This conditions posting is a day or so late but I felt that the observations are still relevant.
Skied at the headwaters of Molliet Creek on Monday Dec 13th, the day after heavy storm snow loading in this region. Total storm snow amounts from the weekend are up to 40 cm at tree line, bringing the snowpack height to about 140 cm at TL in this area. Air temperature at 2100m mid-day was -5.0c
Extensive west to east (traditional) loading pattern from moderate to strong winds last Sunday. Wind effect occurred above tree line and in open areas below tree line producing hard slabs on windward slopes and soft slabs in leeward terrain above 1900m.
Storm snow was settling rapidly with widespread observations of "settlement cones" around the base of trees. These are small fractures that appear around basal branches of conifer trees, this can be due to the rapid addition of snow "load" on softer weaker snow below.
I did not spend time conducting detailed snowpack observations such as compression tests. Ski cutting on short steep convex features in treed terrain did not produce fractures and I did not experience any "whumpfing".
The "Fro" bowl ran size 3 with debris close to the normal run out. This natural slab avalanche occurred "mid-storm" as the fracture line was already partially filled in and the toe of the debris had snow accumulation on it. This avalanche was in skiable terrain, north aspect between 2100 and 1650m. The neighbouring bowl "Carolines" also cleaned out but not as extensively with debris only reaching mid-path. The depth of the fractures were 40cm on average by "eye balling it". There were also a few size 1.5 and 2.0 natural storm snow releases below rock bands in steep un-skiable north facing terrain at tree line elevations. I observed one size 2.0 avalanche on a north aspect at least 45 degrees that ran to the ground in rocky un-skiable terrain at about 2000m, this was very isolated.
The storm snow has significantly improved coverage over ground obstacles below tree line. Ski quality was good in protected areas.
The new load on softer weaker snow below may still just be waiting for a "human" trigger in specific terrain features such as steep lee tree line and alpine terrain and skiable un-supported terrain at all elevations and aspects.
Dana Foster Ludwig
Ski Guide
Snowy Mountain Alpine Tours
Blue River - Clearwater BC
P 250 674 2988
www.snowymountain.ca