Debris from a very large natural avalanche (D4) that ran on 12/23 filled Clark Canyon down to 5400ft. The debris was likely 30-40ft deep in places. There is high confidence in the timing of the avalanche as USGS seismic monitoring equipment on Mt Hood detected the avalanche around 8am on 12/23. The general area where the top of the avalanche would have been was obscured by clouds, and a crown was not observed on 12/28. Mt Hood Meadows Ski Patrol have evidence to believe the icy bed surface of the 12/23 avalanche was the same bed surface in other avalanches this season. Avalanches may have run on this bed surface as early as 12/14. The 12/23 event was the largest avalanche.
Unknown crown dimensions. The start zone was likely between 8500-10500ft and debris ran several thousand feet with the terminus around 5400ft in Clark Canyon.