Up to 40 cm of storm snow and extreme winds initiated a natural avalanche cycle on Sunday. As temperatures cool and winds diminish, we expect natural avalanche activity to taper, but the possibility of human-triggered avalanches will remain likely.
A facet or facet/crust interface 40 to 80 cm down, formed in late January, has been the failure plane for several large avalanches in the region. We have limited information on its spatial distribution, but this layer has been observed on all aspects and elevations.
New snow, warm temperatures, and strong south and west winds have formed surface slabs at all elevations. In exposed terrain, this problem may present as wind slabs on lee slopes. Reports of touchy cornices were also noted on Sunday.
Local ski hills reported newly formed, widespread touchy storm slabs and wind slabs on Sunday. A combination of natural, skier-triggered, and explosive-triggered avalanches up to size 2 were observed. We suspect this natural avalanche cycle will begin to taper on Monday, but human-triggered avalanches will remain likely.
Upto 40cm of new snow has been redistributed by extreme SW winds, forming storm and windslabs at all elevations. The Jan 24 facet/crust layer is down 50-80 cm and producing variable moderate-hard sudden planar results with stability tests. The distribution of this layer is difficult to pin down, but it has been observed at all elevation bands. A thin temperature crust exists on the surface at lower elevations. The lower snowpack is generally strong.
A cool air mass will move into the forecast region behind a passing front. Light precipitation and intermittent cloud cover will continue early this week, with up to 10 cm of snow possible by Tuesday. Freezing levels will remain near valley bottom, with moderate westerly ridge winds and more precipitation expected later this week.
