The thaw begins as temperatures warm through the week. Watch for increased wind Tuesday as it may add to the existing windslab problem or trigger small loose dry avalanches.
Reactive windslabs were found in immediate lees in the Sunshine and Lake Louise regions on Monday. Forecasted wind Monday night into Tuesday may contribute to the problem and may trigger a few loose dry avalanches. There is still snow available for transport from last week's storm of 10-40 cm.
The base of the snowpack consists of weak facets and depth hoar, and there has been some activity on this layer over the past week. Use caution in steep terrain or planar slopes where failures in these basal facets are more likely to propagate. Especially watch thick to thin areas.
Snow safety teams at Lake Louise and Sunshine triggered small windslabs on Monday in immediate lees with ski cuts and explosives. Several loose dry natural avalanches to size 1 were also reported.
Late last week, after the storm, there were several avalanches to size 2.5 on multiple aspects, and some are suspected of sliding on Dec 31 surface hoar, with some stepping down in the alpine to deeper layers. Most were 30-40cm deep, with some stepping down (80 cm thick).
Mod-strong winds in the last week have formed slabs at treeline and above. 20-40 cm of recent snow over the Dec 31 layer that is comprised of surface hoar in sheltered areas and a spotty sun crust on steep solar slopes at treeline and above.
The mid-pack is supportive and contains two temperature/rain crusts from Dec 22nd and Dec 5th that reach as high as 2350 m.
The base of the snowpack consists of weak facets and depth hoar in most areas.
Treeline snow depths range from 80-120 cm.
The winds have switched to a Westerly flow and the temperatures have started to warm. Expect moderate to strong W-NW winds Tuesday. Tuesday's highs will be around -15C with 2-4 cm of snow. Tuesday night into Wednesday we may see 10 cm.
For more information, click Mountain Weather Forecast.
