Winds slabs in exposed terrain are the main concern. Watch for whumpfing, cracking and natural avalanches.
As wind picks up over the weekend there is potential for new wind slabs in lee terrain features. These wind slabs may be sitting on top of weak surface hoar crystals, which would make them more easy to trigger.
There is a spotty surface hoar layer 30-65 cm deep that appears to be unreactive in most areas, however, there have been some isolated whumpfs on this layer around Pine Pass. With such an isolated distribution, triggering an avalanche on this layer is unlikely, but the potential size means some extra caution should be taken with steep open slopes.
SATURDAY Night: Mainly cloudy, moderate southwest wind, treeline temperatures around -11 C.
SUNDAY: Cloudy with flurries and accumulation 2-3 cm, moderate southwest wind, treeline temperatures around -8 C.
MONDAY: Scattered flurries with 5-10 cm of snow, light to moderate west wind, treeline temperatures around -12 C.
TUESDAY: Cloudy with flurries, moderate southwest wind, treeline temperatures around -11 C.
No avalanches have been reported in the past week, however some notable shooting cracks and whumpfs were reported around Pine Pass on Thursday. They were both linked to buried surface hoar layers, one 30 cm deep underneath a fresh wind slab (here) and the other 65 cm deep underneath old snow (here).
Wind slabs developing above surface hoar is a good example of the primary problem we expect to see over the weekend. The deeper surface hoar layer appears to be a very isolated problem on specific slopes in the north of the region.
Open terrain is likely being impacted by moderate wind, with wind slabs forming on lee terrain features. Sheltered areas have 10-20 cm of soft faceted snow. Underneath the soft snow and new wind slabs, you will likely find a hard melt-freeze crust up to roughly 1600 m, perhaps weak and feathery surface hoar crystals, and otherwise wind packed snow. Wind slabs developing above surface hoar could be particularly reactive.
There is a spotty weak layer of surface hoar 30 to 65 cm deep in sheltered treeline terrain. This layer has not produced any avalanches to date, but our field team reported some large whumpfs on this layer at Pine Pass on Thursday.
There are presently no deeper concerns in the snowpack.
