Unusually violent storm in the United Kingdom - analysis or comments please

Ian Hutton

Ok.. where to start.. I’m a farmer from the UK and yesterday I had THE single scariest experience I’ve had in long time – that of nearly being struck by lightning – lots and lots of times, with nowhere safe to go to. This storm was the most violent storm I have ever experienced in this country, and topped several storms I’ve seen in the USA as well. What I would like if possible is some more information / a detailed analysis about this bizarre storm – it is a rare event in the uk, so what caused it to randomly form and be so violent? How much danger was I really in / (i.e how lucky am I to still be here!!) how severe was this storm and how would you guys rate it (e.g 1 very severe, 10 mild) compared to the storms you guys chase and what on earth was the weird cloud formation as it the storm approached? I.e some more technical/ish information would be great. What follows is my experience, take as much or as little info as you need….

Background: we had some weak storms the previous night, not too violent with rumbling thunder, none came right over and from what I could see mostly sheet lightning. We have a low pressure system over the uk at the moment that has stalled and is spiraling, I’m in the south east where temperatures peak at about 23 degrees during the day. On the morning of the event the area I’m in is on a severe weather warning from the UK met office for severe heavy rain and flash flooding, no mention of lightning though.

I got in the field about 9 am, and noticed that the clouds were banking very tall, much taller than usual. It was quite breezy with sunshine broken by scattered clouds, and expecting sunshine and showers thought nothing of it, but I do remember noticing how unusually tall these clouds were, they were like the normal “fluffy cotton wool†clouds we often get but with tall tops, pyramid shaped, and I watched carefully, they were growing, bubbling over at the top, but not very quickly.

About 10.50 it’s getting very dark in the direction the weather is coming from. I see one or two flashes in the clouds in the distance, and one bolt go from the cloud to the earth. The clouds are moving very quickly, and I hear a loud peel of thunder over the noise of the blackcurrant harvester. The harvester is made entirely of metal, and is open topped, so I switch off the machine and get towards the side of the field, not wanting to take any risks. I have no other vehicle in the field and because the crops needs irrigating the field is filled with metal water pipes about 6ft tall and 20m apart in the rows of blackcurrant bushes.

The cloud seems lighter underneath with an exceptionally dark rim at the front. Lightning is now hitting the ground each time with the flash to the bang about 10 seconds and getting less, and it’s doing so about once every 20 seconds. I now feel very scared, and realize the only thing I have to shelter in is a half tone plastic bin used to collect the blackcurrants at the side of the field. I turn it on its side and climb in, but at the same time keep peering over the top – I’m captivated by as well as scared by what’s going on.

It’s now about 11.05. I notice that a “normal†stormcloud (for the uk anyway) typically causes the wind to rise as it approaches, and has like a skirt of cloud around the bottom as it approaches with just grey behind it, where the rain, (and inevitably lightning) is. Also just before the skirt the clouds ahead of it are always very low but look like they’re being pushed upwards, looking like cloud cobble stones. This storms was different. The skirt was very low indeed – the lowest I’d ever seen it – about the height a light aircraft would fly at, and it was frothing violently and moving downwards. Lightning was all around by now, and hit the field I was in twice and the woods at the back of the field four times, then the rain started. There was no hale, only rain, but I could not see more than 3m in front of me. Lightning continued to ark about once every 15 seconds, but I couldn’t see where because of the rain. I cowered in my bin, flashes and bangs were instantaneous, my heart was thumping. About 5 minutes later it had passed, and about 7 minutes later the sun came out.

Take from this what you will, any comments / information / explanations would be most welcome.
 
Sounds to me like you witnessed your first and rather somewhat rare UK supercell. There are a few Brits that post on here that might be able to post more on this. But thanks for the story it's certainly a good read. What part of the UK are you in? Oh and welcome to the forums!
 
Thank you Mr Hayes for the warm welcome. I am from a village called Feering just outside of Colchester which is in the south east of the UK, just north east of London.

Regarding my previous post my the only other information I can think of was that as it approached I was driving the opposite way and could not see what was going on clearly. When we stopped my colleague on the harvester described what he said were "2 large clouds both producing lightning that had merged together in the past few minutes" which is just before the 10.50 entry on my previous post.

As I mentioned being scared and captivated I forgot I had my camera phone with me, but a second violent storm came over later in the day, and a few photos I got of its approach are attached below. This one produced the same intensity of rain, and plenty of lightning strikes to the ground, but not nearly as many as the storm described in my previous post. This time I made sure I got back inside quickly!

As I drove off the field on the harvester and headed for cover I took a picture of the "bell rim" of the cloud as I describe it approaching very fast, but this rim was much higher up than on the storm described in my previous post, and not "frothing" downwards, can anyone tell me what was going on in that part of the cloud?

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Welcome to ST, Ian! Sounds like a pretty strong storm. Props to you for getting off the equipment and to shelter! Being dead sure isn't worth a few bushels of black currants.

As above, I'm sure that there are several Brits on ST who could comment on the specific situation yesterday. But my personal metric for remarkable in a single storm cell is lightning at least every three seconds or so. The more severe can produce one a second or better.

Again others would be more informed. But what you describe sounds like you were on the receiving end of a downburst from a storm cell that developed into a very unstable mid-level layer. The most frequent lightning can come before the precipitation has a chance to fall below cloud level; the downward frothing you describe would indicate the shear area as the downdraft is pushed ahead of the precipitation mass. The sudden onset and very heavy localized rain seems consistent. FWIW.
 
