Uk Convective General Discussion & Forecasts, 4th August 2012>

[Methuselah]

Do you know what I haven't seen for a long time? Those night-time storms that flash blue-white lightning for hour after hour...Where have they gone!

[Evening thunder]

The FAX chart does look appealing for storms in many places including south-west England, with convergence likely over Devon.

I agree that storm lovers in SW England have had a pretty rotten time of it over the last two years. On average (over the period 1981-2010) Exeter is about as thunder-prone as Newcastle, but that certainly hasn't been true recently!

Yeah has been a pretty poor show I think, we have managed one decent night time storm in both 2011 and 2012, which is more than some people I suppose, though a lack of daytime events where you can see the cloud structure and any torrential rain at my location this year, with a couple in April 2011 nearby giving rumbles of thunder though but not overhead.

In other news I note the 12z GFS downgrades the CAPE in the SW on Sunday to zero - quelle surprise!

[legritter]

well ,RYBRIS PONCE ,we could be getting some overnight storms late sat or sunnight .all depends on the time of arrival and the synoptic situation .we will have to wait and see .but the potential is there .we dont necessarily need big high temperatures ,just need to get the right mix of elements ,but with a trough setting up the potential is definately there .i have not yet checked cape ,energy etc but i can remember from years ago that in the expected synoptic situation this weekend embedded thunder storms and heavy rain can very possibly be expected . as george the second said ,3 warm days then a thunder storm .we;ll see . anyhow tonights fax will be helpfull .cheers legritter

[Costa Del Fal]

The downgrades have well and truly begun. Sunday doesnt look too much now, maybe a few storms but no more really imo. Next week looks like going back to square 1 too.

[Chris K]

Déjà vu by the looks of things. It's been downgrading each and every run for the past 2 days. It has to be expected by now.

I'm not saying nothing will happen though, as there is still 2 days to go for details on the various different factors to firm up. I'm just not expecting anything so that I save myself from replacing my screen every time its a non-event.

After all, I had a storm last weekend. That's it now for a few more years

Slightly off-topic - but here is a couple of Met Office fax charts for 9&10 May 2008. This produced big thunderstorms for the Bristol area, as well as parts of Wales, some western areas of the Midlands and C/S England. I think I recall it lasting at least 3 hours where I live because the front & troughs were slow moving & stalling over us. Spectacular lightning display as it got dark.

If there's ever a setup like this again I'll wet myself. It looks quite complex so everything must of been just right for the time...

Edited August 9, 2012 by Chris K

[Supacell]

We live 7 miles north of Derby and have seen 8 storms so far this year.Apparently Derby had one last sunday afternoon and yet we had nothing!.Just goes to show how hit and miss storms can be!!.Not had a night time storm here for around 3 years.The early 90's seemed best for those,especially 1993 when my Treehouse got struck one night!!.

You actually live about a mile away from where i lived up to my early 20's - you must know Little Eaton? My parents live at Heage so not far away from you either, but my mother is prone to a little exaggeration at times so 8 storms may be closer the mark

I remember the early 90's when i would sit and watch lightning out of my bedroom window for hours. It just doesn't seem to happen like that anymore.

Onto this weekend - latest GFS not too good for Sunday's potential (at least not as good as it was) but its still a long way off. With southerly winds setting up though there could be a chance at some point next week for something good.

[Methuselah]

The downgrades have well and truly begun. Sunday doesnt look too much now, maybe a few storms but no more really imo. Next week looks like going back to square 1 too.

Come on, peeps? Don't go writing everything off, on the back of one or two model runs...It may indeed (it usually does anyway) all go pear-shaped in the end but, then again, it might not...Let's see what the overnight runs come-up with?

[A.J]

Come on, peeps? Don't go writing everything off, on the back of one or two model runs...It may indeed (it usually does anyway) all go pear-shaped in the end but, then again, it might not...Let's see what the overnight runs come-up with?

Pete, I also think that some posters are getting too hung up on SBCAPE & LI charts TBH....I would expect elevated convection to be the main player on sunday, and a looking at the lightningwizard & NW charts, then the parameters for Sunday morning/afternoon look rather good for south western & western regions

[Eye to the sky]

You actually live about a mile away from where i lived up to my early 20's - you must know Little Eaton? My parents live at Heage so not far away from you either, but my mother is prone to a little exaggeration at times so 8 storms may be closer the mark

I remember the early 90's when i would sit and watch lightning out of my bedroom window for hours. It just doesn't seem to happen like that anymore.

