AdvisorySAAC04

02-20-05 Mt Troy - Showboat

We went out today to check the changes since our last fieldwork on Thursday. We found the snowpack continuing to settle, round, and gain strength. There have been no signs of instability for ten days now, and the steeps were not even sluffing today.

Some deep weaknesses remain, but it would take heavy and rapid loading now to release them. In the top 20 cm, there are some near surface facets that are still sugary and there is some large surface hoar on top. Both could form weak layers under the next snowfall.

There is some rime crust about 1 cm thick in places, too. We did not find much of the rime crust in the Mt Troy and Showboat areas today, but did find a sun crust on the more southerly aspects. It grabbed edges on the SW side of every little bump, while the snow was slightly faceted powder on the NW side. The sun and rime crusts may not bond well to new snow when it comes.

Trevor Joyce shears the AK Block after multiple hard jumps (AK6 Q3) on 36°. The initial fracture was on the denser rounds at 182 cm, about 35 cm below the surface, and then it fractured to the Jan 29 - 30 crust and facets at 124 cm, 92 cm below the surface. The breaks were irregular and the slabs lacked energy.

Trevor shears the Rutschblock on the same layers at the same values as the AK Block (RB6 Q3) on 36°. The breaks were even more irregular than on the AK Block test.

Shaded aspects had good shallow powder today. Micro terrain features made all the difference. Any slight sunward angle to the slope made it crusty, even a few degrees northward made it powdery.

Trevor cranks a turn on the lower slopes. Tracks from recent sunny days had frozen chunky snow along them, while the adjacent snow was soft. It is likely that faceting on the recent clear nights recrystallized the unpacked snow, loosening it, while the compacted snow's density slowed the recrystallization process so the chunks stayed hard.

All runs in the Showboat area end in challenging gullies and brush. These are the runouts of the large avalanche path above. None of these runs are suitable for days of questionable stability.