Tag Archives: thunderstorms

Bank holiday sunshine. And thunderstorms

The coming bank holiday weekend is looking very warm, possibly hot on Monday. And with the heat comes the inevitable thunderstorms.

Looking at the CAPE forecast on @wxcharts the risk on Saturday looks like staying to the west of London. The best chance for east London looks like after noon on Sunday and Monday. There is no guarantee of thunderstorms here – some places could get hammered while just down the road it could stay dry – the potential is there.

Meteorologists will be keeping a close eye on Herstmonceux and Trappes ascents in the coming days.

An explanation of CAPE can be found here.

cape

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Mamma Mia! Summer storms hit Skiathos

Thunderstorms and prolonged heavy rain aren’t what you usually associate with the Aegean in August. So to experience three days in a row of inclement weather must be rare in this beautiful part of Europe.

Water from the hills above turned local roads into rivers
Water from the hills above turned local roads into rivers

Arriving at the end of a heatwave the owner of my hotel in Skiathos remarked that humidity had been particularly high though temperatures had cooled from the previous week’s level of 36C – not bad in itself but when you consider the low fell to just 27.1C those sorts of values make it impossible to sleep without air conditioning.

Sunshine on the first couple of days came to an abrupt end on the Friday night with the arrival of the first disturbance – the sound of thunder and torrential rain audible above the low buzz of the air conditioning. The storm gradually cleared in the morning to leave sunny spells by the afternoon.

This process repeated itself over the next couple of days although by the third night only heavy rain developed. Since returning to the UK I’ve had a look at statistics from a weather station located on the north of the island near Kastro. Rain totals on August 21st, 22nd and 23rd were 36.2mm, 39.2mm and 34mm respectively – bringing the total for the month to 113mm, nearly three times what fell last August. Looking at national Greek totals on Ogimet the disturbance was very localised.

Torrents of water from the storms caused deep scars in the landscape. I spotted this at the edge of an olive grove during a walk through a forest to Mandraki
Torrents of water from the storms caused deep scars in the landscape. I spotted this at the edge of an olive grove during a walk through a forest to Mandraki

The torrents of rain carved deep gorges in the paths that criss-cross the island. And during a walk from Koukounaries to Madraki part of the impacted sand/soil road down to the beach had been washed away.

Locals didn’t seem that phased by it and judging by the number of tavernas with wind down sides to their awnings it is perhaps a common feature of the climate?

Mean temperature for August was 0.3C up on last year: 27C, though the number of days of >32C was nearly half last year.

The island, part of the Sporades, is famous for being the location where the hit musical Mamma Mia was filmed – though most filming was done on neighbouring Skopelos. It’s a very green area – much more so than southern islands I’ve visited such as Ios and Crete which are arid by comparison.

During a visit to Skopelos, which has a landscape that looks almost Alpine from a distance with its pine forested hills, I was puzzled by the lack of wind turbines, especially considering how reliable wind seems to be in the surrounding waters.

One of the many stunning beaches on Skiathos. This bay is close to Mandraki
One of the many stunning beaches on Skiathos. This bay is close to Mandraki

Greece does have an extensive wind power programme though much of it is based in the mountains in the north. EU politics over energy tariffs also probably play a part.

Thunderstorms also played a part on our flight home. As we crossed the mountains of Macedonia and the Balkans to the north I could see vast cumulonimbus begin to form. The pilot made an excellent job of keeping turbulence to a minimum by steering us around these forces of nature – a couple of which reached above our cruising altitude of 39,000ft.

* Storms also affected Skiathos and Skopelos in September. A weather station on Skopelos reported 209.6 mm on 22nd September, with an additional 56.2mm on the day before and 49.2mm the day after. The month there has abundantly given 317mm, but this is *not* the wettest area of Greece for September so far. The very warm seas at this time of the year have given numerous places a lot of precipitation, backed up, of course, by great support aloft .

The storm caused much damaged and devastation to infrastructure in the towns in Skopelos.

