Sustained heavy thaw continues

18th December 2015

Hide(Above) Come across this hide en-route to Sron a Ghoire today. The stalkers at SNH Creag Meagaidh use it when culling deer at low altitudes on this hill. Sustained thaw has taken its toll on the remaining snow patches – noticeable snow loss pretty much everywhere today.

SNG slab(Above) One of usual full depth avalanche suspects. This sizeable snow patch overlies steeply inclined rocky slabs and is the site of at least two full depth avalanches last winter. Today’s pit was dug in a safe location on the smaller isolated snow patch on the left hand side of the main patch (pit just visible).

Full depth avalanches – if we’re honest – are still a bit of a mystery to us so it was good to gather some pretty focussed field data today. Conditions (that is, the amount of free water) at the snow/rock interface are critical but we have to add to  that: snow density, the tensile strength of this dense snow, the angle of inclination and the surface roughness of the ground. The snow/rock interface was very wet indeed today but glide cracks here were for the most part minor/insignificant.

The build up of dense old snow is pretty modest in this location in comparison to last year’s big events.

FD debris1(Above) Part of the track of last winter’s full depth avalanches.

There’s been a fair amount of natural regeneration of heather, grasses, mosses etc but there’s plenty of evidence of where the big blocky avalanche debris bludgeoned its way through this area. The deposition, or runout, zone here measures approximately 30m wide by 80m downslope. Mounds of turf and un-weathered rocks/boulders (visible above) are plentiful here.

FD debris2(Above) A small example of an un-weathered rock plucked from the rocky slab and carried 250m down hill.

FD debris4(Above) This 250kg boulder was unceremoniously hauled out of it’s periglacial resting place by one of last year’s big events. To its left, another un-weathered block that had probably been ripped out of the rocky slabs in the start zone and carried down 250m.

Hoping for the return of colder and more seasonal conditions although the short term forecast isn’t looking too promising.

Got a couple of days off so I thought I’d leave you with a little video message I came across recently from one of our North American avalanche compadres. There’s a few things in it that don’t quite fit the Scottish context but there are some important and timely sentiments worth taking on board as our winter season gets under way.

(Best enjoyed in High Definition.)

Comments on this post

  • Grant Duff
    18th December 2015 7:43 pm

    It’s amazing just how quickly the snow melts away since last weekends drop, although crazy temperatures do that I guess. It will be interesting to see if like last year there are such regular dumps of snow on the tops although this year so far it isn’t looking promising.

    Some great photos and info as usual on this blog.

    Bring on more snow!

    • meagaidhadmin
      18th December 2015 10:16 pm

      Thanks for your comment, Grant.

      Yes, the weather has been a bit weird so far.

      The Met Office stopped publicising their 3 month weather outlook (probably because the general public didn’t understand the difference between weather ‘outlook’ and ‘forecast’) after the ‘barbecue summer’ they touted a year or two ago turned into something quite different! However, they still produce these long-range outlooks but tuck them away in a Met Office blog. According to a blog posting in late October the coming winter is likely to be mild and wet to start (…correct so far then) and colder in the latter part. Have a look here:

      Makes interesting reading.

  • Grant Duff
    19th December 2015 9:46 am

    Hey Meagaidhadmin,

    The Met Office seem spot on and January still looks promising.

    Thanks for the link.

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