April 2017 – Weather World

Figure 1 – Courtesy of Armagh Observatory

I’ve just watched another interesting installment of Weather World on the BBC and noticed from the credits that it was written by Nick Miller. He and Sarah Keith-Lucas hosted the proceedings that were centred at a number of locations in Northern Ireland:

  • Belfast International Airport – Aldergrove to you and me, and saw why weather is so important for aviation at airports.
  • Ulster Aviation Society Museum – where they looked at the history of ‘weather flights’ across the Atlantic.
  • Armagh Observatory – and saw how observations are made today, and at their long running climate recordings, which started on the 27th of December 1794.

I’ve changed some sunshine cards in my time at a number of stations across the UK, some of the locations that the recorder was sited were far from ideal, but the observatory at Armagh as a novel approach to getting around the problems of trees getting in the way, the sunshine recorder sits in a lift like device that raises and lowers the old Campbell-Stokes sunshine recorder what looks like 50 foot into the air (fig 1), I hope after that platform doesn’t affect the wind speeds that they measure from the anemometer up there though. They take their weather observations very seriously at Armagh!

At a 24 hour station you could always change the sunshine card late in the evening, it seems strange to see it being changed at 09 UTC in the morning, there were times that someone forgot to change the card, or on very wet days the card almost disintegrated because it was so wet.  Seagulls also liked to attack the cards for some reason, and then there was the perilous job of checking the previous shift’s sunshine card, was that a continuous burn or not, and just when did you start or stop measuring the trace at sunrise and sunset?

I like Sean Kelly the weather observer at Armagh, he’s been doing the job for the last 18 years, and seems to have the right attitude to technology, they’ve tried automatic weather stations in the past, but found that they weren’t reliable enough. That’s what we said in the Met Office for over 30 years, we had a good run for our money but in the end we were replaced by an AWS, try getting a job as a weather observer at the Jobcentre now, Sean might well be one of the last one of us left here in the UK. Nick explained about how observations are taken each morning at 9 o’clock, “this weather ritual that has been happening for over 200 years” he said, except for last Tuesday when it looks like they had a day off (fig 2).

Figure 2 – Courtesy of the BBC

Given the brief from the producer, and the time constraints of the program, Nick Miller did a pretty good job in getting his story across, Sarah Keith-Lucas came across as a really nice person that I’m sure she is. Interestingly they kept it to just the two of them, and wisely in my opinion, didn’t include any input from the ubiquitous Carol Kirkwood. It’s possible that the BBC have decided to use Nick Miller for these kind of programs in favour of John Hammond from now on, and maybe that’s the reason why he decided to take an early shower.

13 September 2016 – Gravesend

Gravesend - Broadness (courtesy of Tallbloke.com)

Gravesend – Broadness (courtesy of Tallbloke.com)

The maximum temperature at this time in September usually occurs around 13 UTC or possible 14 UTC. The hottest place in the SYNOP observations in the UK on the 13 September 2016 was at Gravesend. Its maximum temperature of 34.4°C made it the warmest September day since 1911. Here’s a snippet from the Monthly Weather Report for September 1911 (courtesy of the Met Office) about that warm spell. Since 94°F is 34.444°C so the Gravesend reading just falls short.

capture1

The thermograph based on hourly SYNOP data was quite peculiar. The temperature instead of peaking at 13 or 14 UTC as you might have expected on such a hot day just plateaued.

thermograph-for-03784-gravesend-broadness-00-utc-on-13-sep-18-utc-on-14-sep-2016

The temperature hit 32.0°C at 1300 UTC and again at 1600 UTC, but between those times (at 1400 and 1500 UTC) it dropped slightly and levelled off at 31.4°C. In that time period the temperature must have peaked to produce the 34.4°C maximum, so it must have climbed and fallen by at least 2.4°C in the space of an hour. It certainly can fall and rise very quickly at Gravesend because in the morning it rose 4.7°C in an hour (between 09 and 10 UTC) and later it fell 6.5°C in an hour (between 17 and 18 UTC). I would have said that the latter may have been down to a sea breeze, but there had been a light flow from the east for most of the day which confuses matters. The one minute data that the Met Office collect from Automatic Weather Stations like the one at Gravesend would clarify matters, but I doubt that this data would ever be released.

