Polar air & warmth from the sun. Yin & yang?

14th March 2023

(Above) The crags and buttresses at the upper end of Coire Ardair. Lochan a Choire with a thin skin of snow-covered ice.

Today was a good day. A covering of fresh snow again, and great visibility courtesy of clear skies – at least for some of the time. Some interesting snow to look at thanks to being on the cusp of a season shift. Dare I say it, winter into spring? It felt like it. It happens like this most years, of course, but the seemingly incoherent juxtaposition of cold polar air and some noticeable weak warmth from the sun (which is what we had today) is a weather ‘yin & yang’ that always surprises me.

The snow responded to this too. Sporadic drifting at plateau level on light to moderate winds built some thin cold, weak windslab high on south aspects which was then very lightly cooked by the sun (‘sunny-side up’, not ‘over easy’?) and induced a little early consolidation. Yin & yang for the snow too, then.

Some small, low-density (aka weak & collapse-prone) cornices also developed over those south-facing slopes and a few collapsed later in the morning.


(Above) Looking out towards Coire a Chriochairein from Coire nan Gamhna. There’s a fair quantity of soft fresh snow, or lightly drifted snow, at plateau level which may become new raw material for windslab if wind speeds exceed a threshold for drifting overnight Tuesday and throughout Wednesday. The projected wind speeds in our Met forecast hover around that threshold. The published avalanche forecast assumes there will be some drifting. We’ll see.


(Above) The final few pitches of ‘Centre Post’, one of Creag Meagaidh’s best-known winter climbing routes. The coire was quiet today apart from a pair of climbers and a few walkers. One of the two climbers is visible just above the obvious ice pitch.


(Above) For context. Centre Post (centre of photo) is the middle of 3 left-slanting gullies on the Post Face of Coire Ardair. If you zoom in you should be able to spot the two climbers atop the broad tower that separates Centre Post from South Post, its neighbour to the left. I think they’re looking down to admire their handiwork! (Looked like you had a great day!)


(Above) The Big Picture. A covering of fresh snow which melted below 500m over the course of the day.

Comments on this post

  • Keith Horner
    14th March 2023 8:00 pm

    Interesting that as we approach the astrological spring, the coire looks more wintry than it has for weeks……

    Is the second climber belayed below the leader at the icefall directly below the rocky outcrop or is this just an illusion?

    Also, there looks to be a very small crown wall across the top of the basin to the right of the upper section of Centre Post?

    • meagaidhadmin
      14th March 2023 8:50 pm

      It would look more ‘season-appropriate’ if the superficial snow were to be removed. (God forbid!)

      The climber in view was belayed by his leader who is just out of sight close to the rocky left-hand side of the gully. Click on the photo and zoom in and you’ll see the line of the rope.

      Re. The ‘crownwall’. I had a good look at that through the binos. It does appear to be a crownwall but there was no evidence of any debris below it – old or recent.
      My two cents? I think what we can see is the front face of line of snow that had been wind eroded. A bit like sastrugi, the steep face always points into the wind. The winds had been ENE overnight and early morning so I guess that would have been when this feature appeared. The Post Face is a bang-on ENE aspect so would have faced directly into the teeth of the wind.

  • Stan Wygladala
    14th March 2023 11:05 pm

    So much better. Slight warming to come and then cold again; great conditions.
    And……one you haven’t heard before…
    It is better to stand on stable ground wishing you were up on the ice bound rock than it is to be on the ice bound rock wishing you were on stable ground! (Haven’t we all been there! As a logical person I am non-religious but…..have had cause to call on the Almighty to save me. Wears off later.)

    • meagaidhadmin
      15th March 2023 7:36 am

      Many a true word there, Stan.

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