A news report here

The island of Skopelos is even more stunning than Skiathos
The island of Skopelos is even more stunning than Skiathos
Much convection could be seen developing during the flight home as we crossed Macedonia and the Balkan mountains to the north
Much convective development could be seen during the flight home as we crossed Macedonia and the Balkan mountains to the north
The pilot made a good job of steering round the storms. It made a change to see these beasts from above - though some still developed higher than our 39,000ft cruising altitude
The pilot made a good job of steering round the storms. It made a change to see these marvels of nature from above – though some still developed higher than our 39,000ft cruising altitude
In a shop close to Koukounaries beach I noticed this selection of snowy pictures that were taken on the island a few years ago. Being north of Athens it is not surprising that they occasionally see snow here
In a shop close to Koukounaries beach I noticed this selection of snowy pictures that were taken on the island a few years ago. Being north of Athens it is not surprising that they occasionally see snow here

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

To view full stats follow this link:http://1drv.ms/1kiTuzv

 

Flashback to a period of flash floods

storm2The Met Office, earlier this week, warned us that extreme summer rainfall may become more frequent in the UK because of climate change. The research, produced in collaboration with Newcastle University, says that while summers are expected to become drier overall  intense rainfall producing serious flash flooding could become several times more frequent.

I hadn’t thought much about the story until, as part of my attempt to find out what this summer is going to turn out like, I discovered some fascinating details of several events during the summers of 1811 and 1828. Many have remarkably similar characteristics to the Boscastle flood in 2004 – the kind of episode the Met Office tells us could become far more common by 2100.

The entries for 1811 in Luke Howard’s book The Climate of London once again shows that extreme weather is nothing new and serious flash flooding was actually more common all those years ago.

May 20 1811 A severe thunder storm came on at Ingatestone, Essex, accompanied with a deluge of rain. In ten minutes the water ran about three feet deep in the streets. The same night at Potter street on the road to Newmarket hailstones nearly as large as pigeons eggs fell accompanied with the most terrific thunder and lightning.

May 27, 1811 Hereford: We were visited by a dreadful storm of thunder and lightning accompanied by torrents of rain very destructive eastward of this city. It commenced about three o’clock in the afternoon and continued with little intermission till past eight. This storm and the consequent inundation of several thousand acres of land destroyed a number of lives and much property.

June 8, 1811 A severe storm of rain hail and lightning took place in Birmingham and the neighbourhood. The hail or rather pieces of ice which fell are described as of prodigious size and considerable damage has been done to the windows.  Worcester this day another most tremendous storm of thunder lightning and rain took place about 11am equal to that of the 27th except the hail.

A storm was also experienced June 28 at Bury and its neighbourhood. The lower part of the houses were filled with water which lay in the street 5 feet deep. The hail stones 5 8ths of an inch in diameter broke near five thousand panes of glass. About twenty six head of cattle were killed last week by the lightning at Bisby and Walsham in Norfolk.

July 2, 1811 In the neighbourhood of Wonersh near Guildford after one of the most sudden strokes of thunder a deluge of rain took place so instantaneously as to carry away or destroy every thing which impeded its progress. The damage is estimated at not less than 1,500.

July 21, 1811 A heavy fall of rain did much damage at Stamford. In the meadows about Barrowden, Wakerly, Harringworth, Thorpe, Caldecot and Bringhurst immense quantities of hay were carried away. Several thousand loads it is supposed have been destroyed in addition to which the injury sustained by the land has been very great. The water rose thirteen feet in less than four hours in Wood Newton parish.

View from Greenwich Observatory toward the Royal Naval College
View from Greenwich Observatory toward the Royal Naval College

In 1828, a spring that was also similar in terms of temperature and rainfall to this year, more entries in Climate describe flash flooding events.

July 8, 1828 Extensive rains on Tuesday afternoon the 8th instant about four o’clock a storm of wind rain and hail accompanied with thunder and lightning broke over the town and neighbourhood of Taunton with a degree of violence never before remembered by the oldest inhabitant. The thunder in heavy peals was heard simultaneously from the east and west and the wind at one period of the storm blew a perfect hurricane. At Kingston the banks were thrown down for several miles and three rams the property of Mr Welch valued at thirty pounds were killed by the lightning. The corn is sadly levelled by the storm. The hailstones were of uncommon thickness and in their descent destroyed much glass in the windows of private dwellings and outhouses. Various statements of mischief have reached us from our correspondents for many miles round all representing the storm to have been of unqualified violence.  Taunton Courier

The inundations occasioned by the constant heavy rains in Flintshire and Denbighshire have proved most injurious and in some instances destructive to the iron works in those counties. The Coed Talon works belonging to the Welsh Iron Company have sustained very considerable injury, the bridges, dams and culverts belonging to those works were all carried away by the tremendous torrents and bursting of the springs. On Thursday night week the waters in the immediate vicinity of the works rose to the extraordinary height of 22ft above their ordinary level and in a few hours extinguished the furnaces such was the impetuosity of the flood and the influence of opposing elements of fire and water that the most serious apprehensions were entertained that the furnaces would have been blown into the air.

