Strong winds and new snow available for wind transport have heightened the avalanche danger rating and will continue to build upon already reactive windslabs.
Adopt a conservative terrain travel strategy that avoids steep north aspect terrain and seeks out low-angle well supported terrain.
With the arrival of southerly wind, we have seen rapid wind slab formation in lee areas. Assess for changing conditions throughout the day and as you gain elevation or change aspects. Use extra caution in leeward terrain features.
On Wednesday our field team observed a widespread natural avalanche cycle in the high alpine that was confined to north aspect and cross-loaded terrain features. These avalanches were small ( mostly size 1 to 1.5 ) But a few noted large avalanches occurred ( size 2). Everything observed, ran fast and far through the soft and faceted lower elevation surfaces.
The upper snowpack consists of 5 to 15 cm of new storm snow that overlies another 10-15cm of old unconsolidated faceted snow. The midpack presents as very dense with a reactive mid-December layer buried down between 40 to 55 cm.
Snowpack depths vary due to wind transport with averages at treeline reported as 125 cm and 200 cm in the alpine. In areas where the snowpack is less than 1 meter in depth, it is reported to be quite faceted and unconsolidated.
Thursday night
Mainly cloudy with snowfall, up to 5 cm of accumulation. Southerly winds maintain between 50 and 70 km/h. Alpine temperatures rise to -5 °C. Freezing level rises to 500 m.
Friday
Cloudy with snowfall, up to 5 cm of accumulation. Strong southerly winds continue at 60 to 80 km/h. Alpine temperatures around -1 °C. Freezing level rising to near 1500 m.
Saturday
Cloudy with snowfall, between 10 to 15 cm of accumulation. Southerly winds are initially up to 100 km/hr easing 20 to 40 km/h. . Freezing level falling to 500 m. Alpine temperatures are around -5 °C.
Sunday
Cloudy with light snowfall, up to 3 cm of accumulation. . Southerly winds easing 20 to 40 km/h. Freezing level near valley bottom. Alpine temperatures are around -12 °C.
More details can be found in the Mountain Weather Forecast.
