Storm/Convective Discussion

[Cloudwatcher]

I'm not happy, in fact I'm quite sad, What is it with this area. Big storms reported the night before last in N Wales Connahs Quay area ten miles away, and absolutely nothing here...again. And today is a repeat of all of this week, no sun just a blanket of featureless grey cloud and and not enough heating to kick anything off. Arrrgh. Someone please give me some hope today...(skulks off to be miserable in The No-Storms Club...)

I am living in the dullest part of the UK weatherwise!

[Coast]

Temps and DP's keep rising (and proportionally quicker and higher than yesterday I believe) something's got to blow the safety valve surely?

[Harry]

Any specific reason why many of the MetO weather stations, including Heathrow, are unavailable?

I know this is not exactly convective discussion, but could be interesting if they use the data from their stations to issue/update warnings etc!

Temps and DP's keep rising (and proportionally quicker and higher than yesterday I believe) something's got to blow the safety valve surely?

I take it that makes it look that bit more promising for us in the barren lands then Coast

You may be ok though Coast - some big storms possible across the Channel throughout this evening which could provide you with a pleasant light show at least

Edited July 2, 2009 by Harry

[dallas]

Any specific reason why many of the MetO weather stations, including Heathrow, are unavailable?

I know this is not exactly convective discussion, but could be interesting if they use the data from their stations to issue/update warnings etc!

I take it that makes it look that bit more promising for us in the barren lands then Coast

You may be ok though Coast - some big storms possible across the Channel throughout this evening which could provide you with a pleasant light show at least

Was like that N/W Kent last saturday, temps and dew points slowly rising then bang by late afternoon

[Joneseye]

On the positive side, at this time today (compared to yesterday) there is much higher numbers/volumes of PPN and LG Strikes.

Glad someone is being positive, this thread is getting worse than the will it snow threads do in winter...

The one difference from the previous days this week is that pressure is dropping and there is a trigger there for storms. I for one am more optimistic today and tomorrow of seeing something... still all about timing though

[Bofh]

blimey lads have you seen that lot rolling in to the south of france !

if only

[dallas]

blimey lads have you seen that lot rolling in to the south of france !

if only

Yeah nice size chunk heading east, they always seems to get good concection there

[TEITS]

Have to say I can see many disappointed people today.

As the front which is currently bringing the heavy rain in the SW moves E overnight this will weaken into nothing more than patchy rain. However the front will re-ignite tomorrow for some very lucky locations.

Look at this fax chart for tomorrow.

http://cirrus.netweather.tv/fax/PPVG89.png

The temps ahead of this front will be around 27C for E Anglia/SE/E Midlands, possibly higher if the front is moving slower than predicted. Now for locations such as E Anglia/E midlands/Lincs/NE England this will set off some impressive storms late tomorrow morning into the afternoon.

So in summary if todays front moves across your region during late evening/overnight then the risk of storms is very small.

[Cheese Rice]

Temps a good degree higher at this time than yesterday, hopefully will set of something.....

[Harry]

Have to say I can see many disappointed people today.

As the front which is currently bringing the heavy rain in the SW moves E overnight this will weaken into nothing more than patchy rain. However the front will re-ignite tomorrow for some very lucky locations.

Look at this fax chart for tomorrow.

http://cirrus.netweather.tv/fax/PPVG89.png

The temps ahead of this front will be around 27C for E Anglia/SE/E Midlands, possibly higher if the front is moving slower than predicted. Now for locations such as E Anglia/E midlands/Lincs/NE England this will set off some impressive storms late tomorrow morning into the afternoon.

So in summary if todays front moves across your region during late evening/overnight then the risk of storms is very small.

Indeed, although isn't it the trough leading ahead which may also spark storms before the arrival of the cold front?

Edited July 2, 2009 by Harry

[sammie]

Probably because you're under a warm humid air mass and have high SB CAPE so with surface heating thundery showers/storms will break out quite widely in Scotland.

Thats the thing thats bothering me, we've been sat under this warm and humid air mass for almost a week and we haven't seen a single peak of sunshine or rain. Just very think grey cloud. With this cloud cover and no real surface heating there's no trigger for these thunderstorms. I know I'm being pessimistic but I just can’t see this kicking off.

