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.

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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

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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.

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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!

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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.

13 September 2016 – Heat

The 13th of September 2016 apart from being our wedding anniversary, was quite an exceptional day temperature wise across a lot of  western Europe and eastern England. I always apply my own home grown rules when looking at maximum temperature anomalies.

  • -1 to +1 Near average
  • +1 to +4 Warm (or mild depending on the season)
  • +4 to +8 Very Warm (or exceptionally mild)
  • +8 – +12 Hot
  • >+12 Very Hot

The 13th was hot in a large area from the southeast way up to the northeast of England. There were some coastal exceptions but generally inland anomalies were above +10°C and in the top five SYNOP stations maximum anomalies exceeded +12°C.

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Maximum temperature anomalies 06-18 UTC on Tuesday 13 September 2016

Here is the ranked list of hottest places. The highest 34.4°C occurred at Gravesend and made it the warmest September day since the infamous 35.6°C at Bawtry in 1906, there is some talk regarding its validity, but I’ll have a more detailed look at the observations from their in another article.  I remember Bawtry well because it was there I had my initial interview with the Met Office in June 1970.

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Meanwhile in the more western parts thundery showers were tacking south north producing some severe thunderstorms and heavy rain, but more about that in another article – so much to do and so little time.

August Temperatures

Air Temperature Anomalies 01 Aug to 31 Aug 2016
Air Temperature Anomalies 01 Aug to 31 Aug 2016

I must admit that I never realised just how warm it had been over central Russia in August, a monthly anomaly of +8°C is something quite special. Other than that their were negative temperature anomalies over the Balkans (-2), Scandinavia (-1), North Africa (-1)  and of course the central Atlantic(-1).

Summer 2016 – best in East Anglia worst in Scotland

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I have just downloaded the gridded 1910 data series from the Met Office for August so that I can have a look at the 2016 summer index across the country. I require that sunshine, rainfall and temperature gridded data so I can calculate the monthly terciles and quintiles values that are used to calculate the summer index. The summer is of course the meteorological summer and consists of the months June, July and August. The table below is the summer index for the whole of the UK, and as you can see summer 2016 index was +10 which is above average and much better than last year, but comes only joint 19th best since 1929.

UK Summer [JJA] Index 1929 - 2016
UK Summer [JJA] Index 1929 – 2016

The picture is much better when you look at the regional summer indices that I’ve also calculated and ranked. East Anglia comes top with an index of +25 just ahead of southern England with +20. Incidentally, in East Anglia summer 2016 was also the best summer index since 1995. No region in Scotland fared particularly well this summer with summer indices of around average (remember the best summer scores 48 and the worst summer -48 using the summer index formulae). You can find more details about the summer index in an earlier article I wrote earlier this year.

Best Summer Index [JJA] in 2016
Best Summer Index [JJA] in 2016

Warmest Summer since 2006 in Central England

Daily CET Summer [JJA] 2016
Daily CET Summer [JJA] 2016

It looks like Summer 2016 was the warmest in Central England since 2006 with a mean temperature of 16.43°C which was +1.08°C above the long-term average (1961-1990). Surprisingly no maximum records were broken during the summer but two high minima were.

Warmest Summers 1659-2016
Warmest Summers 1659-2016

In the bigger scheme of things Summer 2016 was the joint 27th warmest since 1659 based on mean temperature.

Summer mean CET & anomaly 1659 - 2016
Summer mean CET & anomaly 1659 – 2016

 

Hottest days since 1878

Daily Central England Temperatures

For a bit of fun I thought that I would graph the hottest days in the daily Central England Temperature [CET] series since 1878. My graph is a copy of one that I saw on the Met Office web site, so it’s not particularly unique. As you can see the hottest day in Central England is tied between the 3 August 1990 and the 3rd July 1976 with a composite maximum of 33.2°C. The colour of the bars indicate that seven of the top fifty warmest days have occurred since 2001, in fact last month’s maximum of 30.9°C (19 July 2016) has now become the 22nd hottest day in the last 138 years.

I’m not that satisfied with the graph though as it fails to highlight clearly in which twenty year period the extreme occurred, even though I’ve added a colour code for each bar that corresponds to the specific twenty year period that it occurred. It maybe the colours that I’ve chosen are wrong, but it might also be the fact there is very little difference between each extreme record. I also realise that the sort needs to be a little more sophisticated, so that records with equal maximum temperatures are also sorted a second time on their means so that the day with the higher mean is also ranked higher. So I may revisit this application to fix both that and also to add extra functionality to filter on warmest day by month and season, as well as year.

Palm Spring hottest as heatwave continues in United States

Palm Springs
Looking down at Palm Springs

Not just quite as hot at Phoenix as it was yesterday because it only made it to 115°F! Apparently the temperatures reached 122°F at Palm Springs yesterday which was one degree short of all time high of 123°F set in 1995. The above picture is one I took looking down from the Palm Springs Aerial Tramway at the eastern side of the city when we their back in September 2008, it was over 100°F then so 120°F+ must be sizzling! The best time to be out and about in Palm Springs was 6AM in the morning and heading for a diner for a breakfast of fresh orange juice and pancakes. If I lived there I think I would regularly take the tramway to 8,500 feet in the summer because it’s so refreshingly cool up there, in fact I would be sorely tempted to take a tent and stay up there till Autumn.

Max temp reported at 00 UTC on 21 June 2016