Regions
Northwest Inland.
Now that the storm is over, signs of avalanche danger may be less obvious. Touchy wind slabs are lingering.
Confidence
Poor - Due to the number of field observations
Weather Forecast
A brief clearing is expected on Tuesday, before a Pacific frontal system pushes ashore late that day. Generally light precipitation is expected on Wednesday and Thursday, with the freezing level around 1000 m and winds moderate from the S to SW. The next punch of moisture arrives on Thursday night.
Avalanche Summary
A large and widespread natural avalanche cycle occurred last week and into Saturday. On Sunday, skiers triggered several size 1 storm slabs on steep lee features. Click on the blue dot on the map to see a recent wind slab that may have failed naturally or remotely in Sinclair. It was a thick, hard wind slab on a north aspect. There are likely to more like this lurking.
Snowpack Summary
Anywhere from 20 to 120 cm recent storm snow has been redistributed by winds into soft and hard wind slabs at alpine and treeline elevations (highest storm snow amounts were in the north and west). This overlies various surfaces including old wind slabs, hard crusts, surface hoar, and/or surface facets. At the base of the snowpack, weak facets may be found. Cornices are large and potentially fragile. Below treeline, the snow appears to be in a spring melt-freeze cycle.
Problems
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.