Wanstead Flats by Scott Whitehead
The Met Office says summer deluges and intense rainfall will become more common

Happily the buildings sustained the shock and no lives have been lost. It is stated by the oldest inhabitants in the neighbourhood that such awful effects from impetuous torrents were never before witnessed by them. Throughout a great part of Oxfordshire and Worcestershire the wheat and barley have suffered considerably by the late heavy rains Friday afternoon, a solitary dark cloud passed over the north end of Winchester towards the valley of Itchen Abbas the sun shining from the opposite part of the horizon. The spot whereon the cloud appeared to rest seemed to be enveloped in total darkness whence shot a stream of electric fluid accompanied by a short but tremendous crash of thunder and hailstones of considerable magnitude. So violent was its force that it killed two fine horses belonging to Mr Twitchen of Itchen Abbas and struck the carter to the ground where he lay in a state of insensibility for some time, his frock was singed by the lightning. About the same time a cottage occupied by the shepherd of Mr Twitchen s brother at Mitcheldever experienced its violence by being greatly shattered and the shepherd’s wife struck instantly dead. During the same day three horses belonging to Mr Budd of Hatch Warren Farm, near Basingstoke, were struck dead by the electric fluid and a man who had charge of them was so dreadfully injured as to render recovery hopeless. Bath Chronicle

The list goes on… I’ve had a look at all summer rainfall since 1797 to see if 1811 and 1828 were particularly wet years but the records I have, taken by Luke Howard at Stratford, are nothing out of the ordinary.

The summer of 1811 in London saw a mean temperature of 16.1C (1.5C cooler than the current 1981-2010 average) while rainfall was 211mm (just under 150% of the current average). The summer of 1828, however, was warm for the period – at 17.5C. Rainfall was high at 317mm (218% of today’s summer average). Of course totals in the areas affected in the articles would have been much higher.

So when the Met Office says climate change is going to bring more flash flooding in summer I wonder if it is the climate cycling back to a period where we’ve seen it all before.

This graph of summer statisitics shows a regular series of peaks and troughs for rainfall. The mean temperature is generally 1C warmer than it was 100 years ago
This graph of summer statisitics shows a regular series of peaks and troughs for rainfall. The mean temperature is generally 1C warmer than it was 100 years ago

*For  those interested below is a continuation of summer flooding events that plagued the country in 1811, 1828 and possibly many other events of records we have probably sadly lost.

 

Sussex The accounts from the western part of this county both on the coast and in the weald concur in stating that the effects of the thunder storm of the 3rd instant were most severely felt. So severe a storm has not been experienced since 1821. The storm on the evening of Thursday night was most violent in the neighbourhood of Chichester and lasted from eight in the evening till nearly four in the morning, the electric fluid entered a cottage at Birdham and shivered a bedstead rolling its occupier with the bed on the floor lut who escaped without injury. Brighton Herald

The almost constant rain which has been experienced in Penzance and its neighbourhood has been very detrimental to the hay harvest West Briton PL

July 10, 1828 We regret to state that the floods in this neighbourhood still continue and the waters indicate by their colour how great the mischief is amongst the hay. The Welland and the Nene are of the hue of strong tea proceeding from the essence of the hay which is entirely washed out of whatever was not stacked before the 10th instant. –  Stamford Mercury

Cambridge The late heavy rains in this part of the county have laid and much injured the corn crops and likewise considerably impeded the hay harvest Bury Herald

July 17, 1828 Sheffield In our last publication we alluded to the long continuance of hot weather which had been experienced in this neighbourhood. On Tuesday, however, a change took place and on Wednesday the rain fell more heavily and incessantly than it is remembered to have done at the same season for several summers past. Indeed not only were our two rivers remarkably high but the springs of many wells which had failed at the usual time experienced a temporary refluviation. Sheffield Iris, July 17

Malton, July 17 Every hour brings fresh accounts of the extensive losses sustained by the occupiers of land bordering on the Rye and Derwent. Hay has been floating in swarth and in cock of all sizes and the loss in various kinds of grain and potatoes is incalculable. Such a weight of rain and such a flood were never known at this season of the year. On Sunday morning last Sunderland was visited by a thunder storm. The lightning was remarkably vivid the peals of thunder were tremendous and the rain fell in torrents. The Wear was also much swollen. Great quantities of hay came down the river. From our correspondent at Durham dated Sunday afternoon: Since early on Saturday morning Durham and the neighbourhood have been visited with a succession of heavy rains insomuch that the river Wear is swollen to a dreadful height and has done and is still doing frightful damage to the adjacent fields which are overflown to the extent of many hundreds of acres many of which are meadow some just mown some in pike and some standing uncut – Tyne Mercury PL, July 17

