Ice conditions good - Avalanche situation considerable

We were climbing the second last pitch of Polar Circus when spin drifts started to get bigger. So we decided to turn around. When we wanted to rappel over the pencil (around 2000 meters above sea level) a avalanche around size 2 caught us. It must have strated in alpine zone. The debris was loose but due to the narrow gully above us pretty heavy. We were in the avalanche for around 30 seconds. Breathing was difficult. Luckily we were at a hanging belay so none of us got burried. We could then descend with no further incident. The most logical explanation to us is that the strong wind at high altitude caused the drifting snow avalanche.