A cold day in November

Figure 1

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.

Figure 2

BBC: Ben Nevis gets automatic weather station

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.

Possible Solution

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 collaborate with 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?

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*Station height
Addendum:- After a little investigation the prices for the Weatherhawk don’t look as expensive as they were a just a few years ago.

Recent Cairngorm observations

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.

Figure 2


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!

Figure 3 – Courtesy of Heriot-Watt University & Facebook

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.

First dusting of snow on Cairngorms

Figure 1

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).

Figure 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.

Figure 3 – © CairnGorm Mountain

Winter drawers on up the Zugspitze

The cold air ushered in by storm Xavier has certainly dropped the temperatures on the Zugspitze in the last 24 hours (fig 2). From a balmy max of 2.9°C yesterday, temperatures have quickly fallen away to around -9.1°C at 15 UTC this afternoon, but then again it is 9,718 feet up in the Wetterstein mountains in southern Germany close to the Austrian border. The strong northwesterly wind has died down a bit and they have had at least 20 cm of fresh snow during today, but how they manage to find any snow surface that’s not severely drifted to accurately measure a snow depth beats me.

Figure 2

BBC News: Bid to rescue Ben Nevis weather data

Figure 1 – Courtesy of the BBC

Believe it or not, the hourly weather observations from Ben Nevis from 1898-1902 have still not been digitised. It’s a real shame that the Met Office haven’t already done this on behalf of the nation, instead of relying on volunteers at Weather Rescue to do it for them (fig 2). But then again, they have their hands full, because they still have at least fifty years of climate records that the Victorians left them that also need digitising, because at the moment their climate records only extend back to 1910 for temperature and rainfall, and 1929 for sunshine. It’s not that the Met Office haven’t been round for all that length of time because they were established in 1854 as a small department within the Board of Trade by Vice-Admiral Robert FitzRoy, it’s just that when they did discover computers, they were too busy doing other things with them to bother adding the climate records that they held in the archives.

Figure 2 – Weather Rescue

Personally I think as much effort that’s gone into digitising these records, ought to be put into to reestablishing the Observatory on top of the Ben. Well not exactly Observatory such as the Victorians built, more an automatic weather station, similar to the one on top of Cairngorm. I realise that there’s already a SIESAWS on Aonach Mor just across the Coire Leis from Ben Nevis, but its lower (1130 M), and simply doesn’t have the prestige of being sited on top of the highest mountain in Britain gives it. Power to the AWS would obviously be the main problem, and an extension lead 4,411 feet in length would simply be out of the question. Solar panels may help a little, but they would ice up easily and disappear under rime for most of the winter. A large rack of lithium-ion batteries may do it, but who would pay for them to changed by helicopter every month. A small wind turbine might do it but that again would ice up, maybe eventually some kind of fuel cell might be the answer for these remote places.

This is what the directors of the Scottish Meteorological Society said about the closure of the Ben Nevis Observatory in 1904:

“It is to the Directors a matter of profound disappointment that in this wealthy country it should have been found impossible to obtain the comparatively small sum required to carry on a work of great scientific value and interest, and that they are now obliged to dispose of the Observatory buildings and dismiss the staff”

It seems that little has changed in the last hundred years or more since its closure.

So if you have an hour to spare, why not volunteer your time to help digitise the Ben Nevis observations? I’m sure it won’t be long before the Met Office, in these days of financial austerity, see the potential in this idea, and will open up their archived observational records to volunteers to be digitised too!

BBC: Ben Nevis snow free for first time in 11 years

Figure 1 – Courtesy of the BBC

Interesting news item from the BBC about the lingering snow patches in various gullies across the mountains of Scotland. I wonder if the three patches in the Cairngorms will survive? I suppose it will depend on the kind of Autumn that we are in for, cold and dry, or mild and wet. Just across the way from Ben Nevis is Aonach Mor with an AWS on it (WMO #03041). The AWS is not quite at the top of Aonach Mor which is 1221 M high (4,006 feet), but a little way down at the top of the chairlift at 1130 M (3,707 feet), from where I guess there is some kind of extension lead buried under the ground that connects the two. So temperatures should be not far off what they would be on the north face of the Ben, but of course that face would be in perpetual shadow.

Figure 2 – Courtesy of the backcorries blog

OGIMET wouldn’t let me download last Autumn’s data for the AWS on Aonach Mor, but here is the thermograph from the 4th of January through to April (fig 3), and as you can see although it was sub-zero for extensive periods, it wasn’t overly cold, and January was notably mild.

Figure 3

The rainfall anomalies for the period between November 2016 and March 2017 were generally near average, with November being a dry month (fig 4).

Figure 4 – November 2016 – March 2015 rainfall anomalies – Courtesy of the Met Office

The temperatures through the extended winter period where all above average, except for the dry November which was colder than average, December was exceptionally mild (fig 5).

Figure 5 – November 2016 – March 2015 temperature anomalies – Courtesy of the Met Office

Iain Cameron is correct when he says that the demise of the snow in the gullies of Ben Nevis was down to the lack of snow last winter. Snow is obviously dependent on rain falling with temperatures near or below freezing, and the lack of it was down to two things, colder periods also tended to be drier, and the wetter periods were also usually mild, a combination of the two meant that not enough snow fell to fill the gullies to survive through till the following Autumn.

I suppose if you coupled up the temperature from Aonach Mor with daily rainfall totals from Tulloch Bridge you could with a bit of jiggery-pokery estimate how much snow fell and accumulated at a 1000 M. With a few other bits of climate data you could also try to calculate how much snow was lost due to sunshine, evaporation, sublimation, and warm rain. It sounds like the job for a sophisticated NWP climate modelling tool as far as I can see.

Regional mountain forecasts from the Met Office

There have been some major improvements made to the regional mountain forecast issued by the Met Office which have just been announced. I’ve just had a quick look at them, and as a retired Munro bagger myself, I think that the website and it’s content are perfect for anyone planning to go hillwalking  and trying to assess just how good or bad weather conditions will be.

Figure 1 – Courtesy of the Met Office

Thankfully, although the webteam use the same map component they use in the severe weather warnings (fig 1), it’s not zoomable, just clickable, and when you do click it you get quite a detailed forecast (fig 2). I imagine that in winter each regional area forecast will also include any warnings regarding avalanche risk. There, who said I couldn’t write anything nice about the Met Office!

Figure 2 – Courtesy of the Met Office

The shelter of mountains

Figure 1

An interesting number of examples of just how shelter from mountains can make the difference between a cloudy day and one with sparkling spring sunshine in today’s visible satellite sequence. There are clear skies evident in the air coming south southwestward from over the mountains of Norway and into the northern North Sea. There’s also shelter as the air is warmed and dried on the southern slope of the Grampians over Perthshire and Fife. The mountain and fells of the northern Lake district are doing enough to stop the passage of the SC sheet extending southwards from the Scottish Borders, and the Pennines are just high enough, and the gradient is just backed enough to keep the same SC sheet from invading Lancashire, as it’s done east of the Pennines in Yorkshire.

The Cuillins are calling

Figure 1 – In the days before the bridge

Most years in spring you always seem to find a spell of anticyclonic easterlies over Scotland, and the Cuillins in Skye start calling to any intrepid Munro bagger out there. This year has been no exception with the weather since the 1st of May being absolutely glorious in the Northwest Highlands for the Munroist, as these visible satellite images reveal (fig 2). It’s been well over twenty years since I’ve been on Skye but one day I will return, if I’m not too old, and try to finish what I started, that’s if my wife will let me.

Figure 2 – Courtesy of the Met Office and EUMETSAT