Regions
Northwest Inland.
Previous snow and wind has formed wind slabs at upper elevations that may be sitting on a weak layer. These may be reactive to human triggers, especially in wind loaded areas.
Confidence
Moderate - Due to the number of field observations
Weather Forecast
MONDAY NIGHT - Clear periods / light southerly winds / alpine low temperature near -1 / possible alpine temperature inversion TUESDAY - Mainly cloudy with flurries beginning in the afternoon / southwest winds 10-30 km/h / alpine high temperature near +1 / possible alpine temperature inversionWEDNESDAY - Mainly cloudy with flurries, up to 5 cm / southwest winds 30-60 km/h / alpine high temperature near -2 THURSDAY - Periods of snow, 5-10 cm / southwest winds, 10-20 km/h / alpine high temperature near -2
Avalanche Summary
A widespread natural avalanche cycle to size 3 was reported north of Hazelton on Sunday. Another notable report from the same area was of a remotely triggered (triggered from a distance) size 2.5 avalanche on a southwest aspect at 1650 m on Sunday. The report suggests that this avalanche may have triggered two more size 2 avalanches nearby.
Snowpack Summary
Up to 30 cm of recent snow has been blown into wind slabs at upper elevations. Due to previous variable wind directions, wind slabs may be found on all aspects in some areas.In the alpine and at upper treeline elevations, this recent snow likely sits on a weak layer of surface hoar (feathery crystals) in wind sheltered areas. At lower elevations, the recent precipitation fell as rain. The surface has formed a melt-freeze crust below treeline, and into treeline in some areas as well.Generally speaking, areas north of Hazelton received the highest snowfall amounts in the last storm, while the south of the region received less. The northern areas have had more avalanche activity as a result of this, as noted in the Avalanche Summary. The bottom 30 to 50 cm of the snowpack consists of a weak combination of facets (sugary snow) and crusts, particularly in areas where the snowpack is shallow. It may be possible for large triggers such as cornice failures or rock fall to trigger avalanches on this layer.
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.