Only time will tell, for the west of Scotland its gonna be hit or miss, something will kick off if the damn cloud breaks and lets the sun though but other than that. Something needs to get rid of this stagnant air its driving me crazy.

And just really quicky, what exactly is SB CAPE, I know what CAPE is but what does the SB mean? There we go dumb question of the week over with haha.

Edited July 2, 2009 by sammie

[anvilhead]

looking at the charts I dont think its certain that it'll be a damp squib tonight for more south/western areas - if anything forms over france, from what I can see the atmposphere would keep them going and import to southern areas, with good life and jet moving north .. we'll see though -

[Lewis]

Surface Based CAPE (Convective Available Potential Energy) is SBCAPE.

Also please remember CAPE does not take into account a cap, you have sh*t loads of CAPE, but if you dont have a trigger its useless.

Edited July 2, 2009 by Lewis

[kaz]

love this sat pic it almost looks like its getting a kick up the bum to move more easterly

http://www.sat24.com/

[Harry]

looking at the charts I dont think its certain that it'll be a damp squib tonight for more south/western areas - if anything forms over france, from what I can see the atmposphere would keep them going and import to southern areas, with good life and jet moving north .. we'll see though -

It's that E'rly breeze which has been the pain in the backside so far this year! If it were a southerly, game on...though I think the E'rly running through the channel could well prevent French imports getting to us!

love this sat pic it almost looks like its getting a kick up the bum to move more easterly

http://www.sat24.com/

Indeed - you can also see the first signs of instability spreading to C and N France ahead of the front.

Edited July 2, 2009 by Harry

[TEITS]

Indeed, although isn't it the trough leading ahead which may also spark storms before the arrival of the cold front?

Yes I should of mentioned that.

Under such conditions you do see storms forming ahead of the cold front aswell as along it hence the trough. There is the chance of storms forming for Wales/SW England/W Midlands but at the moment I remain unconvinced.

In these situations its always a case of timing i.e front coinciding with heating of the day. So if this front moves across your region during the overnight period then the risk diminishes. This is why the timing is perfect for the locations I mentioned in my previous post and if I had to say which location is in prime spot then I would say inland Norfolk tomorrow late morning/afternoon.

Most probably wrong though.

[sammie]

There is SB (Surface Based) and ML (Mixed Level) CAPE. Surface based CAPE is reliant on the sun or some other form of trigger or forcing mechanism whereas Mixed Level CAPE is instability in the mid levels of the atmosphere due to cool dry air aloft.

Thanks for the explanation!

Surface Based CAPE (Convective Available Potential Energy) is SBCAPE.

Also please remember CAPE does not take into account a cap, you have sh*t loads of CAPE, but if you dont have a trigger its useless.

Thats the problem here, I think all the things are in place, just with this thick cloud in the way theres no surface heating to release the SBCAPE. It's so fustrating

[Coast]

You may be ok though Coast - some big storms possible across the Channel throughout this evening which could provide you with a pleasant light show at least

I'll go with an overnight lightshow but no rain for tomorrow in the day please, I don't want a Glastonbury type mud bath at Goodwood!

Edited July 2, 2009 by Coast

[StormChaseUK]

Here the front was overhead earlier, but has now moved back west.

[Wilxy]

Some convection starting to happen in N Scotland.

[Coast]

Hmmmmmm, the first time in over a week there are clouds forming over Sussex and I believe they are Cu's......

[Cheese Rice]

Friday seems to be the best chance of storms for these parts, hopefully some heavy downpours on Friday afternoon, anybody got any ideas on what the chances are for anything decent round these parts??

Meto "Rather cloudy with outbreaks of rain which will become heavy at times with the risk of some thundery downpours later. Maximum temperature 24 °C."

[Paul Sherman]

Torro Have just released a Convective Watch which might interest some of you guys further North and West

Cant seem to find the link - Maybe someone else can ??

[StormChaseUK]

Paul Demari, hereford & worcester - going for hot day with strong sunshine, winds from east, south east. 27c to max out at 32C this afternoon

overnight cool fresher weather and thunderstorms overnight , fresher tommorow morning. didnