UK Convective General Discussion & Forecasts

[Coast]

Getting into September soon and what are the prospects for any storms?

[VillagePlank]

In Rochester thunder had been observed, but no lightning seen ... *sigh*

[Coast]

First tentative signs coming in for something next Monday afternoon with a bit of luck:

[Harry]

Oooh oooh ooh sir sir, pick me pick me!!!

GFS throwing us in the SE a possible end of summer storm life line Saturday night into Sunday morning...builds up CAPE nicely over France (region of circa 1,500-2000 CAPE) with LIs around -4 to -7...precip charts keen to break out storms merging to form a nice multicell/MCS system which drifts across the SE.

3 days out, likely to develop eastern swerve....nevertheless a pleasant development IMO one in which looked likely to show itself given the favourable synoptics....should hopefully generate some discussion anyway

[Coast]

GFS throwing us in the SE a possible end of summer storm life line Saturday night into Sunday morning...builds up CAPE nicely over France (region of circa 1,500-2000 CAPE) with LIs around -4 to -7...precip charts keen to break out storms merging to form a nice multicell/MCS system which drifts across the SE.

That's just crept in on this mornings run as I was looking at next Monday as the only sign of interest!

Knowing our luck this will all end up going East into Belgium and Holland. But at least two up and coming chances now according to GFS, here's a starter for 10:

At this point in time, the RASP is showing that it never quite makes it to us:

Dew points don't look too bad though

Kent clipper again?

[Sprites]

As its getting towards the end of summer, im hoping for some autumn squalls or active cold fronts, these can be good for funnels, hail, and photogenic structure, and may a low-topped supercell..

[Lancashire Lass]

Possibly a bit of interest for those of us in the NW for next week:

UK Outlook for Monday 5 Sep 2011 to Wednesday 14 Sep 2011:

The unsettled weather is expected to continue throughout much of next week with the northwest likely to see the bulk of the wetter and windier weather, with gales also possible in exposed areas of the north and west. The rain will be heavy at times, with risk of hail and thunder being mixed in with the heaviest showers.Some drier and brighter conditions though will develop in between the spells of rain, especially towards southeastern parts of the UK. Temperatures are expected to be a little below normal but southeastern parts may reach near normal at times. Staying unsettled as we head into the weekend and beyond with further spells of rain or showers but also some brighter and drier spells, best of which towards the south and east.

http://www.metoffice.gov.uk/weather/uk/nw/nw_forecast_weather.html

[Costa Del Fal]

18z GFS is pretty good for SW, Wales, Midlands and other Western areas on Monday with very good lapse rates, and some LLShear and a modest amount of Cape/LI. Will probably change further but should be something to look forward to. The Easterly shunt for this weekend is well under way regarding convective potential in the SE so that one looks like it might be nearly in the bin already but again time for change but as we know, its unlikely it will ever be in favour of us!

Edited August 31, 2011 by Blizzards

[Coast]

Saturday night still looking like an extreme SE (possibly EA) event at best:

[Harry]

Looking poor yet again!

As ever, we see a northward progression of warm unstable air over the past couple of days, shunting east as it approaches us....look at the estofex chart for today! Bit sickening really....look at the sudden eastern shift in the Level 1 zone.....

[Paul Sherman]

Looking like another Poor Summer yet again Harry - Probably the 4th out of the last 5 years and even the other one was not a match on the 1980's & 1990's storms we used to get.

You need to get yer butt over to Arizona if it is Lightning you want, 2 of the days had over 46,000 and 34,000 Lightning Strikes just in 2 days

I have given up in this country now as I really think a shift happened with the pattern in the 90's to affect our weather and I am sticking by that

[Stuart]

I had 5 storms this year so I am happy

[Coast]

I have given up in this country now as I really think a shift happened with the pattern in the 90's to affect our weather

look at the sudden eastern shift in the Level 1 zone.....

Time to move to NW France or Belgium then?

[Stuart]

think we all sould coast

[Nick F]

Seems to be a little uncertainty (as usual with convective potential) for this weekend, but it looks like warm moist Tm air gets dragged in across England and Wales on Saturday, ahead of cold front in the west, which *may* destabilise towards the SE - 00z and to a lesser extent 06z GFS paints some CAPE across SE England and E Anglia Saturday afternoon - so potential there for an isolated storm if the likely cap can be broken.

Then on Sunday, the cold front looks to sweep east across England and Wales, so potential for embedded storms along the front - before fresher more stable conditions follow from the west.

Though it could all come to nothing with the near continent taking the lion's share of any storms.

[Harry]

Time to move to NW France or Belgium then?

Oh dear...not sure NW France does THAT much better than us? I know I hate pedantry too!

Nah I've been Belgium and few times and it's not the cheeriest of countries IMO.

[Purplepixii]

I have given up in this country now as I really think a shift happened with the pattern in the 90's to affect our weather and I am sticking by that

In your opinion Paul what caused this shift?

[Coast]

Oh dear...not sure NW France does THAT much better than us? I know I hate pedantry too!

Nah I've been Belgium and few times and it's not the cheeriest of countries IMO.

Sorry NE!!!!!

In your opinion Paul what caused this shift?

The weather hasn't shifted, it's just that the UK has drifted 150 miles too far West on a tectonic plate.....

Only bonus is, in 23 years time we will all be on the East coast of the USA.....

[Harry]

Sorry NE!!!!! The weather hasn't shifted, it's just that the UK has drifted 150 miles too far West on a tectonic plate..... Only bonus is, in 23 years time we will all be on the East coast of the USA.....

