We saw another avalanche cycle today involving the new wind slabs in the alpine. Both weak layers mentioned in the bulletin were involved. Rapid heating may become a trigger, especially in thin rocky areas.
Weather Forecast
High pressure is here. No new snow for the next few days, just sun. The temps are expected to rise to above zero in valley bottoms and hover just below zero in the treeline range. Winds will stay at the moderate level with the occasional bump to strong.
Avalanche Summary
A widespread Na cycle started today involving the new storm slabs. Slides up to 2.5 were noted throughout the forecast area. They all initiated in the alpine with a variety of layers suspected as the sliding layer. A sun triggered sz2 pulled out on Rundle with the Oct temp crust being the culprit. Storm snow/existing wind slab interfaces are suspected in the others. The avalanches were in moderately angled terrain (35-45 degrees) and tended to be in more open areas. N-SE aspects.
Snowpack Summary
Wind slabs created with the readily available storm snow continue to develop (and shed) in the alpine. A fairly widespread cycle was observed today with lots of activity in the alpine. Most alpine features had evidence of slab avalanches from the last 12 hours. At TL & below the snowpack is still weak with difficult trail breaking up to TL. The ongoing crust problem is still there and a real concern in thinner areas.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.