Quick report
A welcome 18 inches of new snow greeted us on our arrival at Donner Summit this morning. Snowfall rates ranging from 1 to 2 inches per hour had increased the new snow amount to 24 inches by noon. Warming was rather gradual and had not had the effect of creating instability prior to our departure from the area at 1 pm. We were anticipating that this warming would be a significant driver of instability today.
Wind drifting and wind loading were substantial, but the wind had more of a south direction to it today and wind loading was less efficient than with our more typical SW to WSW storm wind direction. We kicked at the top of several avalanche start zones with no results. We ski cut one inefficiently wind loaded test slope, also with no results. Ski cutting across the top of some steep slopes below treeline, we were easily able to trigger hybrid dry/wet loose avalanches failing within the storm snow.
It very much felt as if we should be able to trigger slab avalanches out there today, but none occurred in the avalanche terrain/trigger points we felt we could engage with safely.
Dry loose avalanches were easy to trigger in steep terrain.Weather
- Cloud Cover
- overcast
- Wind Loading
- moderate
- Rain Elevation
- At 1 pm, 7,000
- Recent Snowfall
- At noon, 60
- Snow Avail For Transport
- large amounts
Snow level near 6,000' to 6,200' at 9 am had risen to 7,000' by 1 pm.
Snowpack
The Feb 3 rain crust is 10 cm thick and K hard at 8,050'. There was a layer of needles and rimed needles below it that contributed to an ECTP-26 result and PST end result on column isolation. It would certainly take a massive load to collapse the Feb 3 rain crust at this elevation. It would be easier at higher elevations where the crust is thinner. The Jan 31 buried near surface facet layer was buried another foot below the Feb 3 rc. The Jan 31 nsf layer was still F hard, but moist to wet.