Watch for recently formed wind slabs on a wide range of aspects at higher elevations. Southeast to southwest aspects are the prime candidates for holding the most reactive slabs.
Small new wind slabs formed at the end of the week as a result of elevated northeast outflow winds. Expect to find these in the immediate lee of exposed terrain features at higher elevations.
Isolated steep features in the alpine that did not avalanche during the previous natural cycle may still have potential to produce destructive persistent slab avalanches with a human trigger. Increase caution around steep alpine slopes where a supportive crust layer does not exist near the surface.
Friday night: Becoming cloudy with light flurries beginning. Moderate east winds.
Saturday: Cloudy with continuing scattered flurries bringing up to 5 total cm of new snow, easing overnight. Light east or northeast winds, easing over the day. Alpine high temperatures around -10.
Sunday: Cloudy with isolated flurries and a trace of new snow, increasing overnight. Light east winds, increasing overnight. Alpine high temperatures around -6.
Monday: Cloudy with easing flurries and up to 10 cm of new snow from the overnight period. Light east winds. Alpine high temperatures around -5.
A MIN report from the Ledge Basin area on Thursday described small new wind slabs triggerable in leeward features at higher elevations, a product of recent northeast outflow winds. Similar conditions were observed on the North Shore on Friday morning.
There have been no other reports of avalanche activity in the region since early last week when a widespread natural avalanche cycle up to size 3 (very large) took place in the North Shore mountains. Dense bridging layers of snow and crust are expected to have effectively neutralized the problem since that time, although some uncertainty exists with regard to higher alpine locations.
Elevated northerly winds on Thursday redistributed limited loose snow into small but reactive new wind slabs in the immediate lee of exposed terrain features at higher elevations.
The snow surface otherwise consists of a thin cover of low density snow (where not windblown) over a mix of thin breakable crust, old wind-affected snow, and older wind slabs that have been losing cohesion under the influence of prolonged cold temperatures. 30-40 cm of gradually faceting storm snow below this surface, a more supportive crust solidly caps the snowpack below about 1400 metres. This crust may be absent at higher elevations.
100-150 cm of snow sits over a widespread persistent weak layer. This weak layer consists of a thick crust with weak facets on top of it in many areas. In most areas where it remains preserved, this layer is likely not triggerable due to bridging by overlying dense snow and crusts (this applies to the North Shore). There is some concern for the possibility of continued reactivity in steep terrain at higher elevations in the interior and north of the region where it has not previously avalanched and where the overlying snowpack may have failed to form an effective bridge over it.
Click here to check out North Shore Rescue's snowpack update from February 12. It's an excellent snapshot of current conditions on the North Shore.
