I was watching multiple parties shuttle each other to the top of the east facing chutes of peak 12,700’ (Guide Peak) via snowmobiles. They were taking a road that had been established by a snowcat operation around the lower angle southern shoulder to access the chutes. As clouds began to move in and the light became "flat" the groups left the area. At 12:26 pm I was alone on the apron and heard what sounded like a fighter jet flying low overhead. I was looking at the Guide Peak chutes and suspecting an avalanche I watched as the entire face cracked and released. I didn't see anyone on the slope prior to the sound and during or after the release. Assessing the size and speed of the debris I quickly moved out of the runout zone. I had radio contact with the guides of the snowcat operation and immediately notified them of the slide. That terrain had been closed operationally by the guide team and they were not in danger. Once the debris had stopped moving, I started a beacon search and radioed to the cat driver to call 911. I was quickly joined by 2 recreational snowmobilers and 4 of the snowcat guides. We discussed the possibility of someone being in the slide and determined that based on all our observations no one was caught. The 7 of us searched the debris field for about 45 minutes with no beacon signals or signs of anyone being caught and no reports of anyone missing or caught. After further discussion with the cat driver and the guides we determined based on the timing of the snowcat movement on the low angle shoulder near the chutes, the snowcat most likely remotely triggered the avalanche. Clear Creek Sheriff and Alpine Rescue also staged to assist after making contact with them a few minutes after the slide was reported. Jones Pass Guides were on scene for the search.

Standing on the apron of peak 12,700' (Guide Peak)