22 July 2011 - Storm/convective Forecast, Discussion And Reports

[ZONE 51]

Friday some convective action looks possible! worth checking out as Met Office update mentions heavy showers and even thundery in the SE(latest updates), not sure about elsewhere as not looked around all areas, and not checked data, so i expect to be upgraded for my region at least

[VillagePlank]

There is potential today.

Here's the skew-t from Thurs GFS 18z, for London Heathrow,

Convective cloud cover to at least 6,300m so cloud heights of over 5km giving rise to some 400j/kg CAPE, but still neutral LI, which is -0.

This chart indicates likely thunderstorms (TT=48) in a rather small convective potential environment (K=25, on the boundary to moderate potential)

The trigger should either be surface heating or the rather nice convergence zone setting up from about Cumbria to just East of the Isle of Wight - although the best of this is in the channel, and any storms that form down this line will float SSE,

SE's chances are for an odd air-source - a halfway house between Arctic Maritime and Arctic Continental (I'd plump for Am, in this instance),

which is normally unstable and moist.

Interesting - certainly a radar watching day. My guess for best chances of storms have to be the very West of the SE quadrant - say a triangle of Southampton-Reading-Brighton. Perhaps the more easterly part of that triangle as showers will need to get there in the first place on a slack northerly.

I must note that GFS puts the precipitation to the West of the convergence line not to the East almost certainly related to the 700hPa VV chart,

giving rise to the best showers of the day being home grown and not related to the macro-scale air mass situation. We shall see, I guess - perhaps both regions have (small) chances.

Happy Hunting!

[Coast]

Understandably ESTOFEX have nothing for us today, UKASF have a very low risk:

Forecaster: Dan

Last Updated: 19:39 Thursday, 21st July 2011

Valid: 00:00 Friday, 22nd July 2011 - 23:59 Friday, 22nd July 2011

Areas Affected:

Scottish Borders, N England, E Wales, Midlands, East Anglia, West Country, SE and CS England

Synopsis:

A very negatively-tiled upper trough will be located over much of northern and eastern Europe, whilst an upper ridge continues to build over the North Atlantic and Ireland during the day. A rather slack surface northwesterly airflow will create some marginally unstable conditions across the United Kingdom once again.

Discussion:

Similar to Thursday, convection initiation will rely heavily upon surface heating given a lack of additional external forcing. It is noted that model guidance suggests better amounts of insolation given less cloud cover expected compared to Thursday, and so convection may start earlier in the day. As a result, quite a few scattered showers are expected, some heavy, and given light winds both surface and upper, such showers will be slow moving and may give locally large rainfall totals.

The risk of lightning (and thunder) is very low, especially considering the lack of any detected lightning on Thursday. Currently, the best potential for isolated lightning appears to be associated with the surface trough that is forecast to develop, primarily over the Peak District into the East Midlands with ELT's potentially as low as -20C, but even this risk is quite low.

DLS is more pronounced across Wales and SW England, with up to 40kts possible, spreading into the Midlands later in the afternoon and into the evening. LLS remains rather weak, however, and this combined with weak CAPE (just 200 J/kg) limits the risk of severe weather. At best, a convergence-induced funnel may be possible.

Showers that do develop will slowly decrease in coverage during the evening hours.

SkyWarn have no particular threat highlighted

Severe Weather Risk: Low

Heavy showers for inland Wales, Western and Southern parts of mainland UK. Elsewhere cloudy and cool with occasional light showers.

Cindy still on her way!

A little bit of something on the KO index:

Convective cloud minimal:

CAPE minimal at best:

Shear over Wales

and convergence:

Rain:

Very low possibilities today, but if I had to pick a place I would say Wales (ish!) and the Midlands

[Lynxus]

Some very beefy showers in wales already!

someones gonna get a soaking today.

[TonyH]

Very heavy and prolonged showers this morning with 8mm past hour.

