The Winter Olympics are over for Girdwood snowboarder Callan Chythlook-Sifsof.

She fell on both her qualifying runs today and failed to advance to the quarterfinals in the women's snowboardcross.

On a day when visibility was often nonexistent because of thick fog at Cypress Mountain, Chythlook-Sifsof did not finish her second run and posted the day's slowest time in her first run.

The boarders with the top 16 times in either qualifying run advanced to this afternoon's quartfinals. Both of Chythlook-Sifsof's American teammates advanced, including Lindsey Jacobellis, who had the second-fastest qualifying time.

Mellie Francon of Switzerland had the fastest qualifying time -- 1 minute, 24.43 seconds, registered on her first run. Jacobellis' best time, 1:25.41, came on her second run.

Chythlook-Sifsof completed her first run in 1:59.09, slowed by a fall. She fell again on her second run and did not finish

Rain and thick fog postponed the first qualifying run by two hours and interrupted it on a couple of occasions.

Chythlook-Sifsof, 21, is the first Alaska Native to compete at the Olympics.