This week I've been working a CAA Level 1 in the Lake Louise/Bow Summit
area.
The week initially started cold and with a fairly stable snowpack.
Fairly unconsolidated surface layers, good mid-pack strength, with the
basal facet and depth hoar layers not very reactive to our tests.
Generally hard shears (although Sudden Collapse in quality).
Rutschblocks were all rated 7 (no result).
We started seeing warming mid-week, and this has led to a subtle change
in the past 24 hours. In addition to the expected loose snow avalanches
on steep sunny aspects, there was a report of size 2 slab on a south
aspect yesterday. Today (Friday) we saw the top 30 cm of snow start to
settle and form a slab but the weaker facetted layers or crusts just
below this slab has not strengthened as fast. So we started seeing
variable shears 20 to 30 cm down from the surface, easy to hard but all
Sudden Planar in quality. This shear was reactive to the skis to and I
cut a size 1 slab 25 cm thick in a steep convex roll on a south aspect
at treeline. It was a very small feature but I think on a bigger slope
with the same snowpack characteristics it would have propagated a fair
ways.
We're saying avalanche danger is Moderate in the Alpine, Moderate at
Treeline, and Low Below Treeline.
Terrain travel advisory: at highest elevations we expect sluffing and
isolated windslabs due to brief intense flurries and moderate south
winds today. Cornices are a concern at all elevations, due to their
size combined with warming and windloading at high elevations. Caution
for settlement slabs that lie on well developed facets on shaded slopes
or suncrusts on steep solar aspects.
Mark Klassen
Mountain Guide
mark@xxxxxxxxxxxx
www.alpinism.com
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