Out Gold Creek Trail and into upper drainage. Remained below tree line.
Feb. 26, 2018, noon PST
Weather: Broken clouds/sun. Low elevation temps were in the lower 30’s and winds were light out of the SW. Upper elevations mostly remained under cloud cover. Sun was feeling strong.
Snowpack: Up to 2ft of new snow at lower elevations. Supportable, and mostly right side up with some lighter density snow and recrystalized grains capping things off. Test pits at mid elevations revealed good strength, fair structure. A few moderate compression results in the upper snowpack did not indicate energy for propagation. Facets at the 2/13 interface were well over 3ft deep in undesturbed snow, they were unreactive and appeared to be sintering. By 4pm solar slopes had picked up a sun crust while shaded slopes remained light and dry. No cracking or collapsing was observed.
Area Description: Upper Gold Creek / Lower NW flanks of Alta Mt
Avalanches: Several large (R3-D3) avalanches were observed to have run down the W and NW flanks of Alta Mountain, in several places almost depositing into Gold Creek. In places debris from these slides was drifted over or buried by less than 1ft of new snow, indicating they probably ran during height of sensitivity Sunday. Also of note was more recent and relatively widespread loose activity. While there was recent evidence of both dry and wet surface sloughing on most aspects, the bulk of activity was concentrated on solar slopes. In particular the SE face of Alaska Peak was very active with roller balling and widespread wet loose activity. Also, several smaller wind loaded or leftover storm slab pockets were observed to have propagated from this activity. Storm slabs were not observed anywhere below treeling despite their forecasted widespread distribution. While it is possible the larger avalanches failed on a deeper persistent weak layer, the debris was more indicative of a widespread natural cycle of storm snow. It appears that any issue with a PWL will most likely not be found below treeline and from the weekend’s obs, is probably more isolated to upper elevation, moderately angles slopes on N 1/2 aspects, where shaded slopes and cold temps have allowed these grains to persist. Furthermore, if this weekends extensive loading was any test, most upper elevation slopes have appeared to have passed. I might not be stepping out, but test pits, a decreasing temperature gradient, and increasing height of snow all point to this problem moderating on many aspects and elevations. Today was a good reminder to begin to be considerate of solar effect between storms, it might not be in the forecast but it’s easy to forget it’s just about March and the sun is strong, I’d certainly add wet loose activity to my list of hazards moving forward, especially if you’re considering that any surface activity has the ability to step down into deeper layers.
Observation by Shag Nasty
Did you see any avalanches? Yes
Did you trigger any avalanches? No
Was anyone caught in an Avalanche? No