Possible 30c

[Upgrade]

Taking 30C in the middle of London as an authentic reading with all its urbanisation heating and dust is as unrepresentative as taking a deep highland frost hollow in winter with a very low reading under clear skies and snowfields.

Tamara

it may be unrepresentative but it still reached 30 degrees here, heat island effect or not, which is what we are arguing about at the end of the day.....

sorry.........i'll get my coat.

[snowray]

Here are the years when 30C hasn't been reached.

1993, 1981, 1980, 1978, 1972, 1966, 1965, 1963, 1962, 1958. 1931, 1927, 1920, 1913, 1910.

As you can see it is rather unusual not to exceed 30C especially during these supposedly warming times. If you consider our rainfall totals also this summer it just goes to show what an amazingly poor summer it has really been. Note how apart from 1993 the last time 30C wasn't reached was during those cold winter years of the late 70's/early 80's .

Interesting, 1962, 1963, 1965, 1978 and 1981 stick out! (Being followed by some severe Winter weather)

[Bobby]

Interesting, 1962, 1963, 1965, 1978 and 1981 stick out! (Being followed by some severe Winter weather)

We can dream...

[Thundery wintry showers]

The fact is, it probably reached 30C somewhere in 1993, but no official site reported 30C or above. For historical purposes, we need to compare like with like- it's like Philip Eden comparing the CET for 1-6 August with the 1971-2000 average for 1-6 August and not the whole of August.

[Spirit of 1740]

The fact is, it probably reached 30C somewhere in 1993, but no official site reported 30C or above. For historical purposes, we need to compare like with like

Indeed. I was trying to make exactly this point yesterday. It's OK for people to report their own obervations and reports from non-standard sites, but they must realise what will go into the history books and what won't.

Edited August 8, 2007 by Spirit of 1740

[grab my graupel]

Here are the years when 30C hasn't been reached.

Note how apart from 1993 the last time 30C wasn't reached was during those cold winter years of the late 70's/early 80's .

Hi Dave.

Thanks for those stats, very interesting. I must say I very much like the sound of the above.

[West is Best]

To those stating above that 30C was not reached, this is not entirely addressing the point in my opinion. It was reached, which is why it is currently registered on the Met Office / BBC site. The question is not whether it was reached, but whether it was valid.

The problem here is clearly not that of the siting of the LWC, which is incidental, but that of urbanisation. The centre of London has an effect on heat. It will certainly be interesting to see the St James' Park reading. The park, which I know well, will be marginally less affected by concrete of course.

I do repeat my earlier question, which is a little more subtle but possibly important for the future: just how do we measure temperatures in an increasingly urbanised world? When connurbations grow very large do we cease measuring in them? What about Hong Kong ...? If you think this is abstract, then we should consider the population explosion in this country over the past 100 years, and project how this may continue in years to come. May we not end up with a situation of such increasing urbanisation that rural thermometres become the exception rather than the norm? I know the CET custodians do try to monitor the urbanisation affect, and make adjustments accordingly, but presumably this process is finite.

I suggest a compromise here: the acceptance that 30C was reached in London, but that this is affected by urbanisation. This is a much more solid basis on which to proceed in the future with increasing connurbation. My only caveat is that there's a danger that 'purists' who only want to maintain rural temperatures are in danger of fossilising themselves: that the little pockets of rural mercury will continue to diminish over the generations. Perhaps we should just accept that a place like London is bound to throw up anomalous readings. In this regard I don't entirely see Tamara G's point about a frost hollow. We do accept record cold temperatures in frost hollows and there are notable cool sites such as Shap which do make the record books.

I think we should proceed on the basis of putting a * by temperatures which may be affected by the urban island effect. That doesn't mean 30C wasn't reached in London: it clearly was 30C in London on that day, but the key words here are not '30C' but 'in London' ... with all that this entails when setting against past records, and in the future.

[Nick H]

The problem here is clearly not that of the siting of the LWC, which is incidental, but that of urbanisation.

No, sorry, this is wrong. As far as I'm concerned, it is the siting that is the problem. The Met Office have a station in Manchester Hulme Library in the centre of Manchester. As far as I'm aware, it is a standard site - so fine, I would accept readings from that site. Similarly, Heathrow Airport is certainly not representative of its surrounding area, but it is a standard site - so readings from there are fine, too. If 30.3C had been reached at Heathrow no one would be complaining (at least I wouldn't). So I have no problems with urbanisation or the continuous concreting of the Earth's surface that is taking place when it comes to the reliability of weather recording. It is the criteria that a station must meet that determines whether a station is official or not.