Onto this weekend - latest GFS not too good for Sunday's potential (at least not as good as it was) but its still a long way off. With southerly winds setting up though there could be a chance at some point next week for something good.

.Yeah I know Little Eaton well,I drive through it every day returning from work.My Treehouse was in a field near Lower Kilburn in a huge Oak Tree.You can still see the Stump with a huge split through the middle of it.What was left of the tree was cut down 2days after it was struck as it became quite an attraction.I think it was deemed unsafe!.

[Minimace]

Saw this at the weekend, just wondering what you lot think if might be?

http://i311.photobucket.com/albums/kk472/minimace10000/eb06917d.jpg

[Chris W]

Lookslike an upgrade on the 18z. CAPE through Saturday night over the SW spreading and intensifying northwards through the day on Sunday including a peak in North Wales close to what it was showing yesterday in the chart I posted. Again, don't know how the other parameters are shaping up but whilst the main areas have shifted around a bit there's been a pretty consistent indication of good potential energy-wise for many areas this Sunday in my opinion.

Edited August 9, 2012 by Chris W

[Sprites]

Saw this at the weekend, just wondering what you lot think if might be?

http://i311.photobucket.com/albums/kk472/minimace10000/eb06917d.jpg

looks similar to tail cloud, moist air being lifted from the rain area, or a low outflow feature if the main system is moving left to right.

[Nick F]

Current ridge we're under drifts away east over next 48 hrs to allow in a short-wave trough to move in across the SW Saturday night, which then continues NE across the UK on Sunday. The trough will engage plume of fairly warm and moist air advecting north from Biscay/France, so looks likely that a few elevated storms could erupt across SW England/SW Wales Saturday night, then as the shortwave continues NE, showers/storms becoming more widespread on Sunday across England and Wales (perhaps becoming surface-based), though probably scattered with some places escaping with a dry day. Vertical shear looks fairly weak - so severe weather risk low, though mid to upper winds pick up with passage of trough, so some organisation into multicells or perhaps even a MCS possible, with risk of hail and gusty winds.

Unstable warm and humid S'erly flow on Monday, so despite weak vertical shear again fairly strong mid-upper winds could allow multicell storm clusters with risk of hail and gusty winds. Looks like plenty of convective potential next week.

UKMet fax looks nice Sat night:

[Coast]

GFS doesn't have it covering such a big area as before, but the movement NE can be seen in these simple charts:

Monday looks encouraging:

[gottolovethisweather]

Current ridge we're under drifts away east over next 48 hrs to allow in a short-wave trough to move in across the SW Saturday night, which then continues NE across the UK on Sunday. The trough will engage plume of fairly warm and moist air advecting north from Biscay/France, so looks likely that a few elevated storms could erupt across SW England/SW Wales Saturday night, then as the shortwave continues NE, showers/storms becoming more widespread on Sunday across England and Wales (perhaps becoming surface-based), though probably scattered with some places escaping with a dry day. Vertical shear looks fairly weak - so severe weather risk low, though mid to upper winds pick up with passage of trough, so some organisation into multicells or perhaps even a MCS possible, with risk of hail and gusty winds.

Unstable warm and humid S'erly flow on Monday, so despite weak vertical shear again fairly strong mid-upper winds could allow multicell storm clusters with risk of hail and gusty winds. Looks like plenty of convective potential next week.

UKMet fax looks nice Sat night:

As that Fax chart looks similar to the one I posted a couple of days ago and also rather like Chris K's input above, it does suggest the MetO are still favouring a Thundery type outbreak at this stage. In spite of this, there may well be a fair few disappointed folk in here judging by the latest outputs. I'm not personally pleased as my location doesn't look like being centre stage for the overnight show but things will firm up nearer the time.

Stunning clear skies here for now and if that continues into Saturday/Sunday, the heat should play its own part IMHO too.

Having said that, the advice from others is absolutely spot on though, let's get closer to the date before deciding whether it is another bust or not.

Edited August 10, 2012 by gottolovethisweather

[Stuart]

well after the let down here for storms last weekend i hopeing for storms

[legritter]

first of all ,POTENTIAL FOR HVY RAIN AND SOME STORMS still on the cards . how late on sat trough arrives is critical also tomorrows temperatures humidity cape etc etc angle of trough ,speed of trough .so any forecast in this synoptic setup i wouldnt want to put any locations under any definate detail at the moment . tonights met office fax [human produced ] should give us storm lovers some clues .we do have on our side for night time storm lovers a bit longer of darkness compared to say end of june .anyhow im of to dentist then do some grass cutting before the monsooon arrives

[AWD]

Re: Early/Preliminary thoughts on the breakdown to the warm/humid conditions this weekend.

