The likelihood of triggering a persistent slab has reduced, however the consequence of doing so would be significant.
Weather Forecast
THURSDAY Night: Mainly cloudy with isolated flurries, light to moderate southeast wind, alpine temperature -10 C.FRIDAY: Scattered flurries, accumulation 5 cm , light to moderate southwest wind, alpine temperature -8 CSATURDAY: Mainly cloudy with isolated flurries, light north wind, alpine temperature -12 CSUNDAY: Mix of sun and cloud, light to moderate northeast wind, alpine temperature -15 C
Avalanche Summary
On Wednesday there was a report of a skier triggered size 1.5 wind slab avalanche on a north east aspect at 2200 m. On Tuesday there was report of a skier triggered size 2 persistent slab avalanche 60 cm deep on an east aspect at 1900m. On Sunday there was a small human-triggered avalanche was reported from a north aspect at 2100 m. It failed around 35 cm deep on the mid-January surface hoar layer.
Snowpack Summary
A touchy weak layer responsible for a several close calls and surprise avalanches lies approximately 50 cm below the surface (30 cm in shallow areas, 60 cm or more in deeper spots). This weak layer was buried mid-January and comprises a mix of surface hoar and facets. On southerly aspects, it lies on top of a sun crust. It is shallow enough to be easily triggered but deep enough to produce large avalanches. It is most prevalent at treeline and below, but there have been a few reports of its presence in sheltered areas in the alpine.Average snow depths are approximately 270 cm. Lower layers in the snowpack are not a significant factor at this time.
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.