UK Convective General Discussion & Forecasts - June 6th 2012>

[swash]

Sun is trying to break through in Epping, but it's got a lot of work to do!

[Bobby]

Some fairly intense cells have started to pop up over SW England (near Exeter especially) and across Wales. Some threatening looking skies out the window in fact.

[Aaron]

LOL Met office now predicting up to three inches of rain in parts of the South East.

Yeah, because that rain is just sitting over the SE not moving at all.. actually it's moving towards the SW.

[MP-R]

Funny how the rain is moving west as the trough is moving east. Just drizzle here at present and feel cold but some beefier showers out west.

[DubWeatherAddict]

Morning all and as we try to avert a water disaster here at work, I'll take 5 mins out to round up what other sites are saying about today's convective possibilities and that all important rain due here in the SE:

ESTOFEX, TORRO and UKASF have nothing but SkyWarn are on the case with this forecast:

21st OWS have something just skimming the SE coast:

GFS has the centre of the low over the SE midday and some very small amounts of CAPE :

Shear over Hants and Dorset:

Here's that rain!!!

Spout index looking strong in the SE coastal area:

A lot of moisture up there on the West side of the low:

So maybe a chance of a few isolated thundery spells today, but the rain is the big feature and quite a worry:

Shear and spout index on the ball today!

Tornado officially touched down in Donegal just 2 hours ago!. And heres me off to America tomorrow to chase for these?!!! hahaha

All photos here. https://www.facebook.com/media/set/?set=a.10150841451177100.390870.671047099&type=1

[Marie]

LOL Met office now predicting up to three inches of rain in parts of the South East.

I have had 2 inches of rain in the last 24 hours and its still raining so i wouldnt be surprised if we reach 3 inches possibly more

[SimonP]

Today's ESTOFEX forecast has a chunk of the south covered by a 15-% t-storm risk area. Marginal, to say the least: http://www.estofex.o...ormforecast.xml

BTW, there will be no UKASF forecasts until the 21st June, due to forecasters chasing in the US...

[TonyH]

Quite a nasty cell moving here from the north in view of the webcam now.

[VillagePlank]

It will be interesting to see what emerges from this afternoon.

Here's the skew-T for Heathrow,

Now with positive LI and not much CAPE listed for 15z today, one might be tempted to say - to hell with it, nothing interesting is going to happen today.

However .... look at the KI index (which, to my mind is a much more reliable indicator of convectibility (new word, for this year!) for a much larger proportion of the atmopshere; it's 30 - which isn't just moderately convective, it's moderately convective heading off to a high convective atmosphere.

Similarly, look at the TT index (Total Totals) - this gives a clue about the severity and spread of storms should they occur. 50 is right at the high end of probable thunderstorms, and ever so slightly lower than scattered severe storms; where we define severe storms as frequent CG etc etc with some added extras.

So, what will happen in the absence of favourable CAPE and LI?

Worth watching methinks.

Edited June 11, 2012 by Boar Wrinklestorm

[Coast]

So, what will happen in the absence of favourable CAPE and LI?

Rain I guess, there already seems to be far too much of it in the SE and its getting serious:

http://forum.netweat...n-june-7th-2012

[DanN]

Similarly, look at the TT index (Total Totals) - this gives a clue about the severity and spread of storms should they occur. 50 is right at the high end of probable thunderstorms, and ever so slightly lower than scattered severe storms; where we define severe storms as frequent CG etc etc with some added extras.

Good explanation of the TT index on here...

http://www.theweatherprediction.com/habyhints/302/

Doesn't take into consideration CAPE and shear directly, so I guess it's not always relevant...or to be trusted :-) However, NMM does show some marginal CAPE on the south coast this afternoon with lapse rates just touching on the negative side. Worth keeping an eye on I guess.

[Neilsouth]

Been a nice day today, all that constant flooding rain went to the west lol

Storms? maybe, they have to get something right

[Coast]

Been a nice day today, all that constant flooding rain went to the west lol

Not so funny for those that have been flooded out though eh Neil?

[Neilsouth]

Not so funny for those that have been flooded out though eh Neil?

Don't know I don't have a house on a flood plain or near a river

[Coast]

Thanks anyway for your insight and concern for other members who have lost property this afternoon.

[VillagePlank]

Alas, sferics now showing in Kent, E Sussex and W Sussex; I presume where the rain had stopped and it brightemed up a bit, the surface temp rose and triggered the damn things.

Not in the mood for ramping anymore given the misery that this is likely to cause

Stay safe peeps.

Edited June 11, 2012 by Boar Wrinklestorm

[Coast]

Alas, sferics now showing in Kent, E Sussex and W Sussex; I presume where the rain had stopped and it brightemed up a bit, the surface temp rose and triggered the damn things.

A few more kicking off near the Belgium coast now as well, would be nice to enjoy a good thunderstorm tonight without worrying about all the accompanying possible rain:

NW ATD radar has some action in Devon too:

http://www.netweathe...lightning;sess=

[Neilsouth]

Still no storms here very poor forecasting for east kent today -> this afternoon

Edited June 11, 2012 by Victor Meldrew

[Aaron]

One station in Bognor Regis has had over 110mm of rain in 24 hours (over the course of two days).. that is insane.

[GadgetWeatherFreak]

Todays been so hazy and with dark menacing skies, i actually witnessed what appeared to be moisture/mist being sucked into the dark clouds earlier, hadnt seen that for a while, very black clouds now, hopIng for lots of action soon

[Bluebreezer54]

Been a nice day today, all that constant flooding rain went to the west lol

If there was an award for the most insensitive post of the day, this one would be right up there, along with your following one. Poor form in my opinion.

