they got lost on a backcountry outing. They were later found.

Although skies have cleared, temperatures are only reaching the teens during the day, and dropping below zero at night with wind chills as low as minus 19. Temperatures were forecast to rise slightly this weekend, but more snow also was likely.