[MCR] South Rockies/Lizard Range...Potential for deep slabs

Spent this last week in the Fernie area teaching a ski touring course. Observed the March 14th melt freeze crust and March 16th preserved graupel layers get buried.

Through the week we received up to 100cm of storm snow. Mostly falling March 19/20/21. The storm started cool, warmed up the day of the 20th and this morning was -12. Moderate ridge top Winds switched from SW to Northerly.

We had limited observations in the Alpine. Steered very clear of over head exposure due to start zones wind loading and cornice growth. Most of our travel was Below Tree Line ridged features or supported low angle treed slopes.

In the snowpack is a preserved graupel layer about 80 to 100cm deep. 20 cm below that is the 10-20cm melt freeze crust becoming thinner with elevation. Neither produced shear results in tests but with new load is becoming reactive to skier traffic.

Today Below Tree Line at 1600m a size 1.5 was accidentally triggered. What started as a soft storm slab 50cm deep steeped deeper down another 60-80cm. Skiing a lesser angled slope one person at a time, the last skier skimmed a steeper open slope and that's all it took. This feature was small and short.

The next few days or longer will be touchy. A triggered avalanche
in open steep features will likely be deeper then you expect.

Take good care out there.

Merrie-Beth Board
ACMG Ski Guide

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