Quick report
- Cracking
- specific
- Collapsing
- specific
Bitterly cold temperatures have yet to be pushed out of Thompson Pass. Small amounts of new snow from last week and last night are making surface conditions a bit more pleasing, but the snowpack remains weak, thin, and faceted in the areas we have been travelling. Locations where the 12/1 rain crust has been buried by windslab have created a persistent slab situation that remains sensitive in isolated to specific areas, especially on SW to NW aspects in mid-mountain elevations. Added stress from additional snow this week will likely increase the chances of avalanche activity associated with this setup.
Signs of instability were not dramatic, but the shalowly burried 12/1 raincrust/facet interface was obviously weak underfoot. Collapsing and cracking were mostly localized to the area travelled, with the exception of a couple of isolated collapses that propagated for a significant distance. Triggered one (D.5-) wind slab about 15cm deep when riding near a small 35-degree slope.Weather
- Air Temp
- -21 at Parking lot
- Cloud Cover
- few
- Wind Loading
- previous
- Recent Snowfall
- 4cm
- Snow Avail For Transport
- moderate amounts
On the drive up, there was an impressive 26 deg (F) difference between Moonlight Basin (6f) and the Gap at the top of the pass (-20f). The tour started with calm, mostly clear conditions and a temperature of -21F at the parking lot. Thin, low clouds and light snowfall moved in as the day progressed. A few centimeters of low-density snow that accumulated last night has been redistributed by light breezes.
Snowpack
Observations were focused on the upper snowpack where the 12/1 rain crust/facet interface lies under windslabs and storm snow of varying depth. This 2-3cm thick crust facet combo overlies a weak unconsolidated and faceted snowpack in elevations below 3000-3500feet. On specific leeward terrain, windslabs up to 1ft+ deep have been deposited on top of this weak setup, but have not applied enough stress to collapse the crust layer. This is causing a prolonged period of sensitivity that has been slow to heal. New snow forecasted for tonight and tomorrow will apply additional stress to the situation.