Doncaster, July 19 I have within a few days been over a considerable tract of land in this and the adjoining county for the purpose of ascertaining the effects of the late floods on the crops. A great portion of the country through which the Derwent runs as well as the other rivers which empty themselves into the Humber has been overflowed to a very considerable depth and the consequence has been the complete destruction of the greater part of the grass which was cut and those crops which were not cut will not be worth the trouble. We regret to state that in this town and neighbourhood the weather has continued extremely unfavourable throughout the week. Scarcely a day has passed in which we have not been visited by heavy falls of rain accompanied in some instances with thunder and lightning. We have not heard of any further injury being done in the vicinity by floods but we fear that the wheat and other crops as well as fruit and vegetables will suffer greatly from the long continuance of wet weather. –  Manchester Mercury PL, July 20

Although within the last few days several thunder storms have fallen in this immediate neighbourhood we have not heard of any serious injury to life or property. On Wednesday week 9th at Great Houghton during a thunderstorm the lightning descended through the sky light which it destroyed in the roof of Mr Brook’s house and through the ceiling into an upper apartment and shook down the tester of the bed on which Mrs Brook was reposing without, however, inflicting any injury further than the alarm into which she would naturally be thrown. Its course was then along a passage in which there was a cupboard whose contents of glass and earthenware were partly demolished and the door of the cupboard dashed along the passage at the extremity of which was a young female who happily escaped unhurt. – Doncaster Gazette PL, July 21

Newark July 21, 1828 You cannot possibly have an idea of the effects of the late stormy weather and the consequent inundation of the large tract of country unless you were to see it. All the country from this place situated on the banks of the Trent down to the Humber has been completely overflown and has borne the appearance of one expansive sea.

Bedford July 22 In consequence of the dreadful and continued rains every thing in the neighbourhood of this town is in the most frightful state. The Ouse has overflowed its banks in every direction as well below as above the bridge and for miles nothing is to be seen but a weary waste of waters with islands of hay or haycocks. The early season for hay gathering in the northern counties was favourable in the extreme and a great quantity of hay out of the abundant crop was secured in capital condition. About the middle of the last week the barometer sunk rapidly and torrents of rain fell day after day till the rivers became swollen and on Sunday and Monday last vast tracts of land particularly in the southeast part of this county extending from Doncaster to Hull were inundated. Even in the neighbourhood of Wakefield the hay was seen floating in the fields and near Barnsley a great deal was either washed away or rendered useless except for litter. The corn crops have also been much beaten down by the heavy rains and potatoes in low situations have suffered from the floods. – Leeds Mercury

Whitby From the 8th to the 13th instant a succession of heavy rains has been experienced at Whitby and its neighbourhood which did considerable damage to the bridges on the Esk. On Sunday morning the platform of the elegant suspension bridge at Ruswarp belonging to James Wilson Esq MP was wrenched from its abutments and together with the cast iron pillars was thrown into the stream. The small stone bridge recently erected by Edmund Turton Esq on the new line of road was also carried away likewise a bridge at Cock mill and another in the neighbourhood of Egton. The neat bridge at East Row has been so far injured as to be passable only by foot passengers. Great quantities of timber, hay were washed away and the fields and gardens completely flooded. From all parts of the country accounts pour in of the disastrous effects produced by the late uncommonly heavy rains. From Ganstead and Withernwick in Holderness to beyond Driffield a distance of from twenty five to thirty miles the country presents an almost unbroken sheet of water. The quantity of hay corn and potatoes destroyed and likely to be so is beyond all calculation thousands of acres of the latter are literally rotting in the ground. From Doncaster down to Gainsborough and the low grounds at the junction of the Ouse and Trent the inundation is stated to have been still more destructive than in this immediate neighbourhood. – Hull Advertiser

The south western districts of Scotland appear to have been visited by the same excessive quantity of rain that has been experienced so generally over England. It would appear, too, that the crops there are in general good and that the wheat in particular promises to turn out better than in the south July 30.

 August 1828

Deal Aug 9 The wind has blown very hard the whole of this afternoon at intervals almost a hurricane. Wind WSW

Brixham (Torbay) Aug 9 At three o’clock this morning it came on to blow quite a hurricane from the SSW and continued unabated until four this afternoon since when it has been more moderate.