synop-grid-03784-gravesend-broadness

03784 Gravesend Broadness 13 Sep 0600 UTC – 14 Sep 1600 UTC

A similar hiatus in temperature occurred at Heathrow that day too, at 1200 UTC the temperature was 32.1°C but by 1300 UTC instead of being a little higher at 1300 UTC it had fallen by 2.2°C to 29.9°C. The temperature recovered a little by 14 UTC and recovered again at 15 UTC to reach 31.8°C. Somewhere between these times a maximum of 32.8°C occurred.

thermograph-for-03772-london-heathrow-00-utc-on-13-sep-18-utc-on-14-sep-2016

synop-grid-03772-london-heathrow

03772 London Heathrow 13 Sep 0000 UTC – 14 Sep 1800 UTC

A drop in temperature at either 1300 or 1400 UTC on the 13th is also noticeable at a lot of other sites across the southeast, I suppose it could have been caused by some medium or thick high level cloud, but there certainly was little evidence of it as far as I can see from the visible satellite images apart from a okta or two of cirrus or medium level castellanus.

uk-5-2016-09-13-1300

Visible Satellite Image  13 Sep 2016 1300 UTC (courtesy of the Met Office & EUMETSAT)

As far as I can deduce this is the location of the meteorological enclosure and Stevenson screen at Gravesend, and yes that it is some kind of communications mast next to it!

03786-gravesend

And here is a zoomed out view of its location with a little more perspective of where it lies, east of the city of London on the south bank of the Thames which of course is tidal – but I don’t intent to dig around for those details! If you are interested the Talkbloke blog has an interesting article about the location of  the site.

03786-gravesend

In conclusion all I can say given its location is that Gravesend seems a most unlikely place for a hot spot. Why higher temperatures were not recorded at places relatively nearby like Heathrow, Northolt or St James Park on a day when there’s a light flow from the east and sitting as it does jutting out into the Thames with the open sea no more than twenty miles to the east beats me, perhaps it’s all down to its proximity to mainland Europe. The 13th of September was not a one-off, Gravesend is a well-known hot spot and has done it before and come under scrutiny, and now it ‘s done it yet again.

Often forgotten

The northern Isles are very often forgotten in weather forecasts on the media, and often weather there is much better than it is further south on the mainland, and that’s been true in recent weeks with some lovely sunny days in the Shetland Isles. Here are the daily sunshine totals and accumulations for the last month from Lerwick.

Sunshine at 03005 Lerwick - United Kingdom 82 AMSL [13 May - 13 June 2016]

Sunshine at Lerwick  [13 May – 13 June 2016]

As you can see over the last month there has been well over 200 hours of sunshine and four days had totals of over 15 hours, because that’s the other thing this time of year in the northern Isles, the days are very long and the nights short. The sunrises at Lerwick at around 3:39 AM and doesn’t set till around 22:34 PM in mid June, which gives a day length of almost 19 hours. Mind you it never gets desperately warm up there thanks to the cold seas that surround the islands, here are the hourly temperatures from the last week.

03005 Lerwick - United Kingdom 82 AMSL 6 June-12 June 2016

Temperature, dew point and humidity at Lerwick 6 June-12 June 2016

Weather impacts on Queensferry crossing

Forth road bridges new and old (courtesy of Scottish government)

Forth road bridges new and old (courtesy of Scottish government)

I was intrigued to hear that the opening of the Queensferry crossing had been delayed for five months by high winds in April and May this year. I’m not going to get into the politics of the whole thing on how delays during just two months can set the whole project back five months defies any sensible kind of logic, but I won’t dwell on that side of things.

Forth Replacement Crossing (courtesy of Wikipedia)

Forth Replacement Crossing (courtesy of Wikipedia)

The weather station at Gogarbank

I am sure that there are any number of wind vanes and anemometers affixed to the bridge and the cranes that are helping build the bridge, but I am not privy to that data, or the anemograph traces that they produced during April and May of 2016, so all that I can do is look for the closest SYNOP station reporting hourly wind speeds and that happens to be from Gogarbank in Edinburgh, in fact if you look at the map below, Gogarbank is remarkably only just over 5 miles to the SE of south Queensferry.

Queensferry - Gogarbank (courtesy of Google maps)

Queensferry – Gogarbank (courtesy of Google maps)

Gogarbank is a strange location to site a new weather station because it looks like a lot of money has been spent setting up a duplicate station to the one that must have existed for many years at Edinburgh airport. It’s an estimated WMO class 4 site as far as temperatures are concerned, but must be more representative of temperatures that the airport was. I won’t go into the obvious question of why the Met Office duplicated all the sensors at Edinburgh airport with a new site just 1.7 miles to its S’SE – perhaps they plan to do the same at other airports around the UK such as Heathrow? Gogarbank is 57 metres above sea level and looks well exposed to most directions.