I'll admit: it sounds anal, and almost certainly is, but we have to go by official definitions. The Met Office's own criteria mean it is non-standard and hence we must disallow it. But that does not mean we should regard LWC as a useless station, far from it. It certainly is a very useful guide to the UIHE. And I'll repeat: it is my belief that 30C would have been recorded in London on Sunday had there been a standard site.

NB Why don't they just put a standard station at Trafalgar Sq, on the forecourt at Charing Cross, or at Hyde Park Corner. Why do they persist with LWC at Clerkenwell?

Edited August 8, 2007 by Nick H

[Thundery wintry showers]

I think the above isn't entirely accurate- there are many urban (or at least semi-urban) sites, the readings of which are accepted as official. For example, Heathrow Airport and Kew Gardens in London are affected by the urban heat island effect, as they generally report higher minima than nearby rural sites. However, if a reading of 30+ occurs at Heathrow or Kew, it goes straight into the record books.

Paisley, near Glasgow, has a few entries in the record books, yet the site has heavily urban surroundings, illustrated by the fact that minima are over 1C higher than at most rural sites around Glasgow.

The reason why London Weather Centre is unofficial is due to the siting of the instrument, not the urban heat island effect.

Edit- Nick H got there first!

Edited August 8, 2007 by Thundery wintry showers

[West is Best]

Nick and TWS your point is interesting, and to a large extent I therefore stand corrected (yes I admit to being somewhat wrong ... is OON around?!). At the same time you are both suggesting that 30C was basically reached, and would have been recorded as such, if the only properly central London station was sited properly? Very good point about Heathrow.

I seem to remember a major argument last year about the new-ish site that broke the records: Charwell isn't it? Isn't that near the end of a runway or something?

The only reason I don't want to retract all of the post is that bigger point about urbanisation and the effects of connurbation. I can see real issues about this in future generations. And, assuming climate change is happening, we'd sure as heck better get this sorted before the 40C mark gets reached in the UK. If it happens at the LWC I can see a major row brewing!

[Spirit of 1740]

ROFL.

It seems that some people are going to argue until they're blue in the face that the reading on Sunday was somehow valid for statistical and historical reasons. Well, to that I say this. You can believe what you like, but the fact will be that only the standard readings will be used for statistical and historical purposes. Unless 30c is hit at another station, it will become conventional wisdom over time that it wasn't reached this year. If you want to hold a different view on that, that is your own problem.

[shuggee]

I'd have thought a recorded air temperature using a simple set of rules about siting, would mean that that temperature was recorded - which is what a recorded temperature is?!

[SP1986]

To those stating above that 30C was not reached, this is not entirely addressing the point in my opinion. It was reached, which is why it is currently registered on the Met Office / BBC site. The question is not whether it was reached, but whether it was valid.

This is the most succinct point of the whole topic I think - Is it a case of whether 30C was reached or whether it was valid.

30C was reached somewhere in the UK thats near certain, however for cases of historical recording it was not valid.

I think that is pretty much where the debate has been.

[shuggee]

The question as to whether this recorded temp of 30.3ºC at an official meto observation site (as described on thier website) will be official in that it will show up in the records could be solved in two ways:

1. Has LWC's stats ever been used to show something official in years' past - i.e. is there a temp, a rainfall stat or a sunshine stat in previous years that uses LWC's readings and is there in the public record?

2. If not, then at the end of the year, or indeed at the end of this month in the monthly meto summaries, we will have to wait and see if this is referred to by the meto. That will answer all the questions

[Thundery wintry showers]

I wouldn't suggest Hastings is used as an official site as much as the top of the London weather centre.

I think it is. In the Weather Log that comes with the Weather magazines every month, only official Met Office sites are used in the table- and Hastings is one of them.

Hastings rarely features in the "highest max temperature" tables because of its coastal location, but I quite often see the Met Office and BBC saying "the sunniest place today was Hastings with 15 hours of sunshine"

[Weather-history]

To those stating above that 30C was not reached, this is not entirely addressing the point in my opinion. It was reached, which is why it is currently registered on the Met Office / BBC site. The question is not whether it was reached, but whether it was valid.

And it ain't as the e-mail reply I got from the Met Office shows.

Since it is not valid, then it wasn't reached (unless somewhere else has recorded it officially).

It's like taking a wicket (except a run out) off a no-ball. You got the wicket (you reached 30.0C) but it doesn't count because you breached cricket rules (the station is not standard).

Therefore it doesn't count.

Edited August 8, 2007 by Mr_Data

[West is Best]

1. Has LWC's stats ever been used to show something official in years' past - i.e. is there a temp, a rainfall stat or a sunshine stat in previous years that uses LWC's readings and is there in the public record?

