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vortex_liam

2010: Lacking In Thunder

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Hello,

I've been curios whats been causing our set ups to be rubbish for storms. Is it the winters we've been having. I know there was another thread about this in august time. But this one has a difrent question.

I have a feeling it is the winters we've been having that is stoping our storms. As most of them never went over the channel.

In 2005 and 06 we had verry poor winters with verry little snow yet we had a great summer storm wise. Can you help by naming a year which has had a good winter and storm session? I know that in america in tornado ally they get a fair bit of snow during the winter and yet they still get great storm sessions. I had only 1 short isolated thunderstom this session but had a great winter at the start and now. What is it takeing our storms?

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I'd really like to find out too! I miss our storms :( I keep meaning to research it.Will start looking soon.

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I'd really like to find out too! I miss our storms :( I keep meaning to research it.Will start looking soon.

I'm starting to wonder whether it's connected to the North Atlantic Oscillation (NAO)...through much of the 90s and early 00s, I suspect the NAO was characterised as positive. A positive NAO means that pressure systems in the atlantic tend to be stronger (i.e a greater pressure gradient between the High and Low pressure), which in turn causes milder, wetter air to be pushed NE across the Atlantic from the US. The milder and wetter air masses collide with NW Europe, keeping much of the UK and N France wet and mild and in turn keeping snow events at a premium, particularly for southern areas.

During years of Negative NAO however, pressure systems are weaker, leading to the milder and wetter air being pushed more W to E across the Atlantic towards the S Med/N Africa, in turn allowing the colder, drier air to drift further South across NW Europe...this has been true for the last few years and certainly this year so far.

If we translate this theory into thunderstorm conditions...

During years of +NAO, we have effectively stronger weather systems. If we think of stronger low pressure systems coming nearer our shores, this means stronger, deeper airflow from the deep med/N Africa (i.e the perfect plume), briefer heatwaves BUT more erratic breakdowns, in the form of rashes of heavy showers and thunderstorms. As pressure systems are relatively stronger between High and Low pressure, it's fair to say weather patterns are more dynamic...more dynamic exchanges of high and low temperatures is ripe for storms in the UK.

If we consider the opposite situation...gradients between High and Low are weaker, meaning Lows tend to be less deep allowing Highs to dominate and become blocking...this has been true over the past few years, with dominating highs bringing sustained dry and wet, hot and cold periods to the UK (remember the Mid atlantic ridge Jul-Aug this year, ruined the second half of our summer in the SE lol) with Lows being slower moving and weaker, thus causing a less erratic change of weather conditions (heatwaves tail off more gradually than sudden drops).

While the science I've stated may not be totally accurate, I think by and large its a fair assessment.

As a final point, if we translate the above into a perfect plume set up, but in a year of +NAO...deep area of Low Pressure to the West, strong High to East...deep, strong feed of hot, humid air from the south, over the Spanish plateau, nice unstable atmosphere, storms erupt over France, the strong winds between the two areas of pressure forcing to the storms northwards to our shores...lovely!

In a year of -NAO, weaker feed of air coming in from the South as the two areas of pressure to the E and W are relatively shallower. Storms build, but due to the lack of strong winds feeding them North from France, the coriolis effect and the prevailing SW winds drift them NE away from us...!!! If we bear in the mind the last few winters have been bitterly cold with lots of snow, this has coincided with summers of poor storm numbers...its fair to say IMO that the mid 00s have been a transition between +NAO and -NAO...the 90s and early 00s were robust +NAO years, while now we'er in the grips of -NAO!! Cold winters, poor storm counts in summer...

As I say its just a theory, but it makes sense to me...anyone else? :cc_confused:

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I'm starting to wonder whether it's connected to the North Atlantic Oscillation (NAO)...

That dose make sence, The only thing is Why? why has it changed from what it was... Global warming?

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That dose make sence, The only thing is Why? why has it changed from what it was... Global warming?

Why does El Nino and La Nina occur? Weather and climate is all about balance and cycles...the 90s saw a rapid period of warming across the globe...this is unsustainable and as such we must get cooling to counteract this...I've heard on more than one occasion, the rate of warming across the globe has remained static through the 00s compared to the 80s and 90s...whether this has any merit, or in any way helps answer your question, I don't know I'm afraid.

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Lot of talk about the 'anomolous north westerly' of recent years - I sit on the fence with global warming, but if world temps are increasing, then our rosby wave distribution may be changing along with more heat moving up over the continents. It may be not just co-incidence that russia suffered such a prolonged heatwave last year, and the uk a poor summer - if the 90's/00's put us east of an atlantic trough causing the excessive heat, and now this has tightened up to up to put us in to the west of the trough and the excessive heat moving onto the continent, locking us in to a NW'ly flow in the summer months, then this might explain things -

If man made gw is a myth, then its a combination of global cycles and bad luck that we hacen't had storms for the last few years, and cold winters in the 90's ...

Cheers, Sam

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There may be a flaw in the "stronger weather systems = more storms" argument- as a general rule strong winds are rarely associated with extremes of temperature. Most thundery months feature either slack slow-moving low pressure over the British Isles (e.g. August 2004) or southerly plumes with high pressure to the east and Atlantic systems trying to push in from the west, and in the latter case strong systems often introduce too quick a breakdown to allow many thunderstorms to form.