Edinburgh airport and Gogarbank

Edinburgh airport and Gogarbank (courtesy of Google)

03166 - Edinburgh Gogarbank

03166 – Edinburgh Gogarbank (courtesy of Google)

Below is a graphic showing how wind speed increases with height, and as you can see a 16 MPH surface wind would equate to a wind of over 30 MPH at crane height of 200 metres (x 1.875) . The safe working limits are between 25 and 31 MPH, so using the winds from Gogarbank we are looking at surface winds of no more than 13 to 17 MPH, either as a mean speed or in any gusts. I’m not going to try adjust the winds for height, but obviously they must be a little higher at Gogarbank than places closer to the Forth, but how do you factor in winds that are blowing off an estuary rather than over farmland and allow for all the added friction?

Forth wind speed profile (courtesy of Scottish government)

Forth wind speed profile (courtesy of Scottish government)

Weather impacts on the Queensferry crossing

Weather impacts on the Queensferry crossing

Above is what the Forth Crossing Bridge Constructors [FCBC] have said about the delays caused by the wind and weather during April and May of 2016. And below is the anemograph trace from hourly SYNOP data that I’ve put together for the two months in question. Just note that the anemographs show wind speeds in knots and not MPH, so the limits using these graphs are roughly 11 to 15 knots, which is just a little bit less than Beaufort force five.

Winds in April 2016

03166 Edinburgh Gogarbank - United Kingdom 57 AMSL 1 April-30 April 2016

03166 Edinburgh Gogarbank – United Kingdom 57 AMSL 1 April-30 April 2016

April was I would have thought a very typical month with winds generally from the west but with easterlies for short spells (but not exclusively) between the 2nd-4th, 10th-15th, 21st and the 23rd. At a quick glance I would have thought that the 1st, 6th, 11th-12th, 17th-18th, 25th-26th, and the 29th would have been out of limits, at total of around 9 days.

Winds in May 2016

03166 Edinburgh Gogarbank - United Kingdom 57 AMSL 1 May-31 May 2016

03166 Edinburgh Gogarbank – United Kingdom 57 AMSL 1 May-31 May 2016

In May there were prolonged spells of easterlies between the 6th-14th and the 23rd-31st. I should imagine an easterly and the longer sea fetch may have caused then more problems than other directions, but I could be wrong. Wind speed were out of limits at a guess for the 1st-5th, 7th, 11-12th and the 19th-21st, a total of 10 days by my rough and ready reckoning.

In conclusion

So my figures are for 9 and 10 days out of limits are a little lower than FCBC’s 13 and 12 days, a little lower but no real conspiracy theory. Reasons for the differences are the fact that my wind speed data is for a site 5 miles to the S’SE and over land and not water, and of course the fact that I don’t have to worry about anyone’s life when I do my guessing. All that I can say is with these low limits, is that they have done a pretty good job of building a fantastic bridge with 35,000 tonnes of steel and 150,000 tonnes of concrete in the timescales that they’ve achieved, I can’t wait to drive over it in the future.

Recent sunshine totals

Daily sunshine 24 May - 6 June 2016

Daily sunshine 24 May – 6 June 2016

Excuse the rant

I saw one of the BBC forecasters today show some sunshine statistics for the UK and the stark difference between the totals from the east and the west. That got me to thinking that I’ve never really done very much with sunshine stats from SYNOP observations, so I set myself a little task to knock up an application to do just that this afternoon. <rant>The reason why I haven’t done it before is probably due to the lack of sunshine reporting stations in the UK which are released by the Met Office! It might have its headquarters in Devon, but there is just one sunshine reporting station in the whole of Cornwall and Devon, have a look at the coverage in France and Germany and see the difference. There are many climatological stations out there that the Met Office are just never going to release the data for – this side of hell freezing over – which I think is a very great shame, in fact it’s worse than that, it’s a scandal, after all it’s our – the public of this country’s – data. My plea to the Met Office is to please release as much climatological data as you can, you might not want to do much with it, but I certainly can. The sad thing is that I wouldn’t even be able to process this data and present you with these maps, charts and tables if it wasn’t for a Spanish web site, if I depended on the Met Office I would have no observational SYNOP data, they would rather just sit on it </rant>.

