Increasing Instability and Avalanches on Andesite Peak

Before leaving the office we made a tour plan to stay in low angle terrain with no exposure from above. Driving up I80, we saw obvious signs of wind loading including blowing snow and newly formed cornices along the side of the road. Upon arriving at the Castle Peak Snopark, we found 16-17 inches of new snow in the parking area. It was cloudy and snowing lightly. Once we started skinning, we could feel the old weak snow below the new snow with our poles. We stopped and did a quick Extended Column Test (ECT) on the side of the skin track. It failed while we were preparing the test. We continued up towards Andesite sticking to low angle slopes. Even though there was already a skin track, we frequently stepped off of it to probe and do quick hand pits. We continued to find the old weak snow buried below 1-2 ft. of new snow. During one of our forays off the skin track, we felt a small whumpf in a below treeline meadow.

As we ascended into more exposed near treeline terrain at 11 am, the winds increased and it started snowing harder. We found small sensitive wind slabs on wind loaded test slopes. These wind slabs failed in the storm snow and remained less than 6 inches deep on the test slopes that we looked at.  On one of the test slopes, a second ski kick on the ridge after the wind slab released triggered a large whumpf as the old weak snow 18 inches to 2 ft below the surface collapsed. We descended a low angle sheltered slope and came back to our previous skin track to see how much snow had accumulated in the last hour. We found 2 to 3 inches of snow in the skin track. As we gained the ridge on our second lap, winds and snowfall increased again and we experienced some periods of white-out conditions. Near the top of Andesite, we ran into another party who had ski cut 2 wind slab avalanches on previous laps. They said that the crowns had gotten bigger and the second one they released was about 1 foot deep. They ski cut a third one shortly after we parted ways and it was also about a foot deep.  Again we chose to stay in low angle sheltered terrain on the way down. As we were skiing out widespread cracking started to occur in the upper 3 to 5 inches of the new snow in below treeline terrain. By the time we got back to the trailhead 3.5 hours after we started 8 inches of new snow had accumulated indicating snowfall rates of more than 2 inches per hour at times.