Topsy turvy

8th February 2015

Cloud and misted rolled in and out repeatedly during the day.

Cloud and mist rolled in and out repeatedly during the day. Shiny surface at this altitude was corn snow.

Air, snow surface and deeper snow temperatures are all over the place at the moment. We had a sharp frost in the glen overnight (the Met station at Tulloch Bridge recorded -3.8 degrees C. at 6am) and barely below freezing summit temperatures. An increase in the wind speed later pretty effectively mixed the air, including the temperatures, across all altitudes later. The upshot of all this was some scratchy skinning on crunchy snow this morning at Aberarder, which relented above about 600m to 850m, then firmer again nearer summits. Had the whole gamut of surface snow conditions to ski on from hard snow ice to firm slab as well as some proto-corn snow quite often at unexpected altitudes and times of day.

The anti-cyclonic conditions we’re experiencing at the moment (including freshening winds) are certainly producing some upside-down weather and snow conditions.

Full depth glide cracks on Sron a Ghoire at 750m.

Full depth glide cracks on Sron a Ghoire at 750m. Approx 1.5m deep

Glide cracks can appear quite alarming if you unexpectedly come across them as one hillwalker did in the last day or so (footprints just visible in the photo deviating around these gaping chasms). What the photo doesn’t show well is the buckling of the deep snow below the glide cracks where the slowly descending slab piles up into less mobile, better anchored snow downslope.

The glide cracks can persist for ages or the slab downhill of them fail suddenly releasing a full-depth avalanche. It’s a bit of a crapshoot, really. The SAIS doesn’t pretend to predict full depth avalanches because, like cornices, it’s really difficult to measure the forces and understand the mechanics involved. What we do know is that they often release when there’s sufficient free-water around to lubricate the bed-surface, often when it’s milder then….but they surprise us all the time, hence the gambling analogy.

Comments on this post

  • Grant Duff
    8th February 2015 7:20 pm

    Full depth glide cracks, I shall avoid in future. Your excellent blog not only provides information but also an education. Fantastic.

    • meagaidhadmin
      8th February 2015 9:58 pm

      Thanks for your kind comment and enthusiastic support for the blog, Grant.

  • Richard Limmer
    9th February 2015 10:30 am

    Fantastic information and advice! Very jealous of your office…. any vacancies?

    • meagaidhadmin
      9th February 2015 5:24 pm

      Not always great weather in our ‘office’, unfortunately!

      When Shackleton was recruiting for one of his expeditions to Antarctica he is alleged to have put the following advert in ‘The Times’:
      “Men wanted for hazardous journey, small wages, bitter cold, long months of complete darkness, constant danger, safe return doubtful, honour and recognition in case of success.”

      So, in the spirit of Shackleton, an advert for additional SAIS personnel at Creag Meagaidh might read as follows (suitably adjusted to be completely PC of course):

      “Men and women wanted for arduous endeavour, modest wages, bitter cold, torrential rain, long months of complete knackeredness, constant hunger, Health & Safety doubtful, honour and recognition unlikely.”

      (Desirable extra qualities: strong legs, big lungs, broad back for that gorilla rucksack, thick skin, relentless optimism and inexhaustible enthusiasm for walking uphill in really crap weather. Knowledge of snow and avalanches an advantage.)

      Seriously, all the people who work for the the SAIS have not had traditional career paths – far from it! Anyone aspiring to do this job nowadays would need to be skilled and experienced practitioner in all aspects of Scottish winter mountaineering. In addition, you’d sacrifice 3 or 4yrs of their life hanging around one or more of the 5 SAIS areas getting to know the forecasters & then pestering to accompany them out on the hill – for no money – on wet, bleak mid-week days in December when there’s no snow. If they find you enthusiastic, and not objectionable company, after a couple of seasons they may allow you to carry their rucksack….and you might even learn something about snow. If you also got yourself off to Canada at some point and picked up a useful CAA qualification or two it would help your cause enormously. Otherwise become a UIAGM Guide (preferably morphing instantly in to an old one with loads of experience!) and you might just pass muster.

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