Front Range
Snowpackmarkus beck · Feb 11, 2012 · Front Range
Weather
Morning mostly clear with moderate radiation (several small wet loose observed on steep SE-S), becoming mostly cloudy with intermittend very light snowfall. Tmin -10C, Tmax -5C. Ridgetop winds moderate from W, lower down light variable.
Snowpack
Overall very weak on all eleveations, especially NW-E-SW. Stability ratings: BLT fair TL poor ATL fair. BLT the snowpack mostly consists of facets, though in open glades, more cohesive snow is more prone to fracture and propagation; such slopes of 35+ are suspect. TL the snowpack appears most reactive: Several far (up to 200ft with visible cracks!) rumbling collapses, and repeatedly weak stability tests. Slopes approaching 35+ are suspect. ATL there are widespread HS atop a weak snowpack that seem hard to trigger but would propagate more readily; most likely trigger points are areas with shallow snowpack, or large loads such as snowmobiles. Many of the old and recent avalanches have refilled- the basal DH is still present - and look ready to be triggered again. Instabilities (several test profiles on NE-SE TL and ATL, on 23-37dgr): 1) Storm slab: density inversion ~12cm down producing CT M/H Q1-2, also observed as failure layer in minor cracking. 2) Storm and Wind slab: 4F to F (new snow, df) atop 1F to P (1mm facets or crust with facets) 30-40cm down producing CT E/M Q1, ECT X, PST 40,100 (end, sp). 3) Persistent slab: failures upon isolation, PST 30,100 (end, sc) on large DH near ground. 4) Persistent slab: in isolated, specific areas near below TL, 0.5cm layer of surface hoar (3mm) resting atop 1F to P layer of facets down 40cm produced CT E/M Q1 and ECT M(P, sc). This is the first day in a while that the snowpack has been this reactive. Over the last few days, 20-30cm new snow has fallen in the area. Though low density and with not much wind, it seems this light additional load is starting to stress the very weak snowpack - with light but steady accumulation and increasing winds, skier triggered SS especially on NW-E-S and near TL are becoming more likely. The recent storm snow is making it difficult to detect cracking/collapsing as it muffles the sound and hides the cracks, and is covering many of the trigger points especially ATL (areas where the HS is softer and/or shallow, small undulations).