Heavy rain Friday and through the night has saturated an already loose wet snowpack. Widespread, potentially large, Loose Wet avalanches are expected today up to ~11000’, possibly higher. These may erode deep into the snowpack. Deep ski or boot penetration, rollerballs, and pinwheels are signs of loose saturated unstable snow. Loose Wet avalanches will be most wide spread avalanche problem for Saturday.
Snow overnight above ~11,000’ and strong SW winds have likely produced thick moist , Wind Slabs on NW-NE-SE aspects, some of these slabs could be large. Anticipate dense drifts under ridgetop cornices, tops of steep chutes, and sidewalls of gullies. As temperatures begin to cool this afternoon, Wind Slabs may begin to form down to ~9000’ in open and exposed terrain.
The snowpack is transitioning to a spring regime. South of Mammoth, the lower and middle elevation snowpack has mostly transitioned to a dense spring snowpack. North of Mammoth, on northerly aspects above ~10,000’, the snow is still cold and dry below the surface snow. The snowpack depth and colder nature can absorb more water and become saturated, weakening bonds between snow grains and adjacent layers and increasing the threat of Wet Slab avalanches, especially middle and upper elevations where Loose Wet or Wind Slabs avalanche could trigger a large avalanche.