Avalanche on the W to WSW facing aspect of the Brighton Back Bowl (elevation: 9800) appeared to run in the early morning hours and possibly as late as 900 hours. The debris indicated that the slide ran when the surface snow was still damp and or saturated from the overnight rain and high temperatures. Debris piles had wet slab runnels, piles, and tunnels from channeling. Debris was at least 5 feet deep and had run at least 300 feet in length. Starting zones ranged from 42 to 37 degrees with a crown face and flanks of at least 12 inches. Width was approximately 300 feet. It appeared that the initial weak layer was near surface facets that were the upper 4 to 6 inches of old snow surface prior to the new snow and rain that came in on Saturday evening. Of note: it appeared that once initial failure occurred the slide stepped down in several areas connected to the steep cliff bands where it was able to pull out depths of up to and slightly over 2 feet. The weak layer here was facets below the December Rime crust. This weak layer of facets was up to at least 2cm of 4 finger snow with harnesses of at least one finger directly above and containing the Rime Crust.