Thanks Kev!  

I do like your stats but your new avatar is really scary!  

Yes, I prefer the one which he has at netweather although that is only personal preference for me.

 

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the problem with that (though not really wanting to start an argument) is that you can have a day of continuous drizzle from dawn to dusk, or one of stunning warm sunshine and a brief thundery shower lasting a minute, and they both count the same ....

I think that is probably the case, regardless of how we define an official rain day and of course, it is important to draw the line somewhere with that one.

When I first started using that term on this forum, I originally used to define a rain day as one where there is any recorded rainfall at all until I discovered that certain days were going down as rain days under this definition even though no more than 0.2 mm of rain might have been recorded during that day, with that being solely caused by condensation and/or early morning dew.

That clearly isn't a very fair way of defining a rain day and it is for that reason that I instead decided to define a rain day as one where at least 1.0 mm of rain has been recorded on any given day.  That appears (unless I'm wrong on that one) to be the official Met Office way of going about that as this is the only definition for that which I have found, from which the Met Office use any sort of LTA against which that can then compared against.

However, that particular issue which you have just described is probably one reason why everyone may well have their own way of defining what a rain day (which should maybe be referred to an unofficial rain day, rather than an official rain day for that very reason) actually is, and that is why I said that the way in which Kev Brads defines a rain day in his Manchester Index formula, might not necessarily be the same way in which I would define a rain day on this forum.

EDIT:

This scenario for defining what a rain day is becomes even more bizarre during the winter when any given day might well be recorded as a "rain" day even though that is actually a day with massive blizzards with everything falling as snow. The reason for that of course, being down to the fact that because snow is itself a form of precipitation which itself, also carries an equivalent rainfall amount as a result.

I can also see where that comes from as well because in actual fact, there is probably not a lot of people out there who don't know that most of the rain which we get here in the UK actually starts off a some higher level as snow. That isn't just the case in the winter either because that is also true, even at this time of the year especially with frontal or orographic rainfall (that is less likely to be the case during the summer though with the really torrential rain which is associated with those massive thunderstorms which we might get at the end of a heatwave).

The only reason why for most of the time (other than during the winter months) nobody will usually actually get any snow on those occasions is just simply down to the fact that even our highest Scottish mountains aren't high enough to protrude above the snow line (that is even more the case during the summer months as a result of the temperatures being that bit higher which then causes the snow line to be at an even higher level as a result).

 

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Another repellent day. The misery has infact stepped up a gear. Just appalling with endless grey skies and a ridiculously strong and cold wind. Not remotely summer-like. Typical 12C windy October rubbish.

Just ridiculous as the run of awful Saturdays goes on and on although now it is not just restricted to Saturday. It's every day that is dire. It's truly draining having to endure this dismal grey crap day in day out.

The worst start to a summer month in my lifetime 

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Glad there will be some cloud cover this afternoon. Have to blow my horn at Writhlington Village Hall Fete.

 

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Rather interestingly, I was looking back on the archives and found an old post on the netweather forum from back in 2009 where KevBrads (who has the user name of weather-history over on the netweather forum) posted the formula which is used to calculate the Manchester Summer Index.

I'm sure that there has been at least one similar post here in the TWO forum as well, although I'm not sure how easy that would be to find because I'm sure that Brian cleared out a lot of the really old posts from here at around the time when he moved everything over onto a new server.

Anyway, the formula according to that post states that the Manchester summer index = 10 x [(mean maximum temperature during summer) + (total hours of sunshine) / 67 - (rain days)].

I'm not sure if that is the formula which he still uses for that today, but it was the one which he used back then in 2009 on that old netweather post.

A lot of the replies in that old netweather forum post questioned what he meant by rain days, but I always go by number of days where there has been at least 1.0 mm of rain since that is the only such measure against which there is an actual long-term 1981-2010 average as defined by the Met Office, although that might not necessarily be the same definition which Kev uses here.

Furthermore, I would also imagine that the data for this would need to come from a whole range of weather stations across Manchester which is after all, one of the largest cities in the UK (that would equally be true even for a much smaller city such as here in Edinburgh).

Kev could just use his own data for that and refer to the result as the Manchester Summer Index. However, Bolty (as just one other example) could equally use his own data for that and the result of this could equally be referred to as the Manchester Summer Index which would be equally valid since he is also within that same city of Manchester.

Yet, the results of that from Kev would technically be different from the results for that from Bolty because although this comes from two sets of data for the same city, this data would be different for each of those two locations and as we all know, data (such as rainfall amounts) can vary quite a lot even within the same local area. That is why I'm assuming that the data is taken from a number of locations spread right across Manchester, rather than just a single location.

