Southern San Juan
SnowpackChris Bilbrey · Mar 17, 2021 · Southern San Juan
Weather
Mild day in the mountains with light northwest winds near and above treeline. Partly cloudy skies provided nice breaks from the sun and warmth.
Snowpack
The upper snowpack is quickly transitioning since our last major loading event came to an end Sunday night. The 4 to 8 inches of new snow over the past couple days has not created new problems or changed to the overall avalanche danger. Rapid settlement in the storm snow was most pronounced on southerly facing slopes at all elevations. In our travels today, we targeted sensitivity of buried weak layers below recent snowfall on northeast through east to south-facing slopes near and above treeline. We observed non-propagating results in faceted grains and below a facet/ crust combo on east and southeast aspects. No other signs of instability observed in this area on our travels. Southerly-facing slopes above treeline had a Pencil to 1F hard wind-drifted slab sitting above 4F decomposing fragments that failed with 11 taps in consecutive Extended Column Test. This same slab was unreactive to ski pressure and quickly dissipated once we got further away from ridge tops. Snow surfaces got moist today on all aspects below 12,000 feet but remained dry above that. Later in the day, any slope that saw direct sunlight formed a thin zipper but breakable crust. We found evidence of water percolation/ pooling around 70 cm's below the surface. An ice mass was visible and still frozen at that depth. Moist depth hoar grains were the weakest on an east-facing slope and will be something to monitor during periods of non-freezing nighttime temperatures as the threat of Wet Slab avalanches loom in the future.