Sunniest place in Europe – 18 April 2018

The sunniest places in Europe yesterday* were to be found on top of mountains, such as the Sonnblick Observatory on mount Hoher Sonnblick in the Austrian Alps and the Zugspitze Observatory in the Wetterstein Mountains in Germany (fig 1).

Figure 1

* This is only the sunniest of the places that report sunshine in their SYNOP. For some reason most of Scandinavia don’t or won’t, the Netherlands and Belgium do report sunshine, but I think they include it in their midnight observations rather than at the more conventional 06 UTC the next day. I should imagine that the sunshine totals north of the Arctic Circle on a cloudless day in summer are 24.0 hours, speaking of which…

Sunshine in Tromso
Figure 2 – Courtesy of Wikipedia

Here are the climate statistics for Tromso in northern Norway courtesy of Wikipedia (fig 2) which makes interesting reading (crampons when you’re out shopping on the High street and no frost in June since 1997). Having the advantage of sunshine 24 hours a day in summer I would have thought that the average of 221 hours for the month of June would have been a lot higher. Apparently the sunniest month in Norway was in July 1980 when Tromso recorded 430 hours of sunshine. It’s interesting to see the zero hours of sun for the month of December, there can’t be too many weather stations in the world were the average is in fact a constant like this. I still can’t see why across northern Norway the maximum possible sunshine total for June can’t approach 720 hours (30 x 24)? I suppose it’s back to the question of what constitutes ‘bright’ sunshine I raised in the last blog. All I can imagine is that even when the sky is cloudless, the sun when it’s low on an Arctic summer’s night just isn’t strong enough for maybe four or five hours or so to exceed the threshold set for ‘bright’ sunshine.

The missing sunshine

UK Sunshine card

These are the hourly sunshine totals for yesterday across the UK (fig 1). As you can see Shoeburyness was marginally the sunniest place with 13.0 hours, but many place across southern areas were close to 100% of the maximum possible. Places like Shoeburyness with the sun rising over the North Sea in the east, and setting over a flat Essex to the west must have a slight advantage over places like Exeter for example, where the sun is slightly blocked by the Blackdown hills to the east and by Dartmoor to the west, which may shave off 0.2 hours on a cloudless day.

Figure 1
Missing Sunshine

Interestingly in my application I made the 13.0 hours at Shoeburyness only 92.2% of the theoretical maximum. Checking on the timeanddate.com website tells me that the day length at Shoeburyness was 14:07:30 for yesterday, so the 13.0 hours of reported sunshine was indeed only 92.0% of the total possible, so the algorithm I use is quite accurate. But what happened to the missing 1:07:30 seconds of sunshine? The total day length would of course start when the top limb of the sun first appeared over the horizon until it disappeared below the horizon in the west, this process may account for 15 minutes or so, but I can’t imagine haze in the atmosphere making up for remaining 0:52:30 on a cloudless day with good visibility like yesterday (fig 2). Who knows perhaps there was some thicker cirrus that went undetected by the LCBR, or maybe we have the threshold for bright sunshine set too high these days, in order to mimic the totals we used to get from the old Campbell-Stokes recorders?

Figure 2 – Shoeburyness
Adding hourly totals works

Reassuringly, as long as you collect all the hourly SYNOP observations, then adding the hourly sunshine totals does produce a figure that’s very close to the one reported at 06 UTC the next day (fig 3).

Figure 3

Places where I’ve work and seen close – RAF Binbrook

Figure 1

I spent four good years at RAF Binbrook on the Lincolnshire wolds between 1983 and 1987 as an observer before being posted to RAF Kinloss. I knew the Lightning (fig 1) was to be withdrawn from service and the based closed the next year. So whilst on duty at Kinloss I always kept a close eye on the observations from WMO station 388 just to see if the inevitable had happened, and on the 1st of July 1988, almost 30 years ago now, it duly did.

Figure 2

As far I know the last observation at 15 UTC was completed by Haydn Morris with his usual aplomb, complete with a couple of extra 9 groups as you can see (fig 2). I’ve never worked at any station that was so prone to low stratus at 100 feet or less from any direction in just about any airmass, and so it seems to be rather fitting that one okta at 500 feet featured in the last observation!

Figure 3 – Courtesy of Google Maps

They have made a good job of tearing up all the runways and knocking down the control tower since I left, in fact you would hardly know that there was once a 7,500 foot runway there at all, but they do seem to have left behind an old Lightning just for old times sake (fig 3), though it would have a job taking off these days if a QRA alert was called.

It’s nice to see the F6 Lightning making a final appearance in a collection of commemorative stamps for the 100th anniversary of the Royal Air Force (fig 4). That runway that features in the stamp isn’t the ones at RAF Binbrook, the main ones there being 210/030° and not 190°, neither is it the main runway at RAF Wattisham, another Lightning base, so therein lies a bit of a mystery.

