It was a typical overcast winter morning at Portland International Airport in Oregon, with ceilings running around 1,400 feet agl and reported tops at about 7,000 feet msl. Ground control had just rattled off our clearance to Rogue Valley International in Medford, Oregon, clearing us to 10,000 feet. There had been no pilot reports of icing. The briefing called for conditions to remain overcast with ceilings around 1,200 feet. Deteriorating conditions and possible snow were forecast for later in the day, but well after our estimated arrival time.