Gunnison
AvalancheEric Murrow & Ben Pritchett · Dec 30, 2018 · Gunnison
Weather
Did not take air temperatures, but temp warmed with elevation, cold near valley bottom. Clouds built throughout the day in front of approaching storm system.
Snowpack
Starting at ridge top at 11,100 ft - forested areas were still holding on to a 1-finger mid-pack resting upon weak basal facets. Snow surface was weak, but just enough stiffness in the mid-pack to travel assuming it's possible to trigger a slab on a steep slope. Areas just below the ridge top that previously avalanched this season were weak and very faceted. We could trigger numerous facet sluffs in steep terrain that ran down to the Dec 19th interface. On slopes that avalanched previously with a weaker structure (missing mid-pack) the sluffing entrained to near the ground. Height of snow maxed out at about 100cm. Descending down to 10,600 the midpack lost strength to 4-finger in open areas. Snow surfaces remained weak with newly formed surface hoar on top in open areas. While inspecting a suspected skier trigger slide from earlier in the week (Dec 27th). A skier had triggered a 20-30cm deep Fist-hard slab that released on a layer of buried surface hoar (December19 interface). The slab that broke in the avalanche on Feb 27th was now too faceted to propagate. Ski cuts, CT and ECT tests produced no results in the crown of that recent avalanche. We did however trigger small loose avalanches in the same snow that failed as a slab 3 days prior. As we descended further to below 10,000' the effect of the Gothic (East River) Valley's cold sink was apparent. It felt much colder today as we approached Gothic Road, and the snowpack showed the impact of that temperature trend recently. The snowpack was weaker still and became Fist-hard top to bottom, with easy to trigger sluff's on steep slopes. Overall the snowpack on this shaded north to east facing terrain was weak with little strength throughout. Surfaces are weak and will not support much load, and any avalanche will entrain all snow down the December 19th interface or deeper. Wouldn't be surprised to see some small natural activity Monday afternoon if the storm produces even as little as 0.5" of SWE.
Avalanche
We inspected a suspected skier triggered slab from earlier in the week (observed Thursday 12/27). This slide failed on surface hoar, likely 12/19. There was no slab structure left and produced facet slough immediately adjacent when we descended. At valley bottom two another avalanches were visible near ridge top on open terrain. Likely failed on same interfaces as the one we inspected.