Wester has been participating in competitions on the AFP World Tour and the FIS since 2010 . At the end of March 2012 he became the Swedish Slopestyle Champion. In January 2013 he started the World Cup in Copper Mountain for the first time and finished 51st in Slopestyle. This was followed by fourth place in Silvaplana and second place in Sierra Nevada and thus reached third place in the Slopestyle World Cup. At the Freestyle Skiing World Championships 2013 in Voss , he took seventh place in slopestyle. In the 2013/14 season he won the SFR Tour in Val Thorens and La Clusaz in slopestyle and at the Jon Olsson Invitational in Åre in Big Air. At the 2014 Winter Olympics in Sochi , he came in 18th place in slopestyle. In the following season he triumphed again in slopestyle at the SFR Tour in Val Thorens and in Big Air at the One Hit Wonder in Thredbo . At the Winter X Games 2015 in Aspen , he finished 12th in slopestyle. After ninth place in Cardrona and seventh place in Stubai at the beginning of the 2017/18 season, he finished second at the Big Air World Cup in Mönchengladbach . At the following World Cup in Font Romeu , he won his first World Cup victory in slopestyle. At the Winter X Games 2018 he took eighth place in slopestyle and at the Olympic Winter Games 2018 in Pyeongchang he came 11th in slopestyle. In March 2018 he became Swedish Big Air Champion and at the end of the season he finished 17th in the overall World Cup and third in the Slopestyle World Cup. In May 2018 he came ninth in Big Air at the X-Games Norway in Fornebu .
Sweden