Hi All,
We just finished a fine ski touring week at the Valhalla Lodge in the Southwestern Selkirk Mountains (Dec 26th-Jan 2nd). Below is a summary of our observations.
Weather:
We enjoyed some clear weather early in the week, at times windy in the Alpine, and some snowy/stormy conditions for the second half of the week. Daytime temperatures at the Lodge (2100m/6900ft) were near zero early in the week and oscillated around -9.0 for most of the week. As this last system moved through the area, Moderated to Strong southerly winds near ridge tops picked up and temperatures rose closer to zero again.
Snowpack:
Snowpack height at treeline in the area was 165cm, a pretty average value there. During the storm that lasted from December 28th to January 2nd, we received 40 to 50 cm of new snow. This new snow was generally evenly distributed at treeline and below. Some exposed treeline areas near ridge top and most alpine areas saw lots of snow redistribution and slab build up from the Mod to Strong southerly winds. This new snow is overlying a variety of suspect surfaces like; variable wind slabs or wind affect above treeline, recent surface hoar to 20mm and/or sun crust on steep solar aspects at treeline and below. This interface is our next/current problem layer and should be carefully monitored in the near future. The December 12th facet layer, now 10-15cm thick, was found 75cm down from the surface. The mid and lower snowpack was generally stiff and well settled.
Snowpack tests showed Easy (resistant planar) shears down 40cm on the December 28th surface hoar layer and Hard to Very hard (sudden planar) shears down 75cm on the December 12th facet layer. Shears on the December 12th facets seems to be gaining strength over the course of the week.
Avalanches:
Earlier in the week we saw evidence of the December 20th natural avalanche cycle with several old size 2-3 slab avalanches both above and bellow treeline on NE to SE aspects. December 28th was windy above treeline. Small but touchy soft and hard slabs developed in steep lee slopes of southerly winds. We felt several moderate size whumpfs at treeline throughout the week, less as the week went on (we suspect the December 12th facet layer). As the storm progressed, we saw some natural and skier triggered sloughs in steep terrain to size 1.5. As it intensified and warmed up later in the week, we pulled back from challenging to simple terrain. We observed some minor surface cracking with significant slab development in lee slopes from southerly winds near ridge top. By the time we left this morning, we hadn't seen any new slab avalanches.
This will likely change/is changing in the near future as the December 28th surface hoar layer gets buried deeper and the slab above it consolidate. As this occurs, the risk for human triggered avalanches will increase.
In the meantime, keeping an eye on the weather trend is advised. There is plenty of great skiing to be add on simple terrain.
Happy new year!
David Lussier
Mountain Guide
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