Strong winds and new snow available for wind transport maintain the current avalanche danger rating and will continue to build upon already reactive wind slabs.
Adopt a conservative terrain travel strategy that avoids steep north aspect terrain and seeks out low-angle well supported terrain.
Past and continued strong southwesterly winds have encouraged 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.
Sunday, A mountain information network report outlines both conditions and the observation of a naturally occurring small (size 1) avalanche. This avalanche appears to have failed near the ground and was reported to have occurred on a northeast aspect in the Fraser lakes area. See embedded MIN for pictures and review.
Saturday reports provided by the Skagway white pass avalanche control program, indicate that utilizing explosives 26kg or greater initiated numerous large avalanches (size 2 to 2.5).
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 (size 1 to 1.5), and a few noted large avalanches occurred (size 2). Everything observed, ran fast and far through the soft and faceted lower elevation surfaces.
A strong southerly wind has continued to transport available new snow that has cross-loaded and created wind slabs at depths reported between 60 to 70 cm.
These new accumulations overlie an upper snowpack consisting of 15 to 30 cm of both new storm snow and 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.
The onshore flow and low-level moisture will deliver up to 15 cm of new snow to the southwestern-facing front-range slopes. As the storm rapidly progresses east, precipitation amounts will generally be light, estimated at 5 cm on the east side of white pass.
Monday night
Cloudy with snowfall, up to 15 cm of accumulation. Southerly winds continue at 60 km/h to 80 km/h. Alpine temperatures are around -4 °C. Freezing level rising to near 500 m.
Tuesday
Cloudy with snowfall, 1 to 5 cm of accumulation. Southerly winds continue at 60 km/h to 90 km/h. Alpine temperatures are around -4 °C. Freezing level 500 m.
WednesdayCloudy with snowfall, up to 5 cm of accumulation. Southerly winds continue at 60 km/h to 80 km/h. Alpine temperatures are around 0 °C. Freezing level 1000 m.
ThursdayCloudy with snowfall, and trace amounts of accumulation. Southerly winds continue at 60 km/h to 80 km/h. Alpine temperatures are around -4 °C. Freezing level 500 m.
More details can be found in the Mountain Weather Forecast.
