I've been on the road ski touring for a few weeks. I just returned
from Whitecap Alpine in the South Chilcotins (McGillivray Pass) a few
days ago and am at Rogers Pass right now.
The snowpacks across the western ranges from the Rockies to the Coast
seem to share similar characteristics and issues. At McGillivray Pass
last week we had the Feb 8 and Jan 25 surface hoar at about 20 and 40
cm respectively. The Feb 8 surface hoar layer (3mm to 8mm, well
preserved) was reactive to skiing, resulting in numerous controlled
and accidently avalanches to size 1.5, but none of these stepped down
to the Jan 24 layer. We stuck to supported and/or small features but
nonetheless pretty much everything >35 degrees resulted in slab
avalanche propogation. Propogation tended to be fairly reluctant:
typically restricted to close to our ski tracks, and usually after the
second or third skiier down the run.
A couple of weeks ago I spent several days in Rogers Pass and noticed
the same surface hoar layers at approximately the same depths as we
had at McGillivray Pass. Surface hoar seemed much more prevalent and
reactive in the Connaught Ck drainage (Bruin's, Ursus) than on the
east side (Asulkan, Loop, Lilly) where we had trouble finding it.
Over the past week the previous surface, which had various crusts and
surface hoar, was covered by another 15-20 cm by the looks of things.
Yesterday we skied via Perly Rock to about 2800m below the Terminal
Peak bergsrchrund. The due south facing slope held a thin crust
starting at this elevation where the slope angle exceeded about 25
degrees. Steep (>35 degree) solar aspects showed evidence of
widespread cycle to size 1.5ish. Otherwise ski quality was good on low
angle west and northwest aspects down to treeline where it was
terrible -- heavy and wet. A few hand shears en route and a test
profile at 2800m revealed patchy small surface hoar down about 30cm to
2mm in size with moderate to hard sudden planar and resistant planar
fracture characteristics. We skied smaller alpine features to 33
degrees with fair confidence (mainly due to the widespread issues
across Western Canada and my recent experiences at Whitecap!) There
was no recent skier traffice in the area.
Today we ventured up the Lilly and down the Dome. Again, all previous
traffic had been covered by the last storm and winds from a few days
ago. Despite the wind effect, skiing down the Dome was very good to
excellent until treeline where it sucked. We skied supported alpine
features to 33 degrees. Of note was a size 2.0 slab avalanche on the
far north end of the Dome area. It looked to be on the Feb 24 surface
hoar layer probably 20cm down and likely at least a couple of days
old, but I didn't get a good look at it. I did not find surface hoar
on our ski run down in a test profile dug at approximatey 2500m down
70cm at the top of the big roll.
F/F/VG, stability deteriorating quickly on solar aspects and below
treeline in the afternoon with warming.
Regards,
Tom Wolfe
AAG/ASG
_______________________________________________
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