As rain falls today and dissolves the bonds between already wet snow grains loose wet avalanches are expected to be widespread and potentially large. Watch out for wet snow at the surface and boot-top penetration into slushy snow. Rollerballs or pinwheels are a good indication that the snow is losing cohesion. Loose wet avalanches will be the first problem to become likely today with a poor refreeze overnight and rain already falling. Wet snow on steep slopes is a combination to avoid today.
By this evening 4” or more of thick moist snow are expected above 11,000’. Winds will be strong enough out of the SW to redistribute it into dense wind slabs on leeward alpine slopes. Winds can deposit snow at 3 to 5 times the rate it can fall from the sky, so some of the new slabs could be large. Watch out for dense drifts below high elevation cornices and in the tops of steep chutes and gullies where crossloading may deposit slabs further down slope.
The snowpack this season remains complex. Areas at lower and middle elevations, and in the southern part of the forecast area, seem to have transitioned to a moist spring-like regime. But above 10,000’ on northerly slopes, especially in the northern half of the region, the snow is still cold enough to be wintry. These colder and deeper snow will absorb and hold more of the rain and become saturated. This could further weaken any poorly bonded layers in the snowpack and create a wet slab problem. Today this problem will be less likely, but the problem will become more touchy and more possible as we receive more moisture. Steep northerly slopes in the middle and upper elevations may become the starting zone for very large wet slab avalanches by tonight. Especially if a smaller loose wet or wind slab avalanche suddenly overloads one of the weak layers buried in the colder, drier snowpack.