Falmouth Aug 9 It blew a heavy gale here last night and continued until noon this day from the SSE to WSW

Penzance Aug 9 The wind has blown a perfect hurricane from SW all this morning. Accounts of damage.

Noon. PL The storm still continues with unabated fury. Great numbers of trees have been blown up by the roots and many mows of corn in the fields are quite upset and the sheaves blowing about in all directions PL

The Thames was higher on Wednesday last than has been known at this season for twenty seven years. All the low land about Goring Pangbourn Mapledurham, Caversham, Sonning &c was under water. – Berkshire Chronicle

 

 

 

 

Heatwave? washout? Or just another changeable British summer?

chicken cloudWith all the talk of heatwaves this week it won’t be long before the media switches from piping on about the UK facing “10 years of miserable summers” to “Is our climate getting warmer?”.

But the simple fact is that the UK’s climate has always varied greatly – some years, as in the last two, the pattern for summer has brought mostly miserable weather. Other years we get a run of warm, dry summers.

A case in point was the heatwave of July 1808. Far removed from images of freezing Georgian winters and miserable summers the July of 205 years ago was among the warmest ever. The monthly mean for July 1808, according to the Central England Temperature series, was 18.4C – the 6th hottest July since the beginning of the series in 1659.

Readings taken by Luke Howard at Plaistow show the build up of heat to the 14th. The series on the right, taken in Wanstead, around 3 miles to the north-east, will be added to by the author as July unfolds
Readings taken by Luke Howard at Plaistow show the build up of heat to the 14th. The series on the right, taken in Wanstead, around 3 miles to the north-east, will be added to by the author as July unfolds
Luke Howard, the ‘father of meteorology’ who at the time lived in Plaistow, referred to the heatwave in his diary on July 13th: “Temperature at 9am 84F. The intense heat of the maximum lasted nearly three hours till about 4pm. At 6pm the temperature was 90F.” Another entry mentions a reading taken nearby. “Another at Plashet, a mile and a half eastward, indicated 96F as the maximum under the shade of a house.”
While Howard’s methods of measuring the temperature ran short of modern standards, his thermometer was hung under a laurel bush, the values still give a valid insight into the heatwave.

Tales of the heatwave, which particularly affected east and north-east England, can be seen in letters sent to local newspapers around the country. Many describe labourers dying from heat exhaustion while working in fields. Farm animals and horses suffered a similar fate. One letter from Hull, published in the Coventry Mercury, said: “At Sigglesthorne, the honey in some beehives melted, ran out upon the ground, and most of the bees drowned in it. At Sutton, a lamb and a dog belonging to the Rev Mr Croft of Rowley, expired in the heat; and several birds dropped down dead, while flying over the streets of this town.”
Of course it is impossible to know about the health of people and animals that died but that birds dropped out the sky suggests extreme heat.

screenWhile temperature records of July 1808 are not unheard of in an English summer one record that remains is the size of the hail – which fell in damaging storms when a thundery breakdown arrived on the 15th.

The main storm missed Wanstead and the surrounding area – though Howard, writing in his Plaistow observatory, knew the weather was on the turn: “Dew on the grass, a fine breeze from ENE. Much lightning in the west this night, a few drops of rain.” Howard would have been referring to all the action about 120-odd miles west where one of the most ferocious storms in recorded history was unfolding.

Much was reported in the local press on the days following the storm which affected an area from Somerset northwards. As well as local records Luke Howard also noted national events in his diary: “After several days of uncommon and oppressive heat the city of Gloucester experienced a storm of thunder and lightning which extended many miles round and exceeded in awful phenomena any one remembered for many years past.”

Trees were “shivered to atoms”, livestock killed by lightning, crops were ruined and countless windows and glasshouses smashed by huge hailstones. A lot of the detail of the storm was compiled by a man named Crocker, then governor of Frome school, Somerset. One account from Batcombe describes a hailstone that measured 13.5 inches in circumference. To give you an idea of the size of a 342mm circumference hailstone I, with the help of my daughters, made one of my own.

It is thought the size of the 1808 hailstone may, along with a storm in 1697, be the national record for hailstone size - being 20mm greater in diameter than those measured in a Horsham, Surrey, storm in 1958
It is thought the size of the 1808 hailstone may, along with a storm in 1697, be the national record for hailstone size – being 20mm greater in diameter than those measured in a Horsham, West Sussex, storm in 1958

Howard’s report continues: “The most tremendous circumstance of this storm was the destructive hail shower which accompanied its progress.”

