In the Skyrunning World Series Forsberg has been especially successful in the Ultra Series where she won every race in 2013-2015 except for the 2014 Trofeo Kima where she took a wrong turn when four hours into the race and half an hour below the course record time; she descended 500 meters and had to ascend again, losing one hour, then worked her way back up the field to 2nd position.