Northern San Juan
AvalancheColin Mitchell · Apr 10, 2018 · Northern San Juan
Weather
Beautiful spring day. Very warm temperatures and light winds. High clouds moved in over the course of my tour, and slowly thickened during the afternoon hours. Winds were strong enough to keep the snow surface relatively cool on all but due south aspects.
Snowpack
Overall, the snowpack stayed cooler than the weather would indicate. Not a lot of changes in the near and above treeline bands from last week. The snow has been hardened by wind, sun, and warm temperatures. Ski crampons mandatory even on relatively low-angle slopes. The surface slowly softened through the day. Isolated areas had several inches of D/F grains on the surface, but overall it was quite solid hardpack almost everywhere. The snowpack on south-facing slopes consisted of various layers of crusts and facets. HS from 0-125cm. The snowpack has seen water all the way to the ground in these areas. Mid-pack facet layers produced Q1 fractures with CTs, and propagating results with the ECT. Snow was supportable to skis and boots in the morning and early afternoon, but softening quickly with warm temps and sun. Fist-hard basal facets didn't produce with tests, likely due to the thickness of the layer and the high moisture content. See profile from Red 3 for details on structure. Northerly slopes were still quite wintry, although moist to the ground, indicating that the recent rains and warm temperatures are starting to have an effect. There is still a pronounced layer of fist-hard rounding depth hoar at the ground. ECT tests produced repeatable propagating results on this layer, 14 and 16 taps respectively. See MacMillan Peak profile for structure and test details.
Avalanche
No avalanche activity observed today