[MCR] North Rockies update

Just thought I would pass on a bit of a summary of some snow observations
from the North Rockies from over the last few weeks.

Much of my time this winter is doing industry work around Pine Pass ,
Azouzetta Lake, and the Table River.

Up there we are calling the layer of concern the Jan 22 "melt freeze
Surface hoar combo layer", as this is the date it was buried. 
Around Jan 14-15 there was a wind event along with warm temperatures that
formed a crust on which the SH formed on and then buried.
The SH is not as reactive as it is reported to the south. It is more like
a stiffer crust but with the SH crystals still recognizable. 

It is certainly a visual time stamp to see this crust layer in the pit
wall as it is either somewhat discolored, or has small needles embedded
in it. 
It is about 40-100cm down now, depending on exposure to wind.
I have found this layer from Purden Mountain, to Powder King, on SW
aspects in Pine Pass, and in the Table River both up high and down
low.

Ski touring on Feb 19th at Pine Pass we had a few large whumpfs near
treeline on a SW aspect, but couldn't pin point the culprit to the deeper
PWL. (Persistent Weak Layer)
We found a compression test easy down 20cm in the storm snow, with a hard
result down at the Jan22 layer. It would seem the whumpfing should be
related to the deeper PWL, but we couldn't confirm this with our
tests.
At this wind affected profile site the Jan22 layer was down 40cm at
treeline .

We found the same layer a day earlier at treeline in the Table River,
which gave easy results down 85cm, with a sudden collapse. 

The average snowpack around Pine Pass is about 160-220cm valley bottom
(900m), in the Table River it is 240cm valley bottom (1100m,) and over 3
metres in the alpine. 

We did some avalanche control work near Pine Pass just after the strong
outflow winds started on Feb 22, and only got newer instabilities to
release. So far nothing is stepping down to the PWL , and we have been
trying!
(the winds are still slamming the landscape with gusts near 90km out of
an easterly direction through March 1. ) 

All in all, still expecting this layer to be active or at least remain a
primary concern, but not exactly sure when, or what the trigger will be.
Have been only skiing on well supported terrain, avoiding anything of
consequence and expecting the unexpected, probably like most of you out
there.

Though I haven't been out this week, I expect we will have isolated stiff
wind deposited slabs sitting on top of a mix of  variable layers, or
scoured out to Sustrugi in some normal lee areas...could be some
interesting loading patterns this week. 

Windward? leeward? which is which?

Cheers,

Peter Amann
Mountain Guide

Peter Amann
pamann@xxxxxxxxxxxx

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