Quick report
- Collapsing
- isolated
We went to Powderhouse Peak to look at the near surface facet layer that was buried under recent new snow starting Feb 10. This weak layer, formed during the January dry spell and exists on many northerly aspects within the forecast area. On Powderhouse Pk, as in other locations, this weak layer was capped by a rain crust up to about 8,600'. Above 8,600' there was 10 to 12 inches of recent storm snow on top of the facet layer with no rain crust present. We dug a snowpit at 9,100' on a N aspect (see snowpack section below). We found a developing slab on top of the Feb 10 weak layer that was getting close to reactive but not quite there yet (too brittle). It seems very likely that additional new snow load containing 1-2+ inches of SWE will bring this layer to the point of collapsing and contributing to avalanches.
We noted isolated areas of surface hoar both at the very bottom (meadow) and on the summit ridgetop of Powderhouse Peak.
We triggered a single, very small area collapse of a wind pillow over the Feb 10 facet layer. The pit was dug in the immediate vicinity, about 10 feet downslope of the collapse trigger point.Weather
- Air Temp
- 33
- Cloud Cover
- clear
- Wind Loading
- none
- Recent Snowfall
- 29
- Snow Avail For Transport
- moderate amounts
Calm conditions on the ridgetop.
Snowpack
A slab is beginning to form on top of the Feb 10 facet layer as the recent storm snow settles and gains strength. The CT showed a sudden collapse result. The ECT and PST indicated that propagation along the weak layer remains unlikely as the slab is still too brittle. Significant new snow loading (expected Monday through Wednesday) is expected to change the slab properties and bring this weak layer to the point of propagating failure.