(Tacoma, WA)  --  Officials say they've tentatively identified the body of a hiker who got lost on Mount Rainier after being caught in a storm during the weekend.  The body is believed to be that of 58-year-old Arvid Lahti of Norway, who's being described as an experienced climber who scaled some of the world's highest peaks.  The body was airlifted off Mount Rainier yesterday to the Pierce County Medical Examiner's Office, who will officially determine the man's identity.  Crews had been trying to reach the body since Sunday.