In 2010, June was poor for thunderstorms because of the dominance of high pressure and lack of forcing mechanisms for thunderstorm development during the hot spell late in the month- low pressure to the west often recurred on GFS runs and then downgraded near the time. July 2010 had low pressure to the NW, high pressure to the south and a persistent tropical maritime airmass- a poor setup for thunderstorms as most precipitation is frontal rather than convective in origin in that setup. In August, the setup was different but again the main issue was a high incidence of frontal precipitation.

2007 and 2009 both had quite active Junes and Julys for thunder activity across the country as a whole, associated mostly with slow moving low pressure and polar maritime airmasses, let down by distinctly thunder-free Augusts.

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Yeah

The original Poster asked for a period of active winter and summer and as recently as 2009 would fit the bill surely :whistling:

Jan and Feb had some good snowy spells including the infamous 1 1/2 Foot of Snow for the London area on Feb 1st 2009, followed up with December 17th & 18th 2009 with 8" in one go including Thundersnow in Essex and Medway Towns.

The whole of 2009 for June and July was very active in the South East with what I would class as at least 3 Severe Thunderstorms (For Uk Standards) on the 17th June, 28th June and the 7th July. Decent sized Hailstones fell with at least 1 possible Supercellular Storm.

In fact I counted 42 Storm days in 2009 (26 in the USA & 16 in the Uk)

Regards

Paul S

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The whole of 2009 for June and July was very active in the South East with what I would class as at least 3 Severe Thunderstorms (For Uk Standards) on the 17th June, 28th June and the 7th July. Decent sized Hailstones fell with at least 1 possible Supercellular Storm.

In fact I counted 42 Storm days in 2009 (26 in the USA & 16 in the Uk)

The only days I can remember were August 2006 probably the biggest storm ive ever seen in the uk one of the trees near tescos extra had to be chopped halfway up because it got struck by lightning and another huge storm on the 28th June 2009 which hit the london region I had bigger then pea sized hail that day as well as a fair few close strikes. There the only two notable storms I can remeber clearly. But i still believe there was deffinatley more vigourous storms in the 90's when I was a young kid I was soo scared of them back then which maybee made them seem more violent but I can remember alot of times being petrified during the night after waking up when a thunderstorm was coming. This year I haven't been woken by any thunder and last year (or year before) I was woken twice. one time during the night I was knackered in the evening and I could see the storms coming but I was too tired to stay awake so went to sleep only to be woken an hour later by a huge crack of thunder (The only one that night). the second time was in the morning from the same 'storm' that set the flat on fire in wembley. I think the earth is just fluctuatng naturally no global warming or anything like that just like the sun goes through low and high solar activity!

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Ok, Im going to fins lots of 2009 charts and compare them to 2010 charts. I'll get back to you :)

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Further back in the archives, 1966 and 1982 had snowy winters followed by notably thundery Junes, although those Junes were also dull and wet for most.

In the last couple of decades 2009, indeed, is probably the best example of a snowy winter followed by an active summer for thunderstorms. There weren't many examples in the 1990s either to be honest, the only years that ran 2009 close for this combination being 1994 and 1996.

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TBH I don't think winter setups have any bearing on thunder in the summer; 1981 I believe was quite a thundery summer as was 1995 in places; they had cold Decembers. 1991 and 1996 after the cold Febs weren't a bad year either, but nor was the snowless 1992.

However I can't remember a year as non-thundery as 2010- only 2 distant rumbles all year, and no lightning at all. Last decent storms I remember here were in June 2007; July 2009 was thundery further east but just rainy all the time here- a horrible month.

Those wretched "Southeast vs. the rest" setups are real thunder-killers; all we tend to get is lots of clouds and frontal precip with no convective activity, as neither hot continental air nor cold northerlies can get here. July 2010 and August 2009 were terrible for this, especially the former with its days on end of cloud, light rain, cool days and warm nights.

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Those wretched "Southeast vs. the rest" setups are real thunder-killers; all we tend to get is lots of clouds and frontal precip with no convective activity, as neither hot continental air nor cold northerlies can get here. July 2010 and August 2009 were terrible for this, especially the former with its days on end of cloud, light rain, cool days and warm nights.

I think that's a good observation- that setup keeps us locked in stable tropical maritime air for long periods and the proximity of high pressure plus fronts rotating around the high's northern periphery adds to the suppression of any kind of convective potential.

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TBH I don't think winter setups have any bearing on thunder in the summer; 1981 I believe was quite a thundery summer as was 1995 in places; they had cold Decembers. 1991 and 1996 after the cold Febs weren't a bad year either, but nor was the snowless 1992.

However I can't remember a year as non-thundery as 2010- only 2 distant rumbles all year, and no lightning at all. Last decent storms I remember here were in June 2007; July 2009 was thundery further east but just rainy all the time here- a horrible month.

Those wretched "Southeast vs. the rest" setups are real thunder-killers; all we tend to get is lots of clouds and frontal precip with no convective activity, as neither hot continental air nor cold northerlies can get here. July 2010 and August 2009 were terrible for this, especially the former with its days on end of cloud, light rain, cool days and warm nights.