Figure 4 – Courtesy of the Post Office

The snowfall of February and March 2018

I thought that I would take a retrospective look back (excuse the tautology) at the last two cold snaps that we’ve had, and some of the snow depths that were reported by various AWS around the country. The graphs show accumulated and fresh snow depths that I’ve gleaned from SYNOP reports which in the UK helpfully include hourly snow depths (NWS please take note). The blue bar chart in the graph represents fresh snow, that is the difference in snow depth between each hour, red bars indicate snow melt, and the light blue bar series is the hourly snow depth. Bars that span more than an hour are because I’m missing those observations.

From the recent cold spell that started last weekend (17th March) I’ve included the chart for Dunkeswell in Devon (fig 1) and High Wycombe in Buckinghamshire (fig 2).

Figure 1

As you can see the snow on the higher ground of Devon (Dunkeswell 252 m amsl) will do well to survive much longer than four days, all though the deeper drifts on the moors will last longer. You can see why the heavy snow on the morning of the 18th at High Wycombe caught the Met Office out, with the bulk of the 27 cm falling in just two hours (fig 2).

Figure 2

Here are three charts from the much longer and severe cold spell that started at the end of February 2018:

Figure 3

The snow came quite late to St Athan in south Wales (fig 3), but when it did come overnight on the 1st and 2nd of March, it did it in style and put down 56 cm before it had finished. That amount of snow took a whole week before it thawed away completely.

Figure 4

The snow at Wittering in Cambrigeshire started on the evening of the 26th and came in a couple of batches, with a maximum depth of 37 cm by the 3rd of March (fig 4).


Scotland also had a lot of snow, as these next two graphs testify. The first is from Bishopton in Glasgow, where a maximum depth of 46 cm was reached on the morning of the 2nd of March (fig 5).

Figure 5

Finally here’s the snow graph for Drumalbin a weather station on a low hill in south Lanarkshire, where 55 cm or more of snow had accumulated by the 1st of March (fig 6).

Figure 6

I’m sure these laser measured snow depths are very accurate, but in both snow events the wind was strong and there was a lot of severe drifting going on, so how representative these depths are is open to question.

The trouble with automatic weather stations in cold weather

Figure 1 – Courtesy of the Met Office and Weather for Schools

Automatic weather stations now make up nearly all the network of observing sites in the UK, and they all have an inerrant problem when it comes to reporting precipitation totals in very cold weather, and that is they can’t!

Precipitation from AWS

Have a look at the 12 hourly totals [18-06] from 06 UTC this morning from across the country (fig 2) and you’ll see that almost all stations are reporting no more than a ‘trace’ of precipitation. These accumulations are obviously incorrect because most of the precipitation that’s fallen in the form of snow will still be stuck, frozen in the funnel of the gauge. Some AWS sites do have snow depth sensors, but these are not the answer, and can be easily fooled as we have seen this winter, by drifting when the wind is strong enough to lift any snow that has fallen.

Figure 2
Weather Radar

Here’s are my estimates from the radar network of the precipitation that has fallen since 06 UTC on Saturday morning (fig 3). If this is anything to go by then, the deepest of the snow looks to have fallen across Norfolk and Suffolk in some kind of convergence zone, with precipitation totals as high as 16-24 mm. I estimate that there was around 6.9 mm from around High Wycombe, which I realise is not enough to account for the 27 cm of snow there at the moment. In my defence I offer the “spoking” that’s evident from the Chenies radar. Chenies lies not so many miles E’NE of High Wycombe, and I did speculate last year that the “spoking” that occurs there at times is caused by the radar being blocked by some of the large trees that surround the site.

Figure 3
One solution

I don’t know enough about why this is such a problem in the 21st century, you would have thought that it would be easy enough to detect when temperatures are close or below freezing and turn on heating elements inside the gauge to melt any snow that it catches. For all I know this might be already happening, because the SYNOP format is not how AWS report their readings these days, and much more detailed one minute or even more frequent observations from all the sensors are being taken and transmitted back to Exeter, which may include the water equivalent of any snow that has fallen, who knows…

A bit too windy?

Figure 1

I’ve been monitoring the wind speeds from the Cairngorm SIESAWS this week where it’s been extremely windy. As you can see from the plotted observations for the last few days (fig 1), winds peaked at 15 UTC on the 15th of March, with a mean speed of 86 knots (99 mph) and gusts to 110 knots (126 mph), although mean speeds have never fallen below Beaufort force 10 in all that time. I’m beginning to think that they might have sensor problems up there at the moment, I know for the last few months reported wind speeds have been too low, but now they look like they could be too high.