The Tornado and Storm Research Organisation (TORRO) grades haistorms from H1-H10, where the hail increases in size from 5-10 to over 125mm in diameter. From the historic descriptions the 1808 storm was an H8/9.This exceeds the British record made during the Horsham, West Sussex, storm of September 5, 1958, which produced hailstones up to 80mm in diameter. Hailstones for the 1808 storm were about 109mm in diameter. Since 1650 there have been 119 independent H5 hailstorms in England and Wales.

Since 1900 there has been a halving in the frequency of recorded destructive hailstorms. Scientists are undecided on whether this is a result of climate change or just a variability of the British weather. But any future uptick in destructive hail should be tempered by this historic record.

It is my belief that people’s current expectations for summer were raised to unrealistic levels when we had a run of warm, dry summers a few years ago. The fact is that because of our maritime climate warm, dry summers occur in this country only occasionally. ‘Default’ summer weather is changeable, rather cloudy and, for many in the north, rather cool

So, if any media outlets do start coming out with any stories of “unprecedented heat” or “worst storm in history” bear in mind that it has probably all happened before.

Scott Whitehead
@wanstead_meteo
http://www.wansteadweather.co.uk

Whatever happened to proper summer thunderstorms?

Is anyone else yearning for a good old-fashioned summer thunderstorm? As we move in to what is traditionally the most thunderstorm-prone month – the Met Office average for this area is three days of thunder – you would be forgiven for thinking that we have plenty to look forward to.

Looking north toward Aldersbrook. The Flats can be very exposed during a thunderstorm
Looking north toward Aldersbrook. Wanstead Flats, a 186 hectare open space that is larger than Hyde Park, can be very exposed during a thunderstorm

It was George II who some time during the 1730s apparently characterised the British summer by saying that it was ‘three fine days and a thunderstorm’.

The reality these days, at least in this part of the country, is quite different. Yes, brief fine spells do still break down – but the classic stormy nights I can remember being kept awake by when I was a lad in the Eighties are now a distant memory. A look back through the records shows that our most thundery month happened in June 1982, when thunder was heard on 13 days. On the 2nd a woman was killed after being struck by lightning while walking in a park in Willesden. More storms followed over the next couple of days and there were three more deaths in the UK caused by lightning. One thunderstorm over Loughton flooded 200 houses, some up to the ground-floor ceiling and at least 12 properties were struck by lightning. One observer recorded 79mm of rain, one and a half times the monthly average, in 90 minutes.

Despite a couple of instances of good potential for thunder this past month has been, so far, completely thunder-free, with all the activity passing well to our east. On June 20-21, there were 235,809 lightning strikes in 24hrs over Germany. To put that into perspective the UK, on a typical ‘thunder day’ in summer, receives up to 10,000 ground strikes although the exceptional day of 24 July 1994 produced 85,000 ground strikes.

The meteo is sited on the Aldersbrook Estate and uploads data to the web every 10 minutes, 24 hours a day
The meteo is sited on the Aldersbrook Estate and uploads data to the web every 10 minutes, 24 hours a day

So what is the potential for thunder in July? Looking back at Wanstead and the surrounding area’s local records the average number of days that thunder was recorded works out as 3.5 – though some years thunder occurred considerably more than others. But to get thunderstorms first we need the ingredients. The classic scenario happens at the end of a short heatwave, a cold front advancing from the west undercuts hot and humid air that has been in occupation for two or three days. If there is sufficient moisture in the upper atmosphere, cumulonimbus clouds will bubble upwards to the base of the stratosphere, and thunderstorms will soon follow.

Apart from the first couple of unsettled days at the beginning of July the above scenario looks unlikely to happen at least in the first half of the month. The North Atlantic Oscillation is predicted to stay positive into July – this spells good news for us as it suggests that the Azores high will dominate our weather, bringing lots of fine and dry conditions. With the jet stream and westerlies being kept just north of Scotland, temperatures should be average to slightly above. It is possible that the high could further dominate as the month goes on. But it is also possible that pressure will start to fall after around the middle of the month. Though it is impossible to predict in detail perhaps a date of around 20th would be the most likely for thunder?

It is too soon to say if the recent trend for a paucity of thunderstorms is just a blip. It could just be another typical variation of the British weather and we will shortly see an upturn in summer thunderstorm activity.

Scott Whitehead
@wanstead_meteo
wansteadweather.co.uk