Avalanche: Hatcher Pass

After transitioning, we crossed a few feet above a "whale's back", and continued a few hundred feet below the ridgeline. About 50 yards past the whale's back, we saw avalanche debris travelling downslope and into the creekbed. The crown was about 15 feet below our ski tracks that were above the "whale's back". We did not have any red flags prior (no shooting cracks, no whoomphs, no crowns), and did not hear the avalanche. It appeared that the slab started relatively small, but the debris collected surrounding snow as it ran toward the creekbed. The debris continued moving quickly in the creekbed. We continued forward to get a better view of the area below and determined that there were no other people in the area of the creek. We did determine that an area we had previously thought was wind affect was likely old debris from a small wind slab on a more southern aspect of the bowl, but it did not appear to be recent.

Traveled back the way we came, and determined with a probe that the "whale's back" was a wind created feature, kind of like a cornice, but on terrain that doesn't provide an opportunitiy for much overhang. We did not see any cracks connecting our ski tracks to the crown, and estimate that our weight created a wedge type of feature, pushing the snow underneath the "whale's back" and triggering a wind slab to release. No other signs of instability on the ski out, just lots of variable snow surface quality.

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