We found 2.5' of new snow that had fallen since 1/3, with more than half of that likely falling in the past 24 hrs. Warming temps had moistened the top few inches of the new snow (at least at low and middle elevations), creating a density inversion near the surface. The new snow and inversion made for challenging travel conditions, which prevented us from getting as far as we hoped - we did not reach the upper elevations to assess wind loading. New snow + rapid loading + wind + warming = unstable avalanche conditions. Most dangerous conditions would be found in any wind loaded terrain, but any steep slope is suspect given the amount of new snow and warming temps.
S1-2 while we were out from 1030-1530. There was 5cm new on the sled trailer when we returned. We had 3cm on our sleds while we were gone from 1200-1330. We had light winds at low and middle elevations.
Along highway near 4th of July creek
||D1||N-Natural||Wind slab failure on valley bottom wind roll beneath cornice. Looked to be a few feet deep but only ran about 20 feet due to the shortness of the slope.||None|
We had poor visibility
In addition to warming surface and density inversion, there seemed to be a few instabilities within the storm snow. However, we received no significant results in snowpack tests or ski cutting a small slope. With a very steep slope, or with some wind effect, all bets would be off.
@8100', S, 30*: HS 170. No October snow, and no significant layering at the 1/3 interface or anywhere below that. We only got ECTN results.
Layer Depth/Date: 20-60
Comments: It was difficult to asses storm instability without steeper terrain. Rose indicates observed terrain.
The storm is adding rapid weight to 12/11, which is likely down 2m or more - we did not observe it. I'm fairly certain wind slab were a major hazard at upper elevations.
Our terrain use was limited by the snow depth and trail breaking. In our trip plan, we closed wind-loaded avalanche terrain and sheltered terrain over the low 30s. That felt like a good plan based on the conditions we saw.