Jan. 10, 2018, 11 a.m. PST
Weather: Light snow in the morning with overcast skies gave way to broken skies, then overcast again with light snow in the afternoon. Light winds from the West.
Snowpack: HS about 200cm in the mid 4,000ft zone, 30-40cm new snow. Stepped out of the old growth onto a lightly wind affected slope on WSW at 4,600ft and whumph! Collapse on a small 30 degree slope. Found these were consistently occurring and collapses were ~15m in radius. Failure layer was within 1/9 storm snow and on top of 1/5 crust, down 35-45cm depending on locale. Found ECTPV, and CTV SP (failure upon isolation) on SE at 4600ft in an area that had not been wind affected on same layer, right above the 1/5 rain crust. Had a great day skiing quality powder by stepping it back, staying out of the wind zone, and not trusting anything steeper than 33 degrees. Photos: 1. Fracture caused by a collapse at 4,600ft on WSW. 2. Test site on SE at 4,600ft showing failure layer right on the 1/5 crust.
Area Description: South side of Union Peak
Observation by Matt Primomo
Did you see any avalanches? No
Did you trigger any avalanches? No
Was anyone caught in an Avalanche? No