Sorry again with the pedantry, but the Mid Atlantic Ridge is seeing to it we're getting further from the Yanks day by day...sadly, we don't seem to be moving any nearer continental Europe...if only we could have an intense ice age for a year or two, which restablished the poles and allowed the channel to sink such that there's no Channel now that'd be ideal!

GFS 06z still very keen to keep action across the continent....daylight bloody robbery yet again!!

Edited September 1, 2011 by Harry

[Paul Sherman]

Lol @ Coast!

PurplePixi I have not got the foggiest, but something seems to have happened in the last 10-15 years. We used the get at least 4-5 Spanish Plumes in a summer with the Middle of July to the Middle of September being very good as the SST's in the Channel would have no effect on the Storms moving North East out of Biscay. Now they either kill them stone dead or they get steered towards the Dover Straights and up over Benelux.

It comes to something when you have to travel 5,000 Miles for your Lightning Fix every year!

Sorry again with the pedantry, but the Mid Atlantic Ridge is seeing to it we're getting further from the Yanks day by day...sadly, we don't seem to be moving any nearer continental Europe...if only we could have an intense ice age for a year or two, which restablished the poles and allowed the channel to sink such that there's no Channel now that'd be ideal!

GFS 06z still very keen to keep action across the continent....daylight bloody robbery yet again!!

Or we could all club together and employ oddjit and Bodgit to Cement over the Channel to allow those Continental Storms to affect us

[Lauren]

What a lovely day today and lots of fluffy CU about. makes a change from the cold grey days we've had recently.

[Costa Del Fal]

Monday still looking quite interesting for the SW, Wales, The Midlands and into Northern Parts.

[Coast]

Sorry again with the pedantry

Pedant! I think it's all down to Government cutbacks then - no hang on, lets not go down that route

I've had a dig for some info on the decline of Tstorms in the UK and whilst I haven't found anything conclusive yet, I have stumbled across a couple of things of minor interest:

The Earth sees about 760 thunderstorms every hour, scientists have calculated.

The figure, unveiled at the European Geosciences Union meeting in Vienna, is substantially lower than numbers that have been used for nearly a century. The new research uses a global network of monitoring stations that detect the electromagnetic pulses produced by major bolts of lightning. It confirms that thunderstorms are mainly a tropical phenomenon - and the Congo basin is the global hotspot.

Thunderstorms also track the passage of sunlight across the world, with sunny conditions producing greater convection in the air. "The monitoring stations might miss some bolts of lightning, but we think we're getting the big ones - and that's enough to tell you where the thunderstorms are," said Colin Price, head of the Geophysics and Planetary Sciences department at Tel Aviv University in Israel. "And so with this global network we're able to improve on numbers that have been in standard use since the 1920s."

The first attempt to estimate thunderstorm numbers is thought to have been made by CEP Brooks in 1925. At that time, it was customary for weather stations to note days when thunderstorms occurred nearby. Collecting records where he could, the British climatologist calculated there were around 1,800 per hour on average across the world. But his research suffered from incomplete data and mistaken assumptions - including that storms were equally distributed over land and sea, whereas the vast majority occur over land.

In the 1950s, OH Gish and GR Wait flew over the top of 21 thunderstorms in the US in aeroplanes carrying equipment capable of measuring voltages and currents in the air. Extending their readings to the rest of the world, they came up with a global figure of 2,000-3,600 per year. More recently, satellites have been deployed - but they do not see the whole world. The new research uses a completely different technique, with more than 40 stations around the world geared up to detect electromagnetic pulses produced by strong lightning bolts.

Triangulating from groups of stations enables the World Wide Lightning Location Network (wwlln.net) to pinpoint flashes. When they are clustered, a computer algorithm is deployed to assign flashes to their separate parent storms. Analysing this data for September 2010 produced the average hourly figure of 760. Each continent shows peaks during its daytime - and globally, the peak time is around noon GMT. Thunderstorms cluster in the centre of continents in the tropics, with the Congo basin standing out.

"That's perhaps because it's drier there than in the Amazon, for example - thunderstorms seem to form more easily in drier conditions," Dr Price told BBC News. The network is looking to add new observation points to improve results, and recently initiated a programme to detect explosive volcanic eruptions via the lightning flashes that occur in the ascending plumes of hot ash.

http://www.bbc.co.uk...onment-12991483

So going on the wwlin.net site, you do get the density for the whole planet for the previous day:

Unfortunately our one, Sheffield is currently offline.

Below is the average yearly counts of lightning flashes per square kilometer based on data collected by NASA satellites between 1995 and 2002. Places where less than 1 flash occurred (on average) each year are gray or light purple. The places with the largest number of lightning strikes are deep red:

The following is a World lightning map by NASA shows the geographic distribution of lightning. Areas of highest activity are shown in orange, red, brown, and black. Areas of low activity are white, gray, purple and blue.Lightning activity is lowest over the oceans and polar areas.

[staplehurst]

Fully agree with Paul here, and it is something I'd hoped to explore for my dissertation.

(the changing weather pattern that is, not the cementing of the Channel )

Edited September 1, 2011 by staplehurst

[Coast]

I'm not sure what data these people are using, but http://web2.airmail....b1/european.htm reckon:

TORRO have this historical data:

Average number of days with "thunder heard", 1971- 2000

15-19 Days 10-14 Days 5-9 Days Under 5 Days

©TORRO 2006