Granstrom lives in Lake Stevens , north of Seattle , and skied for the first time when he was two years old. He competed in his first races at the age of five in the Stevens Pass ski area . In 2003, at the age of twelve, he won the slalom and giant slalom in the Whistler Cup , a youth competition for children aged 11 to 14. Two years later he won the slalom again. After reaching the age limit, Granstrom contested his first FIS races in December 2005 as a 15-year-old, his first victories followed in February 2007. After being accepted into the junior squad of the US Ski Association, he has also been in the north since the 2007/2008 season. At the start of the Cup . He achieved his first top 10 placements in this racing series in winter 2008/2009 . Granstrom took part in the Junior World Championships twice. While a 19th place in the Super-G was his best result in 2009 , in 2010 he won the gold medal in combination with a seventh place in the slalom, eleven in the giant slalom and 15 in the downhill.
In 2010 Granstrom rose from the junior to the C-squad. On November 14, 2010, he first took part in a World Cup race in the Levi slalom , but failed to qualify for the second round. Less than a month later he won his first race in the Nor-Am Cup, a great combination in Panorama . With a further six podium places, he achieved second place in the overall and slalom classification, third place in the super combination classification and fourth place in both the Super G and giant slalom classifications in the 2010/2011 season . In April 2011 he became the American slalom champion. On January 22nd, 2012, Granstrom won World Cup points for the first time by finishing 24th at the Hahnenkamm Slalom in Kitzbühel . In the 2011/2012 season , he made it onto the podium in three slaloms in the Nor-Am Cup , placing him fifth in the discipline ranking and eighth in the overall classification.