When I was an observer the biggest problem I had in winter was getting an ice bulb going when the temperature got close to freezing. Judging by the look of this Stevenson screen (fig 1) they wouldn’t be having that problem at the moment at Izaña in the Canary Islands. It’s not quite as cold as it has been recently (fig 2), but the rime seems to be building up in the northeasterly.
I don’t suppose they are getting very much astronomy done at the moment at the observatory, but that’s at 2,390 metres (7,841 feet) whilst Mount Teide itself rises up to 3,718 metres (12,198 ft), and is the highest point in Spain, as well as being the highest in any island of the Atlantic which of course includes us.
Looking at the very nearby upper air ascent from Guimar (WMO 60018) for midnight (fig 3).
it looks like Izaña is sat in an inversion with a sub-zero freezing layer that’s not quite been captured by the radiosonde ascent by the looks of it (fig 4). Although I will say at this point that my sonde application does need a good-looking at!
You can see from the special points that the temperature is well above freezing at the 779 hPa level, and remains above freezing till around 11,000 feet and just below the summit of Teide it goes sub-zero again (fig 5).
Finally to finish, here’s a satellite image from yesterday of the Canary Islands, I think you can just about pick out Tenerife with some snow cover or is that cloud (fig 6)?
Well it had to be white didn’t it? Although Mount Washington Observatory isn’t particularly high at 1,910 metres AMSL, it is perfectly positioned to catch the fiercest of storm that come down from Arctic Canada or run northeastward up the eastern seaboard of North America, as one low did on Christmas Eve. The above image was of the sunrise on the winter solstice (fig 1), and below is a grid of 6 hourly plotted observations from the 19th through this Christmas period (fig 2).
At this point I always comment on how they can possibly report an accurate snow depth with winds of that force, but in a break with tradition I’m not going to say a thing.
The wake from Caroline is producing 35 foot waves at K5 at 08 UTC this morning (59.1° north 11.6° west) (fig 1). The cold front dropped the temperature almost 9°C in three hours on top of Cairngorm in the early hours (fig 2).
No boy scout worth his salt would have been as foolish to camp out on the Cairngorms last night, and if he had been, he certainly would never have got his tent up in a hurricane force 12 and gusts to 116 mph (fig 3).
Here are the 12 UTC temperature anomalies for 12 UTC on the 12th of November (fig 1) and it’s a cold day everywhere, especially the further east and north that you are. Temperature anomalies are generally in the range 2 to 4°C below the 1981-2010 long-term average for 12 UTC on the 12th of November. But the weather is bright enough away from the east coast and the far southwest, where showers have continued in the fresh or strong N’NW wind.
Meanwhile low Numa continues to track SE and deepen across the south of Germany (fig 2). There’s quite an area of snow developed now in the cold air to the north of the low, I should imagine the Alps are in for a pasting in the next 12 hours.
The BBC news report that a temporary weather station has been installed on the summit of Ben Nevis this Autumn, this is 113 years after the original weather observatory which commenced observations in 1884 closed in 1904.
The AWS looks suspiciously like a Vaisala Weatherhawk (Vaisala WXT536) something I’ve always wanted to replace my aging Vantage Pro with, but something we simply can’t afford my wife says. It stands just a few metres from the summit cairn on what looks like a six metre mast with two huge solar panels bolted on it to provide the power. It looks like the whole thing is a publicity stunt funded by the NCAS and Leeds University to help get a permanent weather station for Britain’s highest mountain. I’ve hunted around on their site, but can’t find any of the data that its reporting. In all honesty it will be little different from the readings that we see from the SIESAWS stations on nearby Aonach Mor (1130* M) or Cairngorm (1237* M) to the east, but then again 108 metres does equates to being 354 feet higher I suppose.
Powering the AWS
The big problem is getting mains power up to the top of the Ben would be very difficult. Even if they dug up the entire tourist route and paved it at the same time, burying the mains cable under it as they did it. No one would want to put pylons up it and scar the whole mountain, the objection let alone the cost would be enormous. Solar power from solar cells might be the best answer, but the Ben is so often cloud covered, and in winter the amount of sunlight those panel would receive would be very small indeed. I shouldn’t think that the transmitter or the sensors would require that much power, but the heating of the anemometer to keep it free of riming would be enormous, and this would be required for at least 75% of the year at a guess. That’s probably why the weather station is being removed in December, I doubt that the temporary structure they have in place at the moment is up to seeing a winter out at 1345 M, the force of wind on those two solar panels must be enormous, and I suspect that if they didn’t take it down it would be blown down anyway.
I wrote an article earlier this week about the fact that there are two weather stations on Cairngorm, one owned and run by Heriot-Watt university and the other by the Met Office. Wouldn’t it be sensible if Heriot-Watt and NCAS collaboratewith one another and move the existing one on Cairngorm (the one that pops up out of a protective can twice every hour) and relocate it to the old observatory ruins on top of Ben Nevis? Of course this doesn’t get round the crucial power problem, which short of installing some kind of small nuclear power cell might always be the problem. They must have power on Cairngorm to run both weather stations, but because it’s close by the ski slopes there is power to the Ptarmigan restaurant at the top of the funicular railway less than a kilometre away. It must have been a tough job but someone must have buried an armored power cable right to the rocky top of Cairngorm to provide power for those weather stations, and did a pretty good job of disguising it because I never saw any sign of them – that maybe the way to go on Ben Nevis?
There must be some weird kind of icing problem going on with the Cairngorm SIESAWS over the last 24 hours, because when things should have been cooling off yesterday the temperature sensor got stuck at around -0.7°C for much of the day and wouldn’t go any lower until 23 UTC last night when it suddenly fell to -3.2°C (fig 2). Equally, the wind sensor has now just stopped reporting at 05 UTC this morning, but oddly the station is still reporting a gust, but no mean speed or direction. The Aonach Mor SIESAWS is also out of action at the moment so it’s impossible to confirm what I suspect.
But then as I am writing this, I do remember that there is there is another way to verify those temperature readings, and that’s with the help of the Heriot-Watt University Physics Department! They have had an AWS on Cairngorm since 1977, that’s the one that pops up out of a big can every half hour to do an observation (fig 3) such a British solution to the icing problem!
The recent thermograph from the Heriot-Watt AWS (fig 4) confirms what I suspected about yesterday’s temperature readings from the it’s very close neighbour the Met Office SIESAWS:
I hope they get the anemometer replaced in their AWS before much longer, they will certainly be hard pushed to replace it this late in the year I fear.
I can’t say for certain, but I would have thought that today was the first time that the high tops of the Cairngorms have seen a dusting of snow this Autumn, but I could be wrong (fig 1). It’s certainly been a very mild Autumn over the mountains of Scotland so far this Autumn (fig 2).
I didn’t expect to find a webcam at the top of the funicular railway at the Ptarmigan restaurant (fig 3) but here’s the evidence of that dusting of snow, although even that could be rime I suppose. I notice that they even have a smart phone app for this season so that you can check out the skiing conditions.