Enjoyed a morning ski tour up the lower
flanks of Mnt McPherson today. Although the ski quality was quite good,
the Feb 4th surface hoar/ facet layer was beginning to get a bit
cranky. A sign of what appears to lie ahead…
As of noon today there was aprox 20cm (below
tree line) and 25-30 cm (at tree line) of new snow overlying the Feb 4th
interface. Surface hoar is 8-12mm and is mixed with faceted grains.
Only observed north and easterly aspects. Shovel and compression tests
Very Easy.
But most importantly, ALL areas without
tracks were settling, cracking and failing on this layer. Lower down it
was simply shooting cracks and subtle whoomphs. But as we climbed higher
and the amount of snow overlying this layer increased (25 cm), we began to see
the first skier remote slabs. Mostly size 0.5 soft slabs, with two size
1.0. Triggering would occur from distances as far as 25 meters.
Today was mostly a fascinating example of
the characteristics of buried surface hoar, with the hazard easily managed.
(At least in the moderate terrain we were exploring). However, in more aggressive
terrain, in a terrain trap, or as this layer receives additional snow fall, be
aware! It’s a layer to watch and treat with respect. With the
large crystal size it’s likely to stick around for a while and is also likely
to live up to the tricky reputation that classic surface hoar layers have.
Play safe this weekend! J
Cheers,
Paul Norrie
ACMG
Mountain
Guide