Natural avalanche activity has slowed down, but human triggered avalanches remain likely, especially in wind loaded areas and at lower elevations where a buried surface hoar layer has produced avalanches recently.
Weather Forecast
MONDAY NIGHT - Clear periods / northwest winds 10-15 km/h / alpine low temperature near -17TUESDAY - A mix of sun and cloud / northeast winds 10-15 km/h / alpine high temperature near -15WEDNESDAY - Mainly sunny / northwest winds 15-25 km/h / alpine high temperature near -15THURSDAY - Cloudy with flurries, 5 cm / southwest winds, 15-35 km/h / alpine high temperature near -13
Avalanche Summary
Natural avalanche activity slowed to some degree on Sunday. Several natural avalanches to size 2.5 were reported. Human triggered avalanches to size 2.5 were also reported, many of these were triggered remotely (from a distance). Most of these failed on a persistent weak layer that was buried in mid January.Widespread avalanche activity was reported on Friday and Saturday. Numerous natural and explosives triggered avalanches to size 3.5, and human triggered avalanches to size 2 were reported. Many of these avalanches were triggered remotely (from a distance) and failed on the mid January layer.Human triggered avalanches failing on the mid January persistent weak layer have been reported almost daily for the past two weeks in the North Columbia region.
Snowpack Summary
30-80 cm of recent new snow sits on surface hoar (feathery crystals), facets (sugary snow), wind slabs and a crust on sun-exposed slopes. In many areas, recent winds have redistributed the new snow, forming wind slabs on all aspects due to shifting wind directions.A persistent weak layer that was buried in mid January is now buried 50-100 cm. This layer consists primarily of surface hoar, however there is also a crust associated with it on sun-exposed slopes. This layer has been most reactive at treeline and below, and was very reactive during the height of the recent storm.
Problems
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.
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.