Historical crown walls

2nd April 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.
It was dry but overcast today for our sortie into Coire an t-Sneachda. The visibility was generally good, but the highest summits remained shrouded in cloud for most of the day.
Our journey took us into the coire and up towards ‘The Mess of Pottage’. Here we were able to inspect the impressive crown wall formed by an avalanche that was recorded on the 21st February. Despite the recent rain, we anticipate that at its highest this crown wall is at least 2 metres high.
Tomorrow is expected to be clear and sunny in the Northern Cairngorms. Due to the current stable air mass freezing levels are artificially high, due to warmer air well above the summits. However in reality, a clear night will result in a widespread radiation freeze, creating a firm and icy snowpack from 500 metres upwards. With the best cover above 950 metres, it is likely to be firm and icy everywhere making for consequential travel on foot or on ski. This will be compounded by exposed boulder fields in the coire floors making for poor runouts in the event of an uncontrolled slide or fall.
The snow surface will soften during the day, especially on slopes which receive direct sunlight. Considering the best aspect and timing will be essential tomorrow.

 

The view from Coire an t-Sneachda down towards Loch Morlich. The horizontal bands of snow have accumulated in the wind sheltered (lee) aspect of the lateral moraines in the coire. In the middle distance an irregular snow surface is just visible, which is debris from a size 3 avalanche on the 17th February 2021.

 

A large crown wall from an avalanche earlier in the season. Logged at 21 February 2021.

 

Crown wall below the ‘Mess of Pottage’. This avalanche was a natural release on a persistent weak layer just above the ground following overnight rain on the 21st February 2021. There were similar avalanches at the same time, another crown wall being visible in the top right of the image.

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