It certainly has been relatively storm free around our region the past few years, there was a minor storm a few months back here, honestly completely forgotten the date though? might of been early October? but certainly not been a big storm in a while.

The most memorable storms here in recent years both came on the 19th July (2007 & 2008) with another big storm somepoint in June 2007 (forgot the date?) there was also more minor storm mid April last year early in the morning to but certainly in terms of a porper spanish plume i cant remember the last time there was one, i remember July 2006 came close many times but often had near misses here.

Late June 2005 and 1st May 2005 both were fantastic storm wise though.

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I think that's a good observation- that setup keeps us locked in stable tropical maritime air for long periods and the proximity of high pressure plus fronts rotating around the high's northern periphery adds to the suppression of any kind of convective potential.

Yes I remember someone (might have been yourself?) saying how much they had in common with the winter "Bartlett" setups- the latter rarely if ever allow in either convective polar/arctic maritime or cold continental air. The same airflows that in their summer guises can set off storms. The difference is that winter Bartlett months can sometimes be relatively sunny and dry here, perhaps because the greater pressure gradient (deeper Iceland low) leads to more of the rain emptying out over the Welsh/Scottish mountains, whereas the slacker summer setups seem to spread the cloud all over the W Midlands and northern Britain, often with the rain reaching these parts.

One thing all the summer "thunderstorm setups" charts posted on here have in common is the lack of a large anticyclone over France, even if some show low pressure NW of the UK.

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It probably was me- I've made that comparison in the past. In Tyne and Wear those setups tend to be dry and cloudy with a gusty wind regardless of the time of year, while in Norwich they tend to be dry with some sunshine. Perhaps the difference in the Shrewsbury area might be to do with mid-level convective cloud bubbling up in the summer and flattening into stratocumulus due to the stability of the tropical maritime airmass, although I'm only guessing here.

In parts of East Anglia 1999 had a fairly snowy winter followed by a thundery summer although they were very much the exception rather than the rule (that region picked up a lot of localised snowfall from short-lived northerlies). I mentioned 1994 because that had quite a snowy winter more widely, particularly in eastern Scotland and north-east England, with the south getting some around mid-February, and then the summer had frequent southerly winds and thunderstorms in many parts of the country, especially during the period 24 June-4 August.

Interestingly many of the famous hot dry sunny summers have been remarkably thunder-free, e.g. 1976, 1989 and 1990. I think 1995 was about average over the UK as a whole, with below average activity in June and August but a thundery July. The best examples I can find of hot dry sunny but thundery summers appear to be 1947 and 1975, with the former following the snowiest winter of the twentieth century.

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Very interesting read, thanks.

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Well, i've got a heads up for storms. Had a sefric pass over me on friday with heavy rain and wind anc IC. Verry good so far :)

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Looking at Philip Eden's monthly data, http://www.climate-uk.com/page3.html ,Woodford near Manchester recorded a paltry 2 days of thunder during the whole year.

I personally can only recall 3 days of thunder last year. 2009 wasn't exactly thundery neither, so the last 2 years have been very poor for thunder around here.

What are the stats for your area?

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Only 2 days here, and they were distant rumbles. No storms overhead, and I haven't seen lightning since I think May or June 2009.

The last month that was reasonably thundery was June 2007 (4 or 5 days I think); the following 3 years struggled to manage that many between them.

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In Cleadon in Tyne and Wear, there were 8 thunder-days in 2010 which is about average, but it's noteworthy that 3 of them occurred in November (one thundery shower overnight 8th/9th November in the easterly regime to the north of a deep low taking an unusual south-eastward track, and two thundersnow events on the 28th and 29th).

Cleadon was the exception rather than the rule though. In Norwich it was an exceptionally thunder-free year for this area of the country with thunder on only 6 days, compared with 16 days in 2008 and 12 days in 2009 (the long-term average for most of Norfolk is approximately 15 days, and it is extremely rare for Cleadon to have more days of thunder than Norwich). Looking over the Met Office "lightning strikes" maps for the years for 2001-2010 it is clear that 2010 had less lightning over the UK as a whole than any of the other years.

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There were just 8 days with thunder here, the lowest since at least 2002. Summer only had three of those days, with five consecutive thundersnow days from 28th November - 2nd December making up the rest. Quite an unusual year for more than half of the total to be from cold setups, especially so considering we missed out on the January 2004 thunder event, so it could be well over a decade at least since thundersnow was actually observed here before 2010.

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Only 2 thunder days here which is VERY poor in comparison to previous years (see my signature). Both storms were weak.

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Only 8 days of thunder down here last year which is very poor on we normally get, was least thundery year I think ive ever seen :(

Ah well better luck this year :)

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There was only 6 thunder days here (though there may have been 1 or 2 more while I was away in August) which is well below the average of 15 thunder days.

Out of interest, here is the Met 1971-2000 annual average for days of thunder for the UK:

http://www.metoffice.gov.uk/climate/uk/averages/7100_1km/Thunder_Average_1971-2000_17.gif

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