Slow Thaw

24th February 2021

Covid -19
The Scottish Avalanche Information Service issues information to support permitted activity under current Scottish Government guidance.
Please be aware of current mandatory travel restrictions in Local Authority areas within Scotland and respect local communities by referring to Scottish Government guidance and safe route choices for exercise. For further guidance please refer to the following information for hillwalkers and climbers and snowsports on ski and board.
This blog is intended to provide hazard and mountain condition information to help plan safer mountain trips.
Today was mild with a few showers brought in on strong South-South-Westerly winds. The snowpack continues to thaw and diminish with the snow cover becoming increasingly patchy below 800 metres. However, what remains is quite substantial in depth in some places and I was pleased to be on skis regardless.
Despite the changes in the snowpack in the last week, a sortie at higher levels in not without interest. Firstly, the avalanches recorded in recent days in Coire an t-Sneachda are impressive. You may have seen the blog post from Lochaber, Size 2 or Size 3?, which makes some interesting reading. The size of the avalanches in Coire an t-Sneachda are tricky to size as they have overlapping debris piles. The bigger of the two are quite possibly Size 3 (see image below).
Secondly, a number of glide cracks were noticed today particularly on Northerly aspects above 1000 metres. These are indicative of the whole snowpack sliding on the ground or close to ground. It does mean that the whole snowpack in these locations is homogenous, isothermal i.e. zero degrees Celsius and has few layers. Glide cracks are sometimes the precursor to full depth avalanches after prolonged thaws.
As the freezing level drops overnight, we will see firm and icy surface conditions due to a refreeze.

Three separate avalanches in this image. On the left you can see a crown wall stretching under the rocks heading left out of shot, which accounts for the debris marked by a pole in the foreground. Centre there is debris coming from the vicinity of Jacobs Ladder. On the right there is another distinctive crown wall of an avalanche which stretches over towards Alladin’s Couloir.

 

A Ptarmigan going about its day despite a global pandemic and the gale force southerly winds.

 

Still good cover, certainly on the North facing slopes and carries above 800 metres.

 

This small glide crack was pictured at a much lower elevation above the link road. Evidence of down slope “creep” of the snowpack due to ductile flow.

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