Grand Mesa
AvalancheDylan Craaybeek · Mar 15, 2022 · Grand Mesa
Weather
It was a warm and sunny day on the Grand Mesa. 40F Clear and Calm at the parking lot at 10:00AM. Some clouds could be seen looking east from the chairlift but no clouds overhead until around 12:00PM when the sky coverage remained Few for the rest of the day. Light westerly winds with occasional Moderate gusts at the ridgeline of the Grand Mesa and light snow transport above 9,700 feet. 48F, cloud coverage was Few, and Calm wind back at the base area at 5:00PM.
Snowpack
The average height of snow (HS) ranged from around 80cm on southerly slopes to 150cm on wind-loaded northerly slopes. The northern half of the compass has a reactive persistent weak layer that developed during the January-February dry spell. On west-facing slopes this weak layer is buried 20-40cm below the snow surface under a slab ranging from F hard to P hard on the hand hardness scale and two melt-freeze crusts (MFcr) rest within the slab. The facet layer is composed of faceted grains that are mostly rounded, well-bonded, 1 to 2mm in size, and 4F hard. Snowpack tests and collapses on these slopes confirm that this weak layer is still reactive (ECTP 20, ECTP7, ECTP14, ECTP15, ECTP21, one large [100+ foot] collapse). Northwest, north, and northeast-facing slopes have a 40-80cm slab with one prominent MFcr in the middle of it from the early March warm period. This slab rests on top of well-developed, large (2 to 4mm), striated facets. The facet layer ranges from 5-15cm thick. Below the facet layer of concern lies 40-80cm of 1F to P hard rounding faceted particles and 4F hard depth hoar (DH) at the base of the snowpack. Snowpack tests indicate and several slope-scale collapses as well as a recent avalanche all failed on the dry spell facet layer (ECTP25, ECTP22, ECTP24, ECTP19, 4 large collapses, one avalanche from within the past 7 days). East-facing slopes were similar to other northerly slopes but with a thicker MFcr within the slab and less-developed faceted layer showing similar results in snowpack tests. No collapses were experienced on east-facing slopes. Southerly slopes were shallow with water percolating to the early March MFcr with dry, unreactive rounding faceted particles below that crust. The surface snow was Saturated by 2:00 PM on southerly slopes.
Avalanche
Several Loose Wet avalanches were triggered on east-aspects. One old D2 hard slab avalanche was observed on a northeast-facing slope that failed on the dry spell facet layer within the past 7 days.