Polar air & warmth from the sun. Yin & yang?
14th March 2023
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!)
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