Fast moving spring showers, dropping between 1 and 12+ inches of snow, have been affecting our area for the past week. These storms have come with moderate to strong southwest winds that transport much of that new snow onto leeward slopes and pack it into dense wind slabs. In the hours and days between, warm temperatures and sunshine have been returning to heat the new snow and cause wet point releases near rocky areas and in steep terrain. One such cycle played out this past weekend. Wind slabs deposited during Friday’s storm released from artificial triggers throughout Saturday. Mammoth Mountain Ski Patrol had widespread results from avalanche control work and skier-cut cornice drops on the Mammoth Crest produced several large slides. Loose dry avalanches were also widespread Saturday morning in steep areas that had received the most new snow. But, temperatures warmed significantly Saturday afternoon, and, as is typical for spring, loose wet avalanches quickly became a problem at middle and lower elevations.
Sunday, moderate southwest winds began to blow again ushering in the next quick moving front across the Sierra. This latest storm has already left 1 to 3 inches of snow as of early Monday morning, primarily in the northern half of the forecast zone. This combination will create wind slabs on steep, middle and upper elevation slopes and features that promote drifting and loading. Showers will exit the region today (Monday) and we can expect winds to shift more to the north tonight and Tuesday when temperatures will rebound. With increased sunshine and higher temps this afternoon and Tuesday, loose wet avalanches will become increasing likely at lower and middle elevations. Large pinwheels or ski penetration of boot top or greater are signs the snow is loosing strength and becoming unstable. Pay attention as you travel, notice conditions changing and trends. Perform your own stability tests and identify potentially hazardous terrain.