The depth hoar layer is buried under 4-5 feet of snow in the Mammoth Basin except in some north to east facing gullies that avalanched in early February. Observations in Hammil Bowl yesterday were made in on slopes where last week’s avalanches occurred. Snow depths were shallow (2-3 feet) and the snow surface was firm hard wind affected snow. There was 8-12 inches of fist hardness depth hoar at the bottom. Extended column tests did not propagate cracks.
As spring approaches, these north facing slopes receive longer periods of direct sun and eventually the surface will melt. When liquid water reaches depth hoar and facets, there is a sudden loss of strength and wet slab avalanches may occur.
Temperatures remain cool today though solar radiation will melt the snow surface at mid-elevations in the trees. Chances are increasing for loose wet avalanche activity by Thursday.