Northern Cairngorms Blog & Mountain Info

Poor Visibility…

7th January 2025

Another poor visibility day in the Northern Cairngorms, certainly above 750 metres. Overnight, we estimated that there was potentially a further 15cm of snow and snow showers have continued through the day.

Westerly and West-North-Westerly winds have resulted in windslab accusations on sheltered (lee) aspects above 800 metres. Due to the cold and light snow being redistributed upslope, we have also included all aspects above 800 metres, as windward slopes also exhibit localised but weak windslab. Hazard categories aside the Northern Cairngorms has a developing windslab avalanche problem on multiple aspects.

There is more information on Avalanche Problems on the SAIS website here at: https://www.sais.gov.uk/avalanche-problems-explained/

Due to variations in windspeed there is slightly firmer (more cohesive) windslab overlying very soft windslab or loose snow. This structure is inherently unstable, and it was no surprise to see cracks from failures in the weak layers at depth.

Travel advice for windslab problems is often to avoid snow drift deposits and chalk like wind loaded slopes in steep ground. But a “see and avoid” strategy relies on good visibility and confidence in the ability to recognise windslab. A tricky situation in the current “pea soup” conditions in the Northern Cairngorms…

A party of walkers on the modest summit of Airgiod-meall at 644m. Note the South and South-East aspects on this summit have caught the snow even at this altitude. These slopes being in the lee of the West-North-Westerly winds. Note also signs of drifting snow on the skyline (extreme left of the photo).

A snowy scene in the ski area. Even below the cloud base at this altitude, it was a slightly grey day due to the snow laden skies.

Cracking windslab on an aspect facing into the wind. The windslab is more cohesive on the top, with very soft and light snow below. This proves to be a structurally unsound for obvious reasons, and weaknesses were observed today at multiple heights within our profile.