A stiff, persistent slab sitting over weak layers will continue to plague the back-country for the foreseeable future. The greatest concern is at, and just above, treeline however these slabs are represented at all elevations and on all aspects.
Weather Forecast
Cold arctic air dominating the region. Alpine high forecasted to be -22 for Wednesday with broken skies and light north winds. Brrr!
Snowpack Summary
15cm snow over the last week, and available snow from the previous storms, has been redistributed by strong winds from variable directions to build slabs and wind effect in open areas. A persistent slab sitting on three weak layers down 50 to 80cm can be found throughout the forecast region and has produced many large avalanches traveling full path
Avalanche Summary
No new avalanche activity observed or reported in the last week however an extensive cycle resulted when the persistent slab became overloaded with successive storms totalling 50cm each on January 30th and February 8th. Avalanches to size 3.5 were observed from most aspects and at most elevations with the majority of the action seen around 21-2500m
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.