I'm not sure if this is to be classified as an "avalanche," but after descending the Hypodermic Needle in foggy conditions, I skied too close to the base of the rocks skier's right of the couloir. The entire snowpack collapsed, giving way to a massive rock-well. I luckily landed on the edge of the snow and all my gear remained on top as well. Had I fallen into the bottom, this could have easily been catastrophic. Given the foggy conditions, it is unlikely that my partner would have seen me go in. After ten years in the backcountry, this is the first time something like this has happened to me. It serves as a reminder to give cliffbands and trees a wide berth and to travel with caution in areas with glide cracks.

Photo attached of the opening. Prior to me skiing across, the entire well was covered in a snowbridge. I landed prone on the edge, bottom of the photo.