Days of thunder

[xmetman]

It’s very difficult, I would say impossible to find the latest detailed statistics on thunder across the UK, let alone across Europe and other parts of the world. The obvious answer would be to generate monthly frequency maps from the output of the Blitzortung lightning system, but I am not a member, and even if I were it may still not be possible to get my hands on the data to do this with. Despite all this, I have come up with a simple and very effective method of compiling ‘days of thunder’ from SYNOP observations. It depends on the present weather code [WW] and the past weather codes [six hourly ww1 & ww2 code from the main synoptic hours] and the fact that thunderstorms have such high priority there are reported above any other present or past weather codes. So it’s simply a case of writing some software to count any thunderstorms that are reported in any of the SYNOP observations. There is one problem, and it’s a very big problem nowadays, and that is automatic observations which make up as many as 90% of SYNOP observations in countries such as the UK, don’t report thunderstorms as far as I can see (although there may be exceptions – it’s a big world). That’s why when you look at the maps that I’ve produced you will see a lot of spurious zero values plotted. It’s easy to work out an automatic observation in the UK & Ireland, but not so in some other countries such as France, in time I may be to winkle out all the automatic like this, but for the moment they are included.

Anyway the top map is of days of thunder for the 1st of January to the 26th of June, and as you can Erzincan in northeast Turkey is top of the European list with 40 days of thunder, in comparison Brize Norton in Oxfordshire with 9 days is top of the available manual stations in the UK. A quick look at America and the Caribbean reveals that David in Panama is top of the list there with 58 days of thunder so far this year. Tampa has only 1 day because the observations are missing for a good deal of the time. Hopefully with a little more polish, the output from this application might be a little less ambiguous the next time you see it, for now its work in progress!

2016 certainly seems to have been a very thundery year so far, but I would have to do an awful lot more data processing to calculate a thirty year mean for a great many stations before I could say it is. At one time the Met Office published an hourly text bulletin of sferics across Europe [SFUK26], but over 10 years ago they stopped issuing it which was a big pity. The more frequent and more detailed high-resolution bulletin which replaced it [SFUK27] may still be being produced but was never made public on the internet, which is another great pity. Thank goodness for the Blitzortung organisation who had the foresight to see the importance of monitoring lightning from thunderstorms and making it freely available to all, something I thought that national weather services were supposed to do.

[Tudor Hughes]

 The total number of days of thunder here (Warlingham, NE Surrey) is 14 up to the end of June, of which no less than 9 were in June itself, a record for any month (since March 1983).  Brize Norton's figure of 9 looks at first sight far too low but in June there were a number of localised slow-moving storms in and around London.  Of my total there was 1 in each of Jan, Feb and Mar, 2 in April and 9 in June.

        As it's nearly 50 years since I was in the Met Office I'll have to ask you how the thunder is observed nowadays.  Presumably by human observers unless the automatic stations have dedicated microphones, which I don't quite see.  These observers will have other duties and may well miss the odd rumble of thunder whereas keen amateurs, especially retired ones such as myself, will always be listening for thunder except if in a noisy building. I therefore think that amateur observations would actually be more reliable than professional ones in this particular case and it may well be worth going through recent COL bulletins, admittedly a tedious process but one which I think may well give you a truer figure than that obtained from professional sources.  This would only work for the UK of course though other countries must have weather nuts with their associated organisations.  I don't suppose much of this stuff would be digitised so extracting it would be laborious.

Tudor Hughes, Warlingham, NE Surrey, 557 ft, 169 m.

[John Hall]

The same argument might apply to the number of days with snow falling, where an amateur observer might be more likely to spot the odd flake on a mainly dry (or mainly rainy) day.