Details in the preliminary report are from a party that witnessed the avalanche and the skier that triggered the slide. CAIC staff examined the avalanche the following day, but the crown was unsafe to approach for a detailed profile.
The skier reached the summit of Torreys around noon. He dropped into a very exposed and committing line to the skier's right of Dead Dog Couloir and dug a pit. He reported moderate test scores with average shears (CT15 Q2) at the base of the recent windloaded snow. The skier saw no additional signs of instability with a ski cut in Dead Dog Couloir and "kicking snow around" the top of his line. The skier began his descent.
The slope fractured on the skier's third turn. He was left standing on the crown of a 10 inch deep avalanche. "Little sections of slabs kept sliding" as the fracture propagated outwards.
The avalanche was a SS-AS-R2D2-I, a soft slab, skier triggered, small relative to the path, capable of burying a person, and ran on the interface between recent and older snow. The crown appeared to be anywhere from 8 to 20 inches deep, and was made up of several small, recently windloaded pockets that created a complicated fracture line. The avalanche began in very exposed, very complicated, and obviously windloaded terrain near 14,200 feet with a generally east aspect. The avalanche ran over 1200 vertical feet, over several large cliffs and rock piles. The deepest debris was about 1 meter. There was a similar sized avalanche in Dead Dog Couloir, probably triggered sympathetically by the first avalanche. The witnesses reported numerous shallow, natural avalanches, including on the slope the skier attempted.
The witnesses heard a faint "HELP!" They changed plans and headed toward the summit of Torreys. The skier stood at the crown for 20 to 30 minutes before climbing back to the summit and the saddle between Torreys and Grays. Once the witnesses were within shouting distance, they determined that the skier was uninjured and alone. The skier proceeded to hike down, cutting across snowfields that the witnesses had "assessed [as] way too dangerous to touch."
The CAIC morning forecast for February 15 noted that "winds have been drifting the new snow into lee and cross loaded terrain and some shallow avalanche activity has been reported over the last 24 hours... [on] NE-S aspects near and above treeline." The avalanche danger was "CONSIDERABLE above treeline on N-NE-E-SE-S aspects."
The skier left the trailhead before the February 15 forecast was issued. He had checked the forecast on February 14, when the forecast danger was MODERATE on east aspects above treeline. Both the forecasts on February 14 and 15 noted that "...although the slab formation has been thin, in complex terrain even these smaller avalanches can ruin your day."
Logan and Trautman 20090217