There is a way to check if the wind speeds are too high though, because there is a second AWS on Cairngorm run by the Heriot-Watt Physics department (fig 2).

Figure 2

Even their sensors (the one’s that pop-up out of a can twice an hour) are also looking a bit suspect. The wind direction is definitely wrong, possibly because of a massive build up of rime in these condition. Wind speeds look too low at first, then went missing, and now look similar to the ones being reported by the Met Office SIESAWS.

Winds as severe as this are perfectly possible of course on Cairngorm, which makes it doubly difficult in deciding if they are right or wrong.

Recent high temperatures at the North Pole

Figure 1

Apparently the air temperature at the North Pole rose above freezing yesterday (25 Feb 2018). This winter, like many more before it in recent years, the temperatures in the Arctic has been exceptionally mild, at times anomalies have been more than 25°C higher than the long-term average. This is the thermograph for the North Pole up to the 23rd of February from NCEP reanalysis data (fig 1).

This is well supported by the observational data from Cape Morris Jesup, the most northerly point of mainland Greenland at 83°37″N and just 442 miles from the pole itself (fig 2). For a short while on February 25th the temperature there reached 4.7°C at 09 UTC, but by 18 UTC that evening the temperature was back down to -13.2°C.

Figure 2

This is the best aerial shot of the weather station at Cape Morris Jesup that I can find on the internet of what must be the bleakest and most isolated spot in the whole northern hemisphere (fig 3).

Figure 3 © System Operator Kim B. Svensson of the Royal Danish Air Force

It’s quite bizarre that for a while yesterday it might have been colder down here in Devon just for a few hours, than it is was in the high Arctic. It’s probably another symptom of the recent SSW event in the high atmosphere, and of course the underlying warming that’s been going on in recent years. Temperatures today across the Arctic seem to be returning closer to what constitutes normal for up there at the moment, as the milder tongue of air that caused all those record high temperatures is squeezed out by colder air (fig 4).

Figure 4 – Courtesy of EarthWindMap

Puts our 1 to 3 centimetres of snow into perspective

Figure 1

The heavy snowfalls of the last couple of days over western Russia and central Asia have put our overnight warning for of just 1 to 3 centimetres into perspective. The above chart are the reported snowfall depths at 06 UTC this morning overlaid with contoured MSLP (fig 1). As you can see from the inset table one of the observing stations close to Moscow (WMO #27612 Dolgoprudny) is reporting 53 cm of level snow (~21″). Dolgoprudny, I’m reliably informed by Wikipedia, lies 20 km north of the city of Moscow.

Russia has a terrific SYNOP observing network, but they only report a snow depth once a day, and for some strange reason, probably to do with time zones, eastern Russia report it at 03 UTC, and western Russia stations at 06 UTC. Without some kind of bespoke SYNOP snowfall application that scans all observations for the latest reported snow depth in all observation for a selected day (now there’s an idea), I can’t extend the chart any further eastward.

The mystery of the Dalwhinnie AWS solved!

Figure 1 – Courtesy of Google Maps

Thanks to some old colleagues I’ve now solved the mystery of exactly where the AWS is at Dalwhinnie. Believe it or not, it’s in the grounds of the distillery, which must be a first for the location of any weather station I would have thought (fig 1). Perhaps the Met Office could approach the likes of Glenlivet, Tomatin and other distilleries across Scotland to host a network of AWS? Then again it might end up with a disproportionate number of them being located in Morayshire, and we already have Kinloss and Lossiemouth (fig 2).

Figure 2 – Courtesy of maltmadness.com

Looking at an aerial view of precisely where the AWS is located at Dalwhinnie, I don’t think it makes an ideal location for a climate station, being surrounded as it is by so much tarmac, buildings and warehousing (fig 3), none the less it didn’t stop it getting down to -13.5°C on the 21st of January.

Figure 3 – Courtesy of Bing Maps

The exact location of the AWS with respect to the buildings could explain some of the spikiness in the thermograph trace during the evening of the 20th (fig 4), but without an anemograph, which I don’t think it has (not that we could access the data even if it had), it’s impossible to say if the nearby buildings had anything to do with it. So it’s no wonder that Braemar on the other side of the Cairngorms, with a little more shelter, and without a distillery on the doorstep pipped it to being coldest.

Figure 4 –  Courtesy of www.weathercast.co.uk

The other thing about distilleries is that like breweries, they can push out huge clouds of steam when they are mashing (I’m guessing at what the precise technical term is here), not that I think this would affect the sensors but if I remember it’s quite a pong!

I always had trouble getting an ice bulb going…

Figure 1 – Courtesy of Twitter

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.

Figure 2

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).

Figure 3 – Courtesy of OpenStreetMap

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!

Figure 4

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).

Figure 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)?

Figure 6 – 2 February 2018 – courtesy of NASA Worldview.