Spring has returned to the Sierra after another fast moving storm swept though on Tuesday and between 3 and 12 inches of new snow fell across the forecast area above 8500’. Snow levels fluctuated during the storm and many areas received rain Monday before snow in the early morning hours on Tuesday. Rain fell again up to almost 9,000’ Tuesday morning before a final shot of snow by Tuesday afternoon. Loose wet avalanches were prevalent during the storm at middle elevations. Temperatures were colder at higher elevations and the strong southwest winds accompanying the storm redistributed new snow onto leeward slopes above about 9,000’. Mammoth Mountain Ski Patrol reported large results from avalanche control work on Wednesday morning. Most of these avalanches were triggered in wind slabs with small hand charges and ski cutting.
Winds continued to blow from the west on Wednesday and Thursday and there was enough soft snow still available for transport that snow banners and localized drifting were seen from Mammoth south to Rock Creek. Snowpack observations in Rock Creek showed that some of these wind slabs were slowly healing, but also that the snow at higher elevations is still soft and cold. Near Bishop things were already warming up yesterday. But in other areas, today may be the first time this dry snow becomes wet which will increase the possibility of loose wet avalanches. Rocky outcrops, gullies, and trees will trap the sun’s heat today and reflect in back down onto the snow, also elevating the hazard of wet sloughing. Large pinwheels or ski penetration of boot top or greater are signs the snow is loosing strength and becoming unstable. Starting early and being out of steep, rocky terrain before things get too warm is the best strategy for avoiding loose wet avalanches.
Early in the day, firm, slide-for-life conditions may exist. Be careful of your exposure to a slip and fall on steep terrain where consequences are high.