Purcells

A new persistent weak layer has "woken-up" and warrants your attention, especially in the west/southwest parts of the region. Read the whole bulletin for details.

Moderate - Wind effect is extremely variable

Wednesday: Overcast skies with light flurries / Moderate to strong southwest winds / Alpine temperature of -12Thursday: Overcast skies with light flurries / Moderate southerly winds / Alpine temperature of -7Friday: Overcast skies with light flurries / Light and variable winds / Alpine temperature of -10

In general, recent avalanche activity has consisted of mainly wind slabs (skier triggered and skier remote) in the size 1-1.5 range. However, we've also received reports of several persistent slab avalanches to size 2 from the west and southwest parts of the region where recent accumulations have been the highest. These avalanches, which have been skier-triggered or remotely triggered (from a distance), have been failing primarily on a buried sun crust buried mid-February.Although deeper, persistent avalanche activity has become less frequent over the past week, light triggers in shallow rocky areas, as well as large triggers such as a cornice collapse or step down from a wind slab release still have the potential to result in large destructive avalanches.

Since Saturday night between 5 and 30 centimetres of snow fell with the greatest accumulations occurring in the southwestern corner of the region. Winds have shifted these accumulations into deeper, reactive slabs in wind-exposed terrain. Up to 60cm below the surface you may find an interface that was buried mid-February consisting of older wind slabs, a sun crust on steep solar aspects, and spotty surface hoar on sheltered slopes. Reports suggest this interface may be most reactive on solar aspects where the buried sun crust coexists with small facets. There are several persistent weak layers that have shown signs of improving but still remain suspect as low probability - high consequence avalanche problems. Two surface hoar layers buried in January are now 80-120 cm below the snow surface. Deeper in the snowpack (about 150 deep) is a facet/crust/surface hoar layer buried in December. Near the base of the snowpack is a crust/facet combo layer buried in late November. These layers may "wake-up" with strong inputs such as solar radiation, rapid loading/warming, or a cornice fall. Human triggering is also possible in shallow, rocky terrain.