Quick report
We experienced one very small and localized collapse when we regrouped on sleds in the flats on a low elevation slope. This may have just involved some sort of void in some sagebrush/rocks below.
Weather
- Cloud Cover
- clear
Clear skies with occasional pods of cumulus visible on the western horizon. Winds were generally calm to light, but occasionally gusting to the upper end of light/low end of moderate speeds out of the W.
Snowpack
On wind-sheltered slopes the snow warmed enough to produce a minor surficial wet loose problem. All natural slides we observed were releasing in the upper few inches of the snowpack. A hard freeze overnight is likely to prevent any slow-burn wet issues here.
We observed generally weak snow surfaces that will provide poor bonding surfaces when precipitation returns on Sunday night. We found a fresh crop of surface hoar that extended all the way to our highpoint at 10,700'. The sun was wilting this on solar aspects and the wind had blown some over, but we may see this weak layer survive through the weekend and become buried on shaded, sheltered slopes.
HS at the mouth of the drainage is around 60-70cm, increasing to 110-120cm by the summer TH at the back of the drainage. We dug between 9,400 and 9,600' on sheltered shady and solar slopes where HS was 130+ cm.
-The 2/14 interface is down 20-25cm here and presented as a non-descript crust on solars and weakly developed facets on shaded slopes.
-The 2/1 interface (which has been our main upper snowpack layer of concern) is buried down 40cm and presents as a rain crust (IFrc+FC) on shaded slopes (though the water-ice lens was thinning and becoming less obvious where we dug at 9,400') and a sun-cooked aerated MFcr with FC on solars. If you find the right combination of slab+weak layer you can definitely make an avalanche on the 2/1, but given the specificity of this distribution this problem is secondary to the 1/6 described below.
-The 1/6 interface (our December drought snow) remains the primary layer of concern here. This layer is widespread, but is armored by a very dense slab on top. On shaded slopes, the hardness difference between the overlying slab (P to P-) and the December drought snow (4F-) is dramatic. This layer is difficult to impact in column tests, even with significant force past standard loading steps. However, knowing how "well" this weak layer has performed and how broadly it was distributed points to this as the continued primary focus.
Avalanche
- Size
- D2
- Count
- 4
- Aspect
- S
- Trigger
- N
- Elevation
- 10600 ft
We observed a half dozen small wet loose slides that released naturally this afternoon. The largest produced debris piles that were 20-30 feet wide and about a foot or two deep. We observed a number of large to very large, older avalanches.