Avalanches & collapsing cornices.

24th January 2024

(Above) High tide at Kingussie shinty club! Floodwater innundated this low lying ground next to the river Spey this morning. Up to this point the Spey only receives runoff from the River Calder (from the Monadliath mtns) and the catchment of the Creag Meagaidh massif. It had been raining a lot overnight at Creag Meagaidh and unusual weather events like this can be a precursor to avalanche activity, especially if it rains immediately after snowfall or drifting.


(Above)  Overnight cornice-triggered wet slab avalanche in this moderately steep NNE-facing gully near Puist Coire Ardair. Rain on snow (aka transitional) event, running out 450m


(Above) Raeburn’s Gully, Coire Ardair. Similar aspect to the previous avalanche and as far as I could tell not cornice triggered. Also transitional and likely occurred late on the 23rd Jan.


(Above) Debris from the Raeburn’s Gully gully seen in profile and viewed from Easy Gully. Ran out approx a total of 450m and onto the talus fan below.


(Above) Easy Gully. Coire Ardair. A loose snow event beginning where the gully steepens up above the popular ice route ‘Last Post’ (in the photo, the wide curtain of ice that descends into the gully). Same timing, I think, as the others. In this instance the avalanche picked up more snow as it transited down the gully. Some bits and pieces of loose snow also fell down out of ‘Centre Post’ – just to the right of the Easy Gully debris tip. (There was also a suggestion of some minor wet slides in the Inner Coire but I wasn’t able to get a good enough view to confirm them).


(Above) Cornice debris from a few sizeable collapses on the S-facing aspects of Coire Ardair. There’s also a biggish cornice debris tip over on the right of shot. As you can see, cornices still remain in place.

Dry overnight conditions should encourage further consolidation of snow in most places. There will be some limited wet snow instability after the rain and mild temps kick in during Thursday morning. Those remaining cornices (some large) will all remain prone to sudden collapse. Also, cannot rule out minor full depth avalanches from the steep crags of the Post Face.

How come Low Hazard then?

Cornices are a separate mountain hazard not covered by the avalanche scale. They’re fickle beasts which can collapse suddenly in mild, wet conditions…but sometimes they don’t and just hang around, slump and slowly, harmlessly, decay. Full depth avalanches – often a worringly large spectacle when they slide – are similarly fickle and outside our remit for similar reasons.

Comments on this post

  • Mark Worsley
    24th January 2024 7:10 pm

    Thanks for that explanation
    Given their serious potential, should cornice collapse and full depth events not be incorporated into the overall risk to give a fuller picture?
    Asking for a friend

    • meagaidhadmin
      24th January 2024 7:45 pm

      Good question.

      All avalanche forecasting agencies exclude cornices and full depth avalanches from their hazard asessments/forecasts.

      Incorporating them into the overall hazard rating is problematical simply because of the unpredictable nature of their occurence (that is, when they collapse or slide, or not). We deal with a lot of uncertainty when we’re thinking about the likelihood of conventional avalanches and adding a ‘wild card’ factor would make quite a few of our forecasts extremely pessimistic (read as, crying wolf). Whenever either of these two mountain hazards seem to be raising their heads we endeavour to make mention of them, like now.

      Hope your ‘friend’ is happy with this answer!

  • Mark Worsley
    24th January 2024 7:56 pm

    Thanks for that
    It makes sense to include that stuff in the adjoining comments as you do.
    I’ll explain this when my mate returns from the pub

  • Ruth Love
    24th January 2024 9:28 pm

    Yes, like in the lottery results. Do the main numbers results and then do the bonus/lucky or in avalanche terms, unlucky numbers equating to cornice collapse and full avalanche risk! An extra rating or scoring. I think this is, as Mark states, very important. I hope people read the full reports and not just look at the slices of cheese diagram.

    • meagaidhadmin
      24th January 2024 10:46 pm

      Interesting and thought-provoking response, Ruth.

      The SAIS Co-ordinator and a bevy of outside experts have looked quite forensically at the way the public access, interpret and use our messages about avalanche hazard. We know how long you all linger on each page of the website, which parts of the page gets most attention and where you scroll to next. I believe less than 20 seconds is spent on the avalanche forecast page (from memory, confirmation required!).

      From various polls of our users, it’s become really clear that quite a lot of people have difficulty unpicking the basic avalanche hazard message we’re putting out to our mountain user audience via the website. The central avalanche hazard graphic – the pizza, or your slices of cheese, Ruth – is a thing of mystery (or at least not very clear) to a sizeable number of the mountaineering public. That may surprise you but the results of the number-crunching on this are compelling. Quite a few of you find our written reports challenging too and often skip over them.

      What we’ve found is that people require a simple message. Adding an additional scoring/rating system for cornices and full depth avalanches…to stand alongside the existing avalanche report and forecast…could lead to total information overload, a situation we desperately want to avoid.

      *Relevant factoid. Our blogs receive waaay more hits than the formal report/forecast pages. No surprise there. The tail now wags the dog! People like images and seem to process them more easily than an allegedly abstract graphic & several paragraphs of words. For instance, look at the picture at the top of this blog posting. It tells you everything you need to know about what the weather was like overnight: a simple but powerful visual statement. You won’t be surprised to learn that some forecasters now incorporate the avalanche forecast – or relevant snippets of it – into their blog postings.

  • Ruth Love
    6th February 2024 5:47 pm

    Meant to reply days ago, sorry. Thanks for all this. It really does explain things very well. I was having a bit of a joke of course, after a glass of wine but there is a serious element too. I and my husband Simon, took part in the original avalanche conference at Glenmore Lodge years ago when all of this was discussed. It was from that conference that the latest forecasting system came. I like to think that my doodling and diagrams I handed in at the end, with the ‘pizza’ and all it’s colours, was in the main part my idea! I didn’t include the heights but I did have the circle, direction and colours on the diagram. Someone asked me if I was an art teacher! I’m not! Perhaps some of you were at that conference. Thanks again team. Much appreciated.

    • meagaidhadmin
      6th February 2024 6:59 pm

      Yep, I was there, Ruth. I remember it very well.

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