Regions
Northwest Inland.
Shifting winds are likely forming wind slabs in unusual locations.
Confidence
Poor - Due to the number of field observations
Weather Forecast
Synopsis: Arctic air to dominate for a few days, then warming from the north. Outflow winds should reach their peak Monday night. By Tuesday afternoon warmer Pacific air associated with the offshore upper ridge should move inland opening the door to a potential inversion or an above freezing layer between 1500 & 2500m.Tuesday: Freezing Level: Valley Bottom; Precipitation: Nil; Wind: Treeline: Light, NE | Ridgetop: Strong, NE.Wednesday: Freezing Level: Valley Bottom, potential AFL 1500 2500m; Precipitation: Nil; Wind: Treeline: Light, Variable | Ridgetop: Strong, N.Thursday: Freezing Level: Valley Bottom, potential AFL 1500 1500m; Precipitation: nil; Wind: Treeline: Light, Variable | Ridgetop: Moderate, NW
Avalanche Summary
A naturally-triggered size 2 slab was observed on Saturday on an alpine NE aspect in steep, windloaded terrain. A naturally-triggered size 1.5 wind slab was also observed at treeline on a north aspect in the Hankin area, which probably failed on Wednesday or Thursday. On Tuesday we received a report of a size 1.5 skier remotely triggered avalanche in the far north of the region. It released on a steep, wind loaded feature and was triggered from 5m away. The 25-45 cm thick slab occurred around 1600 m elevation.
Snowpack Summary
10-20 cm of new snow from Friday night is likely being formed into fresh wind slabs on lee slopes as winds shift into an outflow pattern. Older wind slabs from previous westerly winds are buried underneath. A layer of buried surface hoar down about 30-50 cm appears to be spotty in distribution, but may still be a concern in some areas. Near the base of the snowpack, the mid-November crust-facet layer has become less likely to trigger, but is still in the back of our minds.
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.