Storm snow continuing to accumulate will stress buried weak layers. Expect human triggered avalanches to be likely.
A couple of weak layers formed in late November and early December are now sitting about 1 m plus below the surface. This layer may present as surface hoar, a crust, facets or a combination of those, depending on elevation and aspec.
Snow accumulating above a buried layer of weak surface hoar has created a touchy storm slab problem. The conditions are primed for human triggered avalanches.
TUESDAY NIGHT: Snow, accumulation 5-15 cm, moderate to strong southwest wind, alpine high temperature -6 C.
WEDNESDAY: Flurries, accumulation 5 cm, moderate south wind, alpine high temperature -4 C.
THURSDAY: Scattered flurries, moderate southwest winds, alpine high temperature -7 C.
FRIDAY: Flurries, accumulation 5-10 cm, moderate to strong southwest wind, alpine high temperature -3 C.
There was likely a natural avalanche cycle on Tuesday.
On Monday there were reports of both wind and storm slab avalanches to size 1.5 on northerly aspects at treeline and in the alpine.
On Saturday there were 3 reports of skier triggered persistent and storm slab avalanches running on surface hoar buried 25-50 cm deep. These ranged from size 1 to 2 and were on north, west and south aspects between 1400 and 2000m. Two of these were remotely triggered (from a distance). There was also a report of a snowmobile triggered size 2 persistent slab avalanche on an east aspect at 2300m
40-70 cm of recent snow has accumulated above a widespread layer of large, feathery surface hoar crystals. New snow is expected to continue to accumulate and consolidate above this layer over the next few days, maintaining a high likelihood of human-triggering.
A weak layer formed in late November is now buried around 1 m plus below the surface. This is the layer of concern relating to the persistent slab avalanche problem. The weak layer may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect. Below this, a variety of crusts from late October are buried deeper in the snowpack.