Nevertheless, there is no reason why a similar thing can also be done for other towns and cities across the UK and it would be interesting to see what the results of that actually were.

 

I have used the Met Office UKCP09 / CEDA 5km grid square data to do Summer Indexes for all of those grid squares covering all of the UK from 1961-2016 and I showed these a year or so ago on here. Sadly the UKCP09/CEDA files still only go up to 2016

I still have this posting and some new ones showing regional trends since 1961

As you rightly say, the Met Office use 1mm of rain as a "rain day" and and this is what is published in the grid squares. I spoke to Kevin on email the other day and he uses 0.2mm as the threshold so all my Index figures are al little bit higher as there are normally slightly more wet days on the 0.2mm basis and these have the effect of reducing the index value

The Summer Index to 5 July for London Heathrow stands at 251 on this basis and when adjusting the formula for only 35/92 way through the summer. Historically indexes for the SE are very much higher than for Manchester (!!)

(data from Weatheronline and Accuweather)

 

 

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I found the thread from last year where we discussed Kev’s summer index.

https://www.theweatheroutlook.com/twocommunity/default.aspx?g=posts&t=18969&p=15

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All week it’s been nice. However just as Pride arrives the clouds come in.

Irritating

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IMO if you truly wanted to capture the ‘feel’ of how wet a summer was, a consideration of proportion of ‘active hours’ (when most people are needing or wanting to venture out of their homes) with rain would be needed.

Sadly, as far as I’m aware anyway, most official weather stations only report 6-hourly or 3-hourly rain amounts, and often not consistently one or the other.

So possibly the best that could be done generally would be to score 1 rain day if both the 6-hourly intervals to noon and 6 pm saw 0.5 mm+, and 0.5 rain days if only one did.


. . . . . . .

After yesterday’s minor shortfall here, today’s made up for it thanks to the cloud belt being further north than had been modelled as of late yesterday. It’ stayed largely sunny all the way to 14:15 before clouds started to build more.

Temps are in the 25s again and with very light winds, it feels even warmer - quite hot in fact.

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IMO if you truly wanted to capture the ‘feel’ of how wet a summer was, a consideration of proportion of ‘active hours’ (when most people are needing or wanting to venture out of their homes) with rain would be needed.

Sadly, as far as I’m aware anyway, most official weather stations only report 6-hourly or 3-hourly rain amounts, and often not consistently one or the other.

So possibly the best that could be done generally would be to score 1 rain day if both the 6-hourly intervals to noon and 6 pm saw 0.5 mm+, and 0.5 rain days if only one did.

Hmmm!  Capturing the ‘feel’ sounds nice.  But that’s always difficult with statistics because they’re just none emotive numbers to be taken at face value. Great to use for comparison but unyielding and often misleading.  

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Sadly, as far as I’m aware anyway, most official weather stations only report 6-hourly or 3-hourly rain amounts, and often not consistently one or the other.

I find this surprising. Most of the official stations over here, of which most are now automated, report by the hour on Met Eireann, with minute by minute data being made available to the public every month. 

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IMO if you truly wanted to capture the ‘feel’ of how wet a summer was, a consideration of proportion of ‘active hours’ (when most people are needing or wanting to venture out of their homes) with rain would be needed.

Sadly, as far as I’m aware anyway, most official weather stations only report 6-hourly or 3-hourly rain amounts, and often not consistently one or the other.

So possibly the best that could be done generally would be to score 1 rain day if both the 6-hourly intervals to noon and 6 pm saw 0.5 mm+, and 0.5 rain days if only one did.


. . . . . . .

After yesterday’s minor shortfall here, today’s made up for it thanks to the cloud belt being further north than had been modelled as of late yesterday. It’ stayed largely sunny all the way to 14:15 before clouds started to build more.

Temps are in the 25s again and with very light winds, it feels even warmer - quite hot in fact.

I'm a fan of the way Kevin has put that formula together as it is fairly simple and the data is not too difficult to collect

I take the point about a burst of 1mm of rain on an otherwise sunny day compared to a dank drizzly day with 1mm spread over several hours but the following will mostly mitigate this effect in the overall index

Most summers have a "statistical" mix of both types of rain day so roundabouts and swings

The dank and drizzly day will also reduce the sun hours by more and this is also in the formula

The dank and drizzly day will often have a lower maximum temp (in summer) also in the formula

So I would endorse the relatively simple method being used

 

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I'm a fan of the way Kevin has put that formula together as it is fairly simple and the data is not too difficult to collect

I take the point about a burst of 1mm of rain on an otherwise sunny day compared to a dank drizzly day with 1mm spread over several hours but the following will mostly mitigate this effect in the overall index

Most summers have a "statistical" mix of both types of rain day so roundabouts and swings

The dank and drizzly day will also reduce the sun hours by more and this is also in the formula

The dank and drizzly day will often have a lower maximum temp (in summer) also in the formula

So I would endorse the relatively simple method being used

Good points and I agree.  

It’s not easy to add anything emotive to a statistic and that’s fine as long as we accept that it is what it is.  It’s great as a statistic for comparison over time and I think we’d just over complicate things by trying to make it a more accurate representation and as SC pointed out, the data isn’t always available. 

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We're having 2/3 days of less good weather. But that's normal for summer. As long as we don't regress back to the unrelenting crapfest of June, it won't be too bad - although I'd like a 3-4 week spell of warm & sunny as we go into August.

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I was thinking purely in terms of the rain, as funnily enough I've had a lot of months in recent years with most of a near-average rain total falling in the space of a few days max. Curiously, this was not always the case; there used to be a more even mix here.

I agree that Kevin's summer index as it stands does a mighty fine job .

 

So back onto the thread topic - after a couple of breezier, fresher days, it's calmer and more humid here today. In fact I was impressed at how warm it felt when stepping out for lunch. Temps are now rising slowly through the 23s thanks to sunny spells.

Hints of the sea breeze are starting to appear now; a rustling of the leaves outside the window. I can also see the blue skies to the south that tend to accompany it.

Striking that Bournemouth Airport's still almost as warm as here, despite a 10 mph southerly breeze. That usually drops the temp by 1-3*C at this time of year.

http://ghrsst-pp.metoffice.com/pages/latest_analysis/sst_monitor/ostia/anom_plot.html?i=34&j=2

The nearshore waters of the Channel are responding well to the intermittently sunny and mostly warm weather, despite some quite cool nights for the time of year. SST anomalies are somewhere near +3.5*C in the Solent waters. Strangely, that's only a little short of what they were this time last year after that blazing June .

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I think it's incredible that there is such a massive heatwave going on in Alaska just now (a place which has part of it up in the Arctic) whilst here in Edinburgh just now, it's pouring with rain with the temperatures struggling at just around 16°C.

To me, this is very much the summer equivalent of what we see often during the winter when we are bathed in really mild SW winds from the Canary Islands which keep it both frost-free and snow-free here, whilst places such as Greece and Turkey get hit by massive blizzards and really cold temperatures.

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July hasn't been too bad so far. Yes it's been a bit cloudy at times, but at least the days have been mostly dry and useable and it hasn't felt unpleasantly cool either. It's certainly an improvement over early June, put it that way.

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July hasn't been too bad so far. Yes it's been a bit cloudy at times, but at least the days have been mostly dry and useable and it hasn't felt unpleasantly cool either. It's certainly an improvement over early June, put it that way.

 

It's felt like a typical July to me - mostly fine, but with the odd day of rubbish thrown in

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Manchester Summer Indices 

1954 143
1907 147
1956 155
1912 156
1924 158
2012 164
2008 168
1987 169
1946 170
1909 171
1931 173
1978 173
1980 173
1920 174
1923 174
2007 174
1927 175
1948 176
1938 177
1922 178
2011 179
1985 180
2019 181 (up to 9th July)
1958 184
1972 185
1916 188
1986 189
1965 189
2016 189
1910 190
1936 190
1988 191
2010 191
1966 192
1998 192
2017 192
1953 193
1963 194
1993 194
2009 194 

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It's felt like a typical July to me - mostly fine, but with the odd day of rubbish thrown in

Yes you're right these, nothing extreme or even significantly warmer than average but mostly very 'useable'.

 

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Manchester Summer Indices 

1954 143
1907 147
1956 155
1912 156
1924 158
2012 164
2008 168
1987 169
1946 170
1909 171
1931 173
1978 173
1980 173
1920 174
1923 174
2007 174
1927 175
1948 176
1938 177
1922 178
2011 179
1985 180
2019 181 (up to 9th July)
1958 184
1972 185
1916 188
1986 189
1965 189
2016 189
1910 190
1936 190
1988 191
2010 191
1966 192
1998 192
2017 192
1953 193
1963 194
1993 194
2009 194 

Well certainly moving in the right direction. At what point would it be classed as an 'average' summer?

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