What you would give for a Shanwell ascent to get an idea of the lower boundary layer of the atmosphere in the last day or so. The nearest upper air station, and the only one in Scotland, is the one at Lerwick. Where’s the logic in that? The northern Isles can have it’s own radiosonde station but not it’s own weather radar? You would imagine that the weather radar would be more useful and the radiosonde station would be no worst being reinstated at Stornoway. Anyway I digress because I thought I would see what was going on across the top of one of our highest mountains this morning – Cairngorm.
As you can see from the Cairnwell observations the inversion descended overnight at the Cairnwell (928 M amsl). There’s obviously a very sharp sub-zero nose to the inversion and the temperature there late in the night lowered to -3°C. That gives us a good approximation of the top of the inversion being at around 950 hPa (~1000 M amsl) because Cairngorm (1237 M amsl) just about managed to stay clear of it. Aonach Mor much further west is not that representative being in the clear and furthest from the low cloud in the east. temperatures at Cairngorm are now back above zero with a dewpoint close to -20°C at 08 UTC (19% RH). It must be quite a scene this morning looking westward toward Ben Nevis, with Braeriach and Ben Macdui standing clear of the cloud across from you. Winds are still unusually light at the moment on Cairngorm itself which probably does explain some of the high spurious temperatures that we’ve been seeing in the observations from the SIESAWS in the last 24 hours.