19-20

1. Massive rolling collapse on lower ridge of ascent on Big Horn Peak. Felt like it went out hundreds of yards uphill. No avy activity. Other various collapses while skinning up ridge. 2+ weeks ago the lower ridge only had about 40-50 cms on it, so was not surprised to have that happen after large amounts of loading.

2. Specimen Creek: Heard several whumpfs and saw shooting cracks. No avalanche triggered, but a very unstable snowpack. Some whumpfs traveled farther than others. Very deep snow, fell to about knee height on parts of the trail, even in snowshoes...many shooting cracks and loud, traveling whumpfs as well as shaking ground from settling snow. This was relatively far from avalanche terrain on flat ground. Snowpack very unstable.

We encountered a natural avalanche that appears to have been triggered by a cornice drop. There seemed to be very little fresh snow on the slide surface so we suspect it occurred recently (Feb 14?). The slide occurred on the west side (east facing side) of Bear Basin (pinpoint on the map below). The avalanche was probably 200 feet wide at the top so it clearly propagate across the slope. Crown was 2 to 5 feet tall. We did not hike in there to investigate more carefully. There is a fair amount of trees on this part of the ridge. The picture shows how some large chunks got hung up on trees but we could see that the slide ran across the creek below (almost 1000 vertical feet). We had planned on skiing this slope and/or the open meadow (talus field) a hundred yards north but in light of this observation we turned around, skied back down in Middle Basin in the trees. Side note: we dug a pit earlier on an almost identical aspect (on the Beehive/Middle basin ridge) and obtained ECTN 16 @ 12" below the surface, ECTN 23 @4" below that, ECTN 28 @ 6" below that... Basically some definition between the latest storm layers but no propagation, and a right-side up snow pack. We only dug about 3 feet deep so this pit did not assess the ground level facets, which we figure are wide spread. The natural slide we encountered one ridge over seemed to be a case where a thin area was triggered by a cornice drop.

1. Observed a sizable deep slab in the Divide basin which appeared to have run within the last few days. The crown extended from the southern end of the basin (northeast facing) through the summit run off Divide (southeast facing)--maybe around a mile. Slab height varied, with the upper end pushing 10 feet and the lower closer to a foot or two. On Divide, the crown approached the summit and debris had run across the flat to the mature trees. Looked like it may have been cornice triggered at the southern end on thinner cover in rocky terrain.

2. Skied the NE shoulder of Divide Peak. Spotted a 1/4 to 1/2 mile long crown spotted along the NE face of Peak 10,024, between Divide Peak and Hyalite Peak. We could not directly determine the crown height, but it was highly visible from our location ~1 mile away.

3. Several large avalanches along the west ridge of divide basin. Appeared to be set off by large cornice drops that propagated across the bowls and stepped down several feet into the snowpack.