Early stages yet, but there is a slight trend I have noticed about the prospect of thundery activity this weekend, more especially Sunday, IMO.

If we look at the below charts, the risk seems to have moved North rather than East on recent runs:

Also shown clearly here:

The above showing a general trend northwards rather than Eastwards of the potential thundery activity. Remember early this week the GFS had some decent cape/LI values to the North West/North Wales, before moving these values south to the South/South West/West Country. Well, it seems to have reverted back to its original thoughts and moved the best instability further north again, albeit less pronounced with modest Cape/LI being shown now.

This from Matt Hugo:

High resolution (10KM) model signaling a decent convective 'line' from NW Eng down into the Midlands between 3pm and 6pm on Sun.

Thermal Plume shown nicely here, stretching from London to the North West.

And seeing as Coast hasn't posted this morning , here are a few other early charts, all showing the North West to be at greatest risk IMO.

Come Sunday afternoon, all these charts show a decent risk of storms for North West areas, North Midlands.

However, I cant rule out storms for South West England, South Wales and South/West Midlands either. Not just because its early days, but because IMO, the breakdown has been brought forward a little, thus now arriving overnight into South West England and early morning else where across the South and West, therefore looking at the GFS Cape/LI charts arent the best idea for thundery action this time of day, as I believe SB Cape is a better indicator for night storms. This also might explain the downgrades looking at the raw GFS output, simply because the timing of the breakdown has changed from what it was earlier this week.

If we look at the SB Cape for 09z Sunday, it does show a modest amount across the South West/South Wales

Compared to this at the same time

Other charts/factors also show a risk for the South West quarter too, just early morning rather than later in the day.

Here are the FAX charts for Sunday

Showing a Thundery trough moving up from the SW over South West England initially before moving into the North/North West.

I was at Bristol International Balloon Fiesta last night and didnt get back until very late, with a slight hangover now too, so apologies if some of this seems rather odd or I have explained it rather confusingly. I guess the point I am trying to make is, even though the basic CApe/LI values are rather up and down at the moment, with the South/South West seemingly getting downgraded, its all to do with the timing of the trough IMO. If it arrives overnight/early morning, then by just looking at the Raw Cape values from the GFS, you might get the wrong picture. The potential is still there for the Western side of the UK, first the South West then moving into the North West Sunday afternoon.

Changes are still likely right up to T+6 on this sort of scenario. This will be an event I will watch closely, but admittedly, I cant get overly confident of anything happening here just yet, been so many damb squibs here in past years, it makes it sooooooo easy to find ways of how it can all go wrong, and it still can too, so caution is needed.

As a side for now, the HiRlam doesn't show much PPN activity at at compared to the GFS for Sunday.

But we can look more into this tonight and tomorrow, as well as equally good potential for Monday in some places.

Edited August 10, 2012 by Active Weather Dude

[Vince Coombes]

Another SE bust then , why dont they get storms anymore , its always up North ???

aylesbury

bucks

[Gavin P]

Hi all,

I've done a video examining the chance of a thundery Sunday;

http://gavsweathervids.com/

From what I can see we definately have a risk of thundery showers or thunderstorms on Sunday - More especially for Wales, the Midlands and Northern England, but I'm not sure I'm seeing much evidence of a severe or classic spell of thundery weather? That said, we haven't got the Hi-Res models in for Sunday yet, so it remains to be seen which way they jump when we get them in later today and tomorrow.

Edited August 10, 2012 by Gavin P

[Coast]

Well, looks like us far South Easterners are going to have to make do with the weather before the breakdown! Still a lovely weekend in prospect and I can't say I've had enough storms so far this year to remember what a good one is like anyway!!!

[Lynxus]

Well, looks like us far South Easterners are going to have to make do with the weather before the breakdown! Still a lovely weekend in prospect and I can't say I've had enough storms so far this year to remember what a good one is like anyway!!!

Its a start here! Might even get a storm finally lol... But lets just wait until it doesnt happen anyway

[AWD]

Looks like the GFS is modelling the trough to come in from WSW and therefore missing out the South West and instead going into South West Wales and heading NE from there.

[fromey]

Looks like the GFS is modelling the trough to come in from WSW and therefore missing out the South West and instead going into South West Wales and heading NE from there.

please tell me your joking!!

[twister2005]

Met office south west forecast saying thunder ??!!!