Quick report
Recent moderate winds have taken a toll on the snowpack in areas near Thompson Pass Summit. Evidence of this includes raised ski tracks, hard winboard surfaces at all elevations, and some thick windslabs on south-facing slopes. One of these slopes produced a human-triggered slab avalanche in the last 24 hours. The slab measured approximately 150 long, ran for 70 vertical feet, and had a crown thickness of 10-60cm. Various pits were dug at the flank and into the crown to determine the failure surface. (See snowpack summary)
Weather
- Air Temp
- Not observed
- Cloud Cover
- few
- Wind Loading
- none
- Recent Snowfall
- none in almost 2 weeks
- Snow Avail For Transport
- none
Warm and sunny conditions with a few clouds and light breezes. Snow has been previously wind affected at all observed elevations with no snow left for transport. The snow on sunny slopes was begining to soften just after noon.
Snowpack
All areas that I trevelled had been affected by moderate winds over the last few days. There were patches of soft, chalky snow here and there, but the area was mostly void of unconsolidated powder. 2mm surface hoar was present through all observed areas. There was also a dusting of rimed precipitation particles on the surface. A recently triggered wind slab avalanche (D2-) was observed to have a thickness of 10-60+ cm. Snow pit analysis adjacent to the slide revealed a sun crust bed surface with facets on top acting as a weak layer. Pit tests in an area where the slab was thinner included ECTP11 down 14. Several quick pits and shovel shears were performed at various depths up to 1M in search of intact buried surface hoar, but none was found.