Avalanche Forecast

Moderate - Due to the number of field observations

WEDNESDAY: Cloudy early morning with trace snowfall then mostly sunny, moderate to strong northerly winds, alpine temperature near -5 C, freezing level below valley bottom.THURSDAY: Partly cloudy with increasing cloudiness, light to moderate northwesterly winds, alpine temperature -4 C, freezing level below valley bottom.FRIDAY: Cloudy with early-morning snowfall, accumulation 10-15 cm, light to moderate westerly winds, alpine temperature near -3 C, freezing level near 500 m.

A few wind slab avalanches were reported on Monday, being triggered naturally and by heavy loads.  They were small to large (size 1.5 to 2), up to 1500 m in elevation, and up to 1 m deep.  Many small to large (size 1 to 3.5) wind slabs were reported on both Saturday and Sunday in lee features and cross-loaded terrain on southerly to easterly slopes.  The avalanches were triggered naturally and by skiers.Avalanche activity may increase with warmer air temperatures and forecasted clear skies. Watch for steep sunny slopes due to the sun’s influence, lee features for reactive wind slabs, and be extra cautious near thin spots and shallow snow pack areas where triggering a deeper weak layer is more likely.

Strong northeast outflow winds redistributed the 40-60 cm of storm snow from last week and weekend.  The winds produced touchy wind slabs in lee and cross-loaded features.  The recent cold temperatures are helping to break down these wind slabs, but stiff slabs will likely remain reactive to light and heavy loads where preserved.  The wind slabs sit on a wide variety of surfaces, including wind-scoured and old wind slabs at higher elevations, a sun crust on steep solar aspects, and facets and surface hoar in sheltered locations at treeline and below treeline elevations.  The surface hoar and facet layers are found around 20 to 40 cm as well as 60 to 110 cm deep and on all aspects and elevation bands.A deeply buried crust/surface hoar layer from mid-January exists in sheltered areas at treeline and below treeline elevations.  Thin spot triggering is the primary concern for this layer.