22nd into 23rd Aug 2011 - Storm/convective Forecast Discussion And Reports

[Harry]

Appears to be yet more cells firing over NW France near the centre of the LP system (based on what I can make out from radar!)

[Norfolk Sheep]

I hope the excitement level hasn't peaked too early

[loopydreamer]

jeez i am SO going to be up all night! This is seriously intense! Look at the cell exploding!! I need a wee!!

[flysurfer]

jeez.. that is a super cell surely..??

[Harry]

I've spoke to someone on Skype earlier, and he was saying it could be a Gust Front.

Is that a Supercell?

Looking at subsequent radar runs the, almost 'ejection' out of the front of the storm was definitely a gust front. However this doesn't account for the entire MCS taking on a bow shape...I'm convinced it was, briefly, a bowing MCS!

As for the Belgium storm I would say it don't 'alf look like supercell given it's fantastic organisation and explosive genesis!! If you're on the E Coast of Kent of even further inland I'd be amazed if you can't see it flashing off in the distance - it's immense and must have cloud tops upwards of 30-40,000ft!

Given the radar info I have available I you couldn't be able to tell if it was a supercell - you need to see if there is a rotating updraught or 'mesocyclone' for it to be a supercell...either way, it must be pummelling those below it. That however IMO has got no chance of reaching our shores...whether there are outflow boundaries associated which fire of storms to the West of it (which I suspect it probably will do given the unstable atmosphere) then game on!

Edited August 22, 2011 by Harry

[Neilsouth]

villaman is right guys! It will intensify definetly!!!!

How can people say this?, these last few years have shown us that things have not gone to plan again and again. I'll be shocked if we get any storms over kent in the early hours

[snow raven]

Oh dear, I was about to go to bed.... now I don't know whether to or not. Don't half wish I had tomorrow off work!

[Nick F]

Convective / Storm forecast - Issued 22/08/2011 23:00

Valid: 23/08/2011 00:00 - 24/08/2011 00:00

Headline: ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FORECAST...

Synopsis

A broad long-wave upper trough extends south from Iceland to the west of the UK, France and Iberia with a cyclonic SW flow across W Europe. Within this flow, a small upper low/trough over Bay of Biscay Monday evening will move NE towards Sern UK, becoming absorbed in the SW flow. At the surface at 18z Mon, shallow low covers France with a warm front lying NE through the English Channel marking the northern limit of warm moist plume over France while developing cold front over W France marks western extent. By 12z Tues, low over France will drift slowly N to be centred near Nord-Pas De Calais, with cold front pushing E across France and wrap around occlusion across SE England.

... S and SE ENGLAND, E ANGLIA ...

Although there are some difference between model output this evening on how the t-storm activity over NW France this evening evolves as it moves towards S and SE England tonight ... it appears there maybe sufficient potential to warrant a SLIGHT risk for severe weather across S and SE England overnight and through Tuesday morning ... mainly for the threat of excessive rainfall.

Coverage of thunderstorms is a little uncertain, given GFS seems rather reluctant to indicate much in the way of CAPE across UK side of the Channel. Nevertheless, upper low moving up from the Brest Penninsula interacting with rather warm moist plume spreading Nwards from France suggests that thunderstorms are possible from 00z to 12z Tuesday before the risk subsided Ewards in the early afternoon. Storms will likely be elevated above a fairly cool boundary layer, but will be capable of producing torrential downpours with a risk of flash flooding, frequent CG lightning and strong wind gusts (up to 40 mph).

Issued by: Nick F - Forecaster for Netweather

[weatherobsuk]

Channel MCS still playing by its own rules and heading NE playing the loops back from a hour earlier. No transitionary component to be seen in the LP circulation yet. Kent in the firing line for this one.

[Dean E]

I'm still keeping a close eye on the front (Yellow area) Intensifying rapidly now...

Meanwhile, Frenchie (I've made her red to stand out, even though you can't miss her!) Is still moving N , NNE with a more organised area still hugging the Northern Coast of France.

But look how far she stretches back... We've still got all that stretching from Nantes... Well as far as the netweather radar goes!

As I speak, a new area has appeared to the East of Nantes!

I expect this to intensify as she hits land. So don't loose hope yet! As this is just the start!

[loopydreamer]

How can people say this?, these last few years have shown us that things have not gone to plan again and again. I'll be shocked if we get any storms over kent in the early hours

yea ok you got me! getting caught up in the moment but i just have a feelin that it will gwt over the water this time! And im not talking about Kent! Im excited for all the guys down on the coast! I have alot of friends there!!

[Harry]

OOOHHHH nice one Nick!!!!

[weatherobsuk]

European rainfall radar loop. Shows the Belgium storm aswell.

http://www.meteox.co.uk/h.aspx?r=&jaar=-3&soort=loop1uur

[loopydreamer]

OOOHHHH nice one Nick!!!!

BRING IT ON!!!!!!

[Buckster]

DDDDEEeecccaayyying

[Harry]

Notice that there are lots of intense cells erupting along the eastern flank of the MCS which will almost certainly merge with Frenchie (although are already technically part of her)....I notice too the sudden NE shift but the low is continuing to hold a more westerly track (IMO) compared to the models earlier!

[snow raven]

There seems to be mixed messages - some are saying its decaying, others are saying we stand a chance...

I dont know whether to stay up or go to bed... Help!

[staplehurst]

There seems to be mixed messages - some are saying its decaying, others are saying we stand a chance...

I dont know whether to stay up or go to bed... Help!

It's definitely decaying, but might invigorate, plus there's plenty more where she came from during the night

[loopydreamer]

DDDDEEeecccaayyying

of couse its losing intensity crossing the channel! We need to be watching it when it meets landfall!

[Nick F]

Well the first MCS crossing the Channel seems to be fizzling out into bog-standard heavy rain, maybe the storms behind it to the SW over Brittany will bring better prospects for later in the night?

[coldfingers]

There seems to be mixed messages - some are saying its decaying, others are saying we stand a chance...

I dont know whether to stay up or go to bed... Help!

Well it looks like I am going to fall between two stools so I am off to bed.

[loopydreamer]

There seems to be mixed messages - some are saying its decaying, others are saying we stand a chance...

I dont know whether to stay up or go to bed... Help!

flippin' eck! i wouldn't be able to sleep if i tried tonite! lol! im too hyped up!!

[Dean E]

Thats got to be a super cell in Belgium... I think it deserves the name 'Explodie' !

If it continues to grow... I was about to say it would be the size of Belgium, too late!

[Harry]

I might head off to bed around midnight if there's no major improvement, then set my alarm and join you around 3am for a checkup...will then prob wake every hour to have a gander

Too many times on nights like this I've watched massive storms moving in until around 4am when they've gone pffft! That said, those situations had different synoptics to this and so the outcome could be totally different!

[Robbie Garrett]

of couse its losing intensity crossing the channel! We need to be watching it when it meets landfall!

Yes however I remember to recall last time I was online, the storms that hit land was only rainfall. Let's just wait and see, 2am if that storms de-intensifying more, call it a night.

What I've learnt with weather is you cannot forecast it, at all - what you can do is go by the METARS, which is the current weather affectively, most accurate weather ever.