[ZONE 51]

I have created a warning map for todays risks, We have Ireland,Wales and Southwest England for the focus on the thunderstorms today.

Must say it's looking like some active stuff in those zones! also to note is heavy rain across some S/SE areas as i type, this around for some time, so some more flooding is likely.

I made the map using 3 ppn models, CAPE/Lifted Index, Surface winds/ other, to give you an idea i am to show you an early stage in my map making!

This is the precipitation stage from the above map(below)

Further throught the week we have more downpours and thunderstorms, and some widespread.

We also have the risk of an Atlantic storm on the way.

Edited June 12, 2012 by ElectricSnowStorm

[Coast]

With so many UK based storm sites down on staff due to chasing in the States, its down to ESTOFEX today to give us their thoughts on convective possibilities. A busy day in Europe and they have some of the UK featured:

Storm Forecast

Valid: Tue 12 Jun 2012 06:00 to Wed 13 Jun 2012 06:00 UTC

Issued: Mon 11 Jun 2012 23:17

Forecaster: TUSCHY

A level 1 was issued for parts of N-Germany and NE Netherlands mainly for heavy to locally excessive rainfall amounts.

SYNOPSIS

Given the magnitude of the broad upper trough over most of Europe, the calculated blocking index reveals quite low numbers, mainly caused by an overall smooth height gradient over most of the E-Atlantic and Europe and weak geopotential height minima in the trough itself. Nevertheless, ongoing blocking pattern assists in another round of active weather (convective-wise) for parts of C/E-Europe. Of main interest will be short-waves, which round the main trough and race to the E/NE. One is currently centered over S-France, fostered by a sharp moisture gradient along its tip (WV channel) and a structuring warm conveyor belt ahead (11th June, 21 Z). This feature exits NE-Italy until noon and lifts out to the NE thereafter (with a decrease in strength). Another impulse exits Belarus during the morning hours with a rapid progression to the north. This evolution assists in a broadening of the zone of CAPE/shear overlap and hence for an extensive area with organized DMC.

At the surface, a very complex surface pattern has evolved with latest map analysis placing a well defined wavy boundary over Switzerland and Austria, arching more towards SE Czech Republic further east, where one of numerous weak meso-beta scale lows is analyzed (11th June, 21Z). This quasi-stationary boundary oscillates north and south, modulated by enhanced segments of DMC and adjacent southward surging outflows. Arrival of a strong mid-layer impulse finally transforms that boundary in a gradually consolidating and NE ward moving warm front over E-Austria and Hungary around noon and a southbound moving cold front from C-Italy to the east (although near parallel alignment to the background flow keeps propagation speed to the south on the lower-end side). To pinpoint any developing surface depression is hard with the most likely development from E-Austria to the NE. However, an extensive W-E aligned surface pressure channel extends from W-Italy all the way to SE-Poland, where variable model outputs hint on numerous weak LL waves/depression in the prevailing SW-erly flow. Given that high and coarse resolved models all show the same surface pressure channel, confidence increases somewhat, that another baroclinic zone over Switzerland, Austria and S-Germany evolves during the forecast, as easterly flow to the north of the pressure channel advects moisture to the west.

... NE France, Benelux and parts of Germany ...

Adequate BL moisture beneath 500 hPa temperature of at or below (aob) -20 °C result in widespread SBCAPE of 500 to 1000 J/kg. Despite weak shear (aob 10 m/s), this amount of instability, forecast diffluent flow aloft and up to 150 J/kg LL CAPE may assist in a few strong to isolated severe thunderstorms with an isolated large hail and strong wind gust event. Given active convection and aforementioned LL CAPE, a 'mesoscale accident' can't be ruled out and hence an isolated tornado event will be mentioned. Given a persistent signal of a weak surface low over E-Germany in WRF/GFS/EZ, concerns exists that excessive rainfall amounts may become possible due to slow moving storms, which travel along the W-E aligned theta-e axis (from NE Germany to the Netherlands). Also, ageostrophic deflection of the wind mainly within the 1 to 3 km layer may result in a temporarily more organized multicell event. Reflecting that risk in the probability scheme, we issued a confined level 1 area. Thunderstorms gradually decay after sunset.

... Rest of the lightning areas ...

Mainly sub-severe storms are forecast beneath the upper trough. Activity will be daytime driven with stronger cells containing marginal hail. The activity diminishes after sunset.

Here's some hints and pointers to anything convective for today:

21st OWS site down at the moment, so here's another aviation indicator:

GFS has some CAPE out in Southern Ireland and a smidgen in the SW:

Plenty more rain out West too:

Ireland could be in for some major spout possibilities:

A general round up seems to confirm where any action takes place during the day:

If your in Ireland, then it's looking good. If you're in the SW (Cornwall, Devon, possibly South Wales) there may be some chances later in the day!

[Kain]

Don't know I don't have a house on a flood plain or near a river

Been a nice day today, all that constant flooding rain went to the west lol

Storms? maybe, they have to get something right

What an absolute (insert swear here)...Dude some people have lost everything and all you can do is mock? I hope it happens to you some day, they we can laugh at your misfortune.

It will be interesting if anything is about today, I don't see it msyelf...will probably all happen Sunday for cosford air show

[Methuselah]

Don't know I don't have a house on a flood plain or near a river

Not exactly what I'd call 'constructive'...