Slow accumulation of snow combined with winds continue to slowly build wind slabs in alpine lee features. A skier's weight could be all that it takes to trigger an avalanche.
Confidence
High - Due to the number of field observations on Tuesday
Weather Forecast
On tuesday the ridgetop highs will be -4, mainly cloudy with only a trace of new snow. The winds will be westerly at 50 km/h increasing to extreme in afternoon and evening topping out at over 100km/hr. Wednesday will be similar, with diminishing but continued high to extreme westerly winds.
Avalanche Summary
A few small loose dry avalanches were noted out of steep unskiable terrain near ridgetop on Easterly aspects.
Snowpack Summary
A 20-40cm wind slab is prominent on lee and cross loaded slopes at alpine and treeline elevations consisting of several laminated layers within the top 30cm, easy sudden planer snowpack test results were found on these interfaces. The January 6th layer was found down 50 cm but was not reactive at this site to testing. At treeline and below treeline up to 2050m a buried temperature crusts exists on all aspects. Below Treeline the snowpack is showing signs of continued faceting and weakening which is obvious when you step off of of the up track.
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.