Well it's used to measure whether there's an official white Christmas Only a snowflake falling on the London Weather Centre between 00.00 and 23.59 on 25th December counts as an official white Christmas, although I know there are also regional bets on top of that one.

So it is used for at least one official metereological statistic ...!

[Thundery wintry showers]

Re WIB's White Christmas:

This is true, but temperature readings are subjected to more stringent sitation criteria than occurrences of sleet or snow falling. The same goes for rainfall and wind speeds.

The fact is, a station could quite easily be taken as 'official' if it was in a city centre, provided that it met the Met Office criteria for Stevenson screen height, building proximity etc. By contrast, if a station was in a remote area but the thermometer was situated unscreened in a field, it wouldn't be 'official'.

The reason why they do this is so that a line is drawn somewhere. I'd have an issue with it if the line kept moving, but there's no way that would happen here- the MetO want to keep the line in a consistent position so as to make current records consistent with historical records. Why does a line need to be drawn? Put simply, because otherwise you could put a thermometer, unscreened, resting on a large expanse of concrete and say "officially it reached 46C today!"

[Spirit of 1740]

The question as to whether this recorded temp of 30.3ºC at an official meto observation site (as described on thier website) will be official in that it will show up in the records could be solved in two ways:

1. Has LWC's stats ever been used to show something official in years' past - i.e. is there a temp, a rainfall stat or a sunshine stat in previous years that uses LWC's readings and is there in the public record?

2. If not, then at the end of the year, or indeed at the end of this month in the monthly meto summaries, we will have to wait and see if this is referred to by the meto. That will answer all the questions

The answers to those two questions are no, though as far as I know there is no public record, and yes, they may well report in their monthly review. The answer to the second question one doesn't affect the first one though.

[SP1986]

I think there is always going to be arguments about the validity of standard stations, and although the met-office does have its own requirements, such is the variability of the UK landscape and its effects on weather, you will always get even standard sites setting a benchmark different to another one. However i agree with the point made by Nick H about perhaps getting an official site in trafalgar square as I think as much variability between rural and urban will paint a better, more accurate picture about the UK climate especially in UHI's.

I have to say I do find microclimates incredibly interesting, and thats where much of my pre-postgraduate research lies. As such statistical ethics are not my thing, however I would also agree with what was said yesterday by Spiritof1740 that the sites do need to be set at an exact benchmark in order not to create confusion.

I think of statistical validity as a religion, one person will have their point, and another theirs, but such is the ethics involved there will always be disagreements.

Actually, personally I take my recordings from Prestatyn, as Prestatyn and here has identical conditions, similar effect by topography etc, even though its not a met-office official site (I dont think), Its very accurate, and I will always take my personal official temperatures from Prestatyn rather than my own thermometer (I dont always trust my positioning) or even Hawarden which is the official site.

[West is Best]

It's like taking a wicket (except a run out) off a no-ball. You got the wicket (you reached 30.0C) but it doesn't count because you breached cricket rules (the station is not standard).

Having thought about this Kevin, I think a slightly better cricket analogy would be a century scored by Pietersen in a one-day international. Would it count towards the first class averages? No. Would he still have scored a century? Yes. It's possible for both to be true!

Did it reach 30C? Yes.

Was it valid for the purposes of long-term metereological records? No.

(By the way, am I right in thinking the St James' Park reading doesn't come in until the end of the month then?)

[Thundery wintry showers]

I have to admit that I'm no stranger to this kind of issue. My personal weather equipment has always been prone to over-reading for daytime maxima, as there have always been 'sun-trap' issues with regards instrument sitation. Thus, I did a detailed analysis earlier this year comparing the readings my different thermometers give, and also nearby weather stations, and used this to reconstruct my weather records with estimated 'standard' temp readings.

South Shields Weather Station, Newton Aycliffe, Ferryhill and Newcastle Weather Centre (up to Sep 2005) may or may not have been 'official' sites but they are accurate enough to be among the list of sites I compared my readings with; Durham University Observatory is definitely 'official'.

Even today I allow for inflated readings of up to 2C on sunny summer days because of my Stevenson Screen being in a bit of a sun-trap, though in the case of minima, and maxima in the winter half-year, I provide my raw readings unaltered.

[saint]

so did we hit 30c or not :lol: i am confused

[TEITS]

so did we hit 30c or not :lol: i am confused

The best way of summing it up is yes we did but it won't count which is what matters at the end of the day.

[Gavin P]

It did hit 30c, but NOT at an official Met Office station, which means that the record books will say NON, unless theres a footnote.