I found this image of the UK at 11:00 on 17/07/2009. It shows some rather intense activity in the northeast.
 

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Well Ian, welcome to the forum!
Sounds like you had an experience that gets many people interested in the weather. Many of us here had encounters not unlike your own that has transformed into discovering more. We even learn to enjoy and appreciate what weather is. After such harrowing experiences as you had - it may well have sparked your interest as well. I got interested in severe storms after a rare and brief tornado touched down - only two miles from my home in California - back in 1998. It sure got my attention! As well as my interest...

I think the previous posters have pretty well sorted out what happened with your storm.
Yes; you were in a great deal of danger from what you described here. There are an average of ~100 people killed by lightning in the US each year. It is an equal opportunity killer, and commands respect and knowledge if you must work around it.

Q: Did at any time while the lightning was crashing about you - have the sensation of all of your body hair being raising up on end?

If so; then you were in the highly-charged static field and very well could have been struck. But with so many metal objects around you, all you would have needed to do was get low on the ground. If there was a lightning discharge close enough to you, you may have well become the victim of an indirect lightning strike. Which in itself is still dangerous and will require medical attention. Obviously, that didn't happen - so much the better!

Storm chasing is a bit dangerous for this reason. Although we can see where a tornado/strong winds/hail/rain downpour can/will occur; one cannot predict where lighting will strike. Some of the stronger bolts occur well outside the range of the storm base. Not to be trifled with!
 
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Thanks again to everyone for the warm wellcome and all the replies.

The date was indeed 17/07/2009. The "A" on the picture below is the exact location where the event occurred, in the south east of England just north east of London.

In answer to Rob - no thankfully my hair did not stand up on end at any point, I was aware that if that happened (ironically from watching storm chasing programs on discovery) it meant I was very likely to get hit, or that something nearby was. If I'm in that situation again, bearing in mind I am near no buildings or cars that I can get into, what is the safest thing to do? Was the upturned plastic bin the best place to go to?

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Much usefull information can be found on the ukweatherworld forums - synoptic discussion, convective forecasts, reports and chat.

This is the convective forecast for Friday 17th (A TORRO discussion rather than watch):

Convective Forecast

Convective report for Friday:

Reports

Synoptic discussion for cyclogenesis event 16 to 18th July - the system that brought very heavy rainfall to parts over the last few days - much flooding and also many reports of funnel clouds and at least one tornado:

Synoptic analysis

BTW. My parents live in Layer-da-la-Haye - it's small world!

Regards

Stuart
 
I actually live in Colchester, and we got some very intense rainfall that Friday morning to go with the active storm the previous night. We also go a nice storm around 6:30pm which I chased around the Dedham & Little Bromley areas. There was a nice lowering over the A12 near Stratford St Mary. It's certainly been an active six weeks for storms in the area the best being a few weeks back when a storm really unleashed near Clacton and there was some nice rising scud motion with that storm to the East of Colchester. Looks like a cool quiet period for the next couple of weeks at least, maybe the odd heavy shower we'll see.

Steve Smithson.
 
From your description and trying to picture in my mind based off your photos it sounds like a shelf cloud. They can be very intimidating and have some crazy motions within them. A shelf can be on the forward flank of a supercell or along the entire leading edge of a line of storms. Glad you made it out ok. Ive never been caught in an open area during a ligtning storm like that but I can imagine it being pretty scary, you just never know where those things are going to hit.

Heres a photo of one before it rolled over my house:
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and after it passed
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Welcome Ian, it's good to have you here. It looks like you all have had quite a bit of beautiful nasty weather lately. I wish I were there instead of in TN at the moment.

I'm looking forward to September. We are going to visit some relatives in Norwich, Yarmouth, and some other towns in the Broads. I'm trying to learn a bit about the area before we go. From the photos you posted and those I've seen elsewhere, it is a beautiful area.

And be careful with the lightning. It's hard to second guess your choice of shelter because it obviously worked for you. But I would definitely recommend heading for shelter as soon as you see lightning if possible. Stay away from high places, trees, pipes, fences, and pretty much everything you described in the field. That barrel might have offered a bit of protection from ground currents from a nearby strike, but probably wouldn't do much for a direct hit. Cars do a decent job of that because of the Faraday Cage effect. But plastic barrels, I just don't know.
 
Ian/all - I wrote the following convective discussion for TORRO on the morning of the 17th:
THREATS

Isolated tornadoes; marginally severe hail/wind; heavy rain; CG lightning

SYNOPSIS

Large, complex upper low across the British Isles, with moist and unstable air within its circulation. Several convergence zones rotating around it should focus shower/thunderstorm development, and the enhanced vorticity may contribute to a risk of convergence-zone tornadoes, as well as hail/gusty winds. Heavy rain/CG lightning also likely.



Having had a look back at the radar, the area of storms which moved northwards through the morning had its roots in a dry mid-level punch of air, along with a surface boundary/pseudo cold front. The combination of synoptic lifting of the dry intrusion (=steeper lapse rates) and heating/low-level convergence produced a line of thunderstorms. These became even more widespread as they moved away north of you, and in fact lightning was widespread and frequent across quite a large area.

However, I don't think it was a supercell, as shear was not that high, and the radar suggests a line of storms. However, the doesn't detract at all from the experience you had!
 
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