[gpspete]

for those going on holiday this weekend to Cornwall North Devon anywhere facing the Atlantic,

TS Cindy or EXTS Cindy may make for quite a large swell i haven't checked any of the surf models/forecasts but i suspect there may be big surf so watch out if going in the sea, for those more land lubber types, may produce some good wave photo opportunities as the swells hit headlands, harbour walls etc. just do not get too close and put yourself in danger of being swept away if it does happen

oops meant to post this in tropical storm thread never mind,

reference too Coasts comment in his post above "Cindy still on her way!"

[Adi F]

I think Central Southern England may see something from around 3pm into early evening. There are some really nice wind convergence showing up on the charts today I feel its one to watch as it could prove to be an evening up on Portsdown hill.

[Harry]

MetO keen for heavy rain to break out across the SE corner, including London, tonight.

They do have a lightning symbol across E Kent early in the night also.

GFS however, is keen to break out precip but not as heavy as MetO....

Thoughts?

[Coast]

Thoughts?

BBC local weather had 'Thundery Showers' again this morning. I think they just trot that one out now and again to keep us on our toes!

Who is Rachel Mackley BTW?

[Methuselah]

Could be some rumblings in Silicon Valley, later on? :blush:

[VillagePlank]

MetO keen for heavy rain to break out across the SE corner, including London, tonight.

They do have a lightning symbol across E Kent early in the night also.

GFS however, is keen to break out precip but not as heavy as MetO....

Thoughts?

Certainly heavy showers, I'd say - with maybe a 30% chance of a few of them giving us a lightshow ...

[Adi F]

Who is Rachel Mackley BTW?

Why has she got Pyrex dishes shoved up her top? Although Rachel does grab my attention slightly more than Carol Kirkwood!

[Coast]

Sorry to derail the thread, I think she's ex-ITV. I'd like to hear her explanation of a warm front moving in

Back on topic, looks like convective rain later this afternoon in the SE over me!

[Adi F]

She is beautiful, that dress really does do her justice, why is she not on my tv?

Right back on topic or more to the point back to doing some work!

[TheToastPeople]

the met has posted somthing for me today

Tonight:Scattered heavy and thundery showers this evening, especially across Cambridgeshire and Bedfordshire initially and then later Essex.

Lying laminate floors why get my hopes up like that?

[Sprites]

Why has she got Pyrex dishes shoved up her top? Although Rachel does grab my attention slightly more than Carol Kirkwood!

A couple of features to watch out for there, a new forecast system being developed with built-in satellite dishes.

[Costa Del Fal]

Just like yesterday I cannot see any Thundery potential today. Very little Cape, poor lapse rates, poor Equilibrium level temperature etc. However, heavy showers quite likely especially through Birmingham, London, Kent/Sussex this evening imo.

My hotspot for storms today: Nowhere. :lol:

[Sprites]

Just like yesterday I cannot see any Thundery potential today. Very little Cape, poor lapse rates, poor Equilibrium level temperature etc. However, heavy showers quite likely especially through Birmingham, London, Kent/Sussex this evening imo.

My hotspot for storms today: Nowhere. :lol:

I agree but still a chance of a funnel cloud developing in southern coastal areas..

[Adi F]

Coast just to help your warm front move

[Biggin]

Well thats brightened up my day here. Fingers crossed for heavy showers

[Harry]

Bloody stalkers lol

[Purplepixii]

<----- desperately seeking a hot male forecaster

Anyway, back on topic, bloomin' warm here in the sun with little breeeze (making it a good day for flutterbies in my garden). Weather station currently says 21.4oC & 53% humidity

[Guest Quantumsnow]

Ey-up lads what's happened to the storm thread? I might have to deploy that 'Schafernaker' half naked front cover pic to cool things down a bit

Better make it on topic, few convective type clouds here, but nothing too noteworthy.

[Lauren]

What's with the pictures of the girl?

[Andy Bown]

The showery area across Wales and the West Country seems to be starting to edge slowly East while the showers continue to

run slowly from NNW-SSE along the trough.

What's with the pictures of the girl?

Don't know, not sure at all. Seems ridiculously off topic and unneccessary to me.