The sunshine data

Anyway getting down from my soapbox and back to the sunshine totals from the last two weeks, below is a tabulated ranked list of the 52 sites across the UK, and as you can see Tiree tops the list with over 170 hours in 14 days, or 12.2 hours per day and 72.6 of the theoretical maximum available – if my astronomical functions are working correctly. Bottom of the list is poor old Leconfield on Humberside with just 21.3 hours in the two weeks, or just over 20% of the possible maximum. Having said that there are a great many cloudy stations at the bottom of the list, and all in the east of the country, all in all a very interesting spell of weather. Most of the southern and central European countries support the reporting of daily sunshine data in their SYNOP/BufR observations. The trick is because of the various time zones across Europe there are some countries that report sunshine at midnight rather than 06 UTC, so I still have some work to do for the more eastern countries to get the maximum coverage.

Daily Bright Sunshine 24 May 2016 - 6 June 2016

Daily Bright Sunshine 24 May 2016 – 6 June 2016

Spotlight on Lusa

The weather station with the WMO designator 03037 has been in the news a lot this week. The station is situated on Lusa on the Isle of Skye, and I thought that I’d just look in a bit more detail at it. Here’s the big picture of where you can find Lusa.

03037 - Lusa (Skye) courtesy of Google Maps.

courtesy of Google Maps.

And here it is in a bit more detail…

03037 - Lusa (Skye)

courtesy of Google Maps.

The blue circle marks a 30 metre radius from the enclosure so this site could be just far enough way to be classified as class 1, but why the Met Office couldn’t have sited just up the road at the Broadford airstrip beats me, but there is obviously a very good reason why not. It’s probably called Lusa because of a small collection of houses close by, and the fact that it lies close to the little bay of Ob Lusa, which if you Google it will find is where you can find cold water coral (never say this site is just all about boring weather), I guess that Ob is Gaelic for bay.

Lusa (courtesy of Ordnance Survey and Bing Maps)

Lusa (courtesy of Ordnance Survey and Bing Maps)

It’s easy to see why this week in the easterly flow this site has been the warmest in the UK on at least two consecutive days, not only because of its location on the west coast of Scotland, but also because its downwind of the Northwest Highlands and the Kylerhea hills (just a few kilometres to the ESE), of which the largest is Sgùrr na Coinnich (739 metres). Interesting Glen Arroch lies to the southeast of Lusa which probably defines the predominant wind for the station. Anyway here’s the thermograph of hourly temperatures for the last two weeks for Lusa. On the 9th of May the 06-18 maximum was 26.7°C and yesterday (the 10th)  it was 25.6°C.

03037 Lusa (Skye) 18 AMSL 27 April-10 May 2016

03037 Lusa (Skye) 18 AMSL 27 April-10 May 2016

The wind, as you can see from the plotted hourly observations for the last few days, was crucial. At times the E’NE flow did veer a little more to the NE, and brought a reduction in the temperature, but for most of the time the gradient was strong enough to keep the sea breeze at bay and maintain a strong easterly component.

03037 Lusa (Skye) [08 May 2016 - 11 May 2016]

03037 Lusa (Skye) [08 May 2016 – 11 May 2016]

It’s interesting to note that in the cold spell, which occurred less than two weeks ago, there was a good snow cover on a lot of the western isles including Skye. You can see that the automatic weather station was having a bit of deciding on the exact weather type during the 28th of April. I cannot doubt that with these temperatures there was a fair amount of wet snow around on the morning of the 28th of April.

03037 Lusa (Skye) [27 Apr 2016 - 01 May 2016]

03037 Lusa (Skye) [27 Apr 2016 – 01 May 2016]

If it could snow on the island of Tiree I’m sure it did the same on a coastal site in Skye. Have a look at the following image and observations from Tiree, it’s not that unusual an occurrence but not that common in recent years.

Tiree on the morning of 28 April 2016 (courtesy of lifeontiree.wordpress.com)

Tiree on the morning of 28 April 2016 (courtesy of lifeontiree.wordpress.com)

03100 Tiree [27 Apr 2016 - 01 May 2016]

03100 Tiree [27 Apr 2016 – 01 May 2016]

And finally here are a couple of plotted charts to compare the contrast between the 28th of April and recent days.

Synops for Thu, 28 Apr 2016 at 0600 UTC

Synops for Thu, 28 Apr 2016 at 0600 UTC

Synops for Mon, 9 May 2016 at 1200 UTC

Synops for Mon, 9 May 2016 at 1200 UTC