A persistent slab problem seems to be emerging in the Chic-chocs. These are particularly difficult to predict and identify.
Be extra careful in the mountains.
Not only can the cold weather accentuate this problem, but it can also greatly aggravate the consequences of an avalanche accident.
Isolated wind slabs are found on leeward slopes and in laterally loaded slopes of the alpine and the treeline. They may rest on old slabs, or directly on the January 18th crust.
With the cold temperatures, facetted grains developed on and under the January 18 ice crust. A size 2 avalanche was accidentally triggered on this interface on January 31 at Mount Logan and we have been getting regular test results showing avalanche triggering potential for the past few days. As with any persistent slab problem, the problem is very sporadic, almost isolated and the spatial variability is significant. It is therefore possible to test a few meters away and obtain completely different results on this crust. The probabilities of triggering are low, but the consequences could be very unfortunate. The problem seems to be a little more important at the treeline, where the snowpack is thinner, near natural obstacles, such as trees or rocks.
A size 2 avalanche accidentally triggered by a skier on Mount Logan was reported yesterday on MIN: https://avalanche.ca/map?panel=mountain-information-network-submissions/bbe4140f-a1da-11ed-9ab2-1e4d977c200f
Thanks for contributing to the collection of this valuable data by sharing with other users on the Mountain Information Network or by writing to us directly at [email protected].
In the mountains, in areas sheltered from the wind, we find 10 to 15 cm of very light snow that rests either on the January 18 crust or on 20 to 50 cm of slightly heavier snow that rests on the January 18 crust. The best conditions are found below the treeline and near the trees line at the treeline.A great deal of spatial variability is present in the alpine and at the treeline, ranging from soft slabs on the surface, to wind-affected snow, to crust, to rock.Facetted grains have developed on and under the January 18 crust, with more and more test results showing reactivity on this crustThe bottom of the snowpack is composed of a laminate of decaying crusts and facetted grains. In general, the height of the snowpack varies from 60 to 80 cm in the valley to 100 to 140 cm at mid-mountain.
Forecast for the Chic-Chocs ridges and summits.
Synopsis: Snow expected Thursday night as an intense cold front passes through. Wednesday evening and night: Partly cloudy. Wind northwest, 30 to 50 km/h. Low -24.Thursday: Alternating sun and clouds, snow in the evening and night, 5 to 10 cm. Wind southwest, 30 to 40 km/h, increasing overnight. High -15.Friday: Clearing in the morning. Wind northwest, 50 to 80 km/h. High -29Saturday: Alternating sun and clouds. Wind northwest, 50 to 90 km/h. High -22.
For more details, check the Alpine Weather Forecast.
