The last time we saw loading from new snow in the Sierra was on January 27th when northerly winds redistributed cold snow from the previous storm. Since then, another ridge of high pressure has settled over the west coast and well-above average temperatures have been the new normal. Clear skies and below freezing temperatures overnight have allowed the snowpack to get a good re-freeze in most areas. But as the sun again heats E to S to W facing slopes today, with few clouds impeding the incoming radiation, the thawing process will begin all over again. Even lower elevation northerly slopes have developed melt-freeze crusts where vegetation has helped hold in the heat. A few small loose wet avalanches have been reported on steep Southeasterly slopes. All of this has occurred despite the relatively low angle of the February sun. That low sun angle means snow surface warming will be less than we would expect to see in April or May. And our thin to non-existent snowpack on the slopes receiving the most warming will further isolate the avalanche problem. That doesn’t mean that loose wet avalanches will be impossible as the snow becomes deeply saturated with melt water by late morning. Even small and slow-moving loose wet avalanches can be dangerous in or above terrain traps like cliffs or extreme terrain. They could knock you off your feet and take you somewhere you don’t want to be. Avoiding slopes that are warm enough for large rollerballs or to sink in past your boot tops is the best way to keep yourself out of trouble.
Early in the day, before the snow softens, icy conditions will be a hazard. Crampons could help reduce your exposure in steep terrain where falling could result in a slide for life. The thin snowpack also means barely covered obstacles like rocks and logs will become more and more a problem as slopes melt out. Hidden obstacles resulted in a broken clavicle for one skier in the Negatives recently.
On northerly slopes, sugary facet snow still exists in layers throughout the snowpack. These layers are inherently weak and are worth monitoring even though an avalanche failing on them is unlikely. If we do ever get a good dump this season these weaker layers will suddenly become very concerning.