High avalanche danger this weekend. Very conservative travel will be required during this stormy period.
Confidence
Moderate - Timing, track, or intensity of incoming weather system is uncertain
Weather Forecast
Light snow should continue this evening bringing 5-8 cm above 1000 metres and moderate southwest winds in the alpine. Heavy precipitation driven by strong southerly winds should arrive during the night and result in 15-25 cm of new snow above 1200 metres. The storm should continue during the day Saturday and result in another 20-30 cm by Sunday morning. Freezing levels are forecast to rise sharply Sunday night to 2000 metres as the wet storm continues. Repeat for Monday!
Avalanche Summary
Widespread natural avalanche activity occurred during the Thursday storm. Areas that did not slide continue to be suspect. New storm slabs are expected to develop on Saturday.
Snowpack Summary
Deep storm slabs have developed in the alpine and at treeline above old wind crusts, melt-freeze crusts, and weak facetted crystals in some areas. Shallow facetted areas at treeline may now be buried by 70-100 cm of wind transported new snow. Cooler temperatures have re-frozen the moist or wet snow at lower elevations into a solid base layer.
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.