Central Sierra Nevada

Easly season conditions update #2.

We are still without sufficient snowcover to warrant daily avalanche advisories. We are making snowpack observations and posting them to the observations page.

The handful of field observations we have made over the past week have revealed areas of continuous snow cover limited to upper elevation NW-N-NE aspects. This is generally above 8,000' along the Sierra Crest and above 9,000' in the Mount Rose area. Snowfall leftover from the October 28 storm event provided the existing snow cover in these areas. The widespread trend in snowpack structure observed thus far on mid and upper elevation NW-N-NE aspects is fairly thin and weak melt-freeze crust on top of facets down to ground level. Overall snowpack height ranges from 6 to 12 inches deep in the areas that have continuous snow cover. Most other aspects melted out since late October, exposing bare ground in the majority of areas. An inch or two of snow fell this morning, adding little to the existing snowpack. Check out the Observations Page for additional details.

If the upper end of forecast snowfall amounts are reached over the next 36 hours, up to 1.5 feet over new snow would accumulate above 8,000'. With little to no wind forecast during the snowfall periods, wind loading and subsequent wind slab formation will be minimal to nonexistent. The weight of the additional snowfall may have some effect of stressing the basal facet layer, but this layer is well anchored by rocks and scree in most areas. A few of the upper elevation NW-N-NE aspects hold enough snow cover to negate any effects of anchoring for the new snow that is expected to deposit on top of the surface crust and basal facet layer over the next 36 hours. With little to no wind forecast, any instability that forms within the expected high density new snow will likely be limited in distribution and size.

With the track record of the weather models over the past several weeks, it will be interesting to see how this storm cycle plays out. If you head into the backcountry, keep an eye out for recent avalanche activity. Other signs of snowpack instability including wind loading, collapse, audible whumpfing sounds, shooting cracks, and/or test slope failure are indications that the snowpack in the immediate area is unstable.