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July 2014 – warm and wet on paper

July 2014 was yet another milder than normal month; the mean temperature of 20.2C was 1.7C above average, making it the 9th warmest July since 1797 – and 0.5C cooler than last July.

The month was marked with spectacular thunderstorms and torrential downpours, contributing to what was a much wetter than average month – some 73mm fell which is 168% of the monthly average. While on paper the month looks very wet it should be noted that 52% of the July total fell in two episodes: a stalling warm front on the 10th and a cloudburst on 25th. I was away for the thunderstorm though a friend remarked that the roads close to Redbridge Roundabout were like torrents, the rain was so intense for a short period. I’ve put together a series of radar images that show the evolution of the storm, together with graphs, that can be accessed here.

The hottest day was July 18th with 32.7C recorded. There were 12 occasions where the mercury reached or exceeded 80F – pretty respectable though last July saw that figure reached on 20 days!

The sunniest day was on the 3rd when 15 hours of sunshine were recorded. Throughout the month there were 11 days with 10 hours or more of sunshine. There were also 5 days with thunder recorded – the average for July is 3.

Looking further afield there were many thunderstorms around the UK though many places missed out on the big downpours. Perhaps the most impressive was the development of the MCS that moved up from France during the evening of July 18th. There were numerous superb pictures but my favourite is probably this shot taken by Richard Dixon in Whitstable, Kent. It shows, perfectly, the contrast betweeen the bright orange sunset and the impending doom of the approaching MCS from the continent.

shot taken by Richard Dixon in Whitstable, Kent. It shows, perfectly, the contrast betweeen the bright orange sunset and the impending doom of the approaching MCS from the continent
This shot was taken by Richard Dixon in Whitstable, Kent. It shows, perfectly, the contrast betweeen the bright orange sunset and the impending doom of the approaching MCS from the continent

A thunderstorm on Sunday, July 20th, saw three inches of rain fall on Canvey Island in a very short space of time. A good round up of events, including pictures, can be seen here. The thunderstorm on 25th was felt across London and the Home Counties – there’s an excellent picture of the approaching shelf cloud here. Brighton was rudely awoken by a storm on  28th by a slow-moving thunderstorm.

It is a typical feature of summer that rainfall can vary a great deal across a small area. The nearest official station to Wanstead, St James’s Park 8.4 miles to our south-west, recorded recorded just 25.9mm – 35% of what fell here.

The nights were mostly warm – the 14.8C average is higher than last July.

Overall July was a superb summer month – sunshine, heat, thunderstorms in abundance.

Sunset on 31st looking across Wanstead Flats. July was a classic summer month for weather
Sunset on 31st looking across Wanstead Flats. July was a classic summer month for weather

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Tragic London storm marked slide into WW1

Over the years significant weather events have, at least in my subconscience, at times signalled that something ‘big’ is about to happen – just one example being the Great Storm in October 1987 that was followed days later by the Black Monday stock market crash.

So an event that happened 100 years ago this month, to some, probably also brought a feeling of impending doom as the political situation in Europe became ever more fraught.

Account of the thunderstorm reported in The Times
Account of the thunderstorm reported in The Times

A series of severe thunderstorms that broke out just after midday over south-west London on June 14, 1914, left people dead and a trail of destruction across areas south of the Thames. Fierce lightning, torrential rain, severe flooding and hail ‘the size of walnuts’ accompanied the storms. Seven people were killed by lightning on Wandsworth Common and four others were injured. As with many thunderstorms the heaviest rain, 94mm in 3 hours at Richmond Park, was focused over a small area. South Kensington, just over 5 miles away, recorded just 6mm! I don’t have the figures for Wanstead but judging by the map published in the 1914 edition of British Rainfall it probable recorded even less than South Kensington.

Some reports by observers.

Dulwich: Violent hailstorms. Many hailstones were like acid tablets about one inch long, half an inch broad and over a quarter of an inch thick. A minute or two after these had fallen, a mist rose to a height of about 4ft above the ground.

Lewisham: A storm began at 12.24pm and came right overhead from the east with terrific flashes of lightning and loud thunder. At 12.31pm, rain fell with extraordinary fury; within 9 minutes 0.5 inches had fallen. The second storm came up just after 1pm, the lightning being even more severe. At 1.30pm, St Mark’s Church, and the Holy Cross were  struck. A tree in Hither Green cemetery over 30ft high was splintered and two houses were struck at Catford. Another thunderstorm came up at 2.25pm with torrents of rain and hail as large as haricot beans fell for 5 minutes.

Rainfall in the London area - June 14, 1914 - shown in the publication British Rainfall
Rainfall in the London area – June 14, 1914 – shown in the publication British Rainfall

Richmond Park: Very severe storm passed over the house; an oak fence was struck by lightning in two places. Rainfall measurements were as follows: 1.80 inches in 45 minutes, 2.70 inches in 90 minutes, 3.2 inches in 2 hours, 3.60 inches in 2.5 hours, 3.70 inches in 2.75 hours.

Wimbledon Downs: There was a curious scene close to Kingston station, where the water was about 4ft feet deep at five o’clock and motor cars and omnibuses had to make a wide detour. The storm was especially severe in Wimbledon district, where, owing to the bursting of an overtaxed sewer, the District Railway line was submerged. At Tooting Junction station was a foot deep on the platform.

Judging by the 1881-1910 average 1914 was a warm year: the mean temperature of 10.7C  was a full degree warmer than average. It was also 15 per cent wetter than average and the sun hours were nearly 108% of average. Of course by today’s standards (the 1981-2010 average) 1914 looks relatively cool as the average annual temperature has risen 1C in the past hundred years.

The weather on this day must have been synonimous with the deteriorating political situation in Europe: two weeks later Franz Ferdinand, Archduke of Austria, and his wife Sophie were assassinated in Sarajevo by a young Serbian nationalist Gavrilo Princip , the casus belli of the First World War.

What is fascinating is that a similar thunderstorm that left seven dead in Valentines Park, Ilford, 75 years ago this August, also happened about two weeks before Prime Minister Neville Chamberlain announced on September 3, 1939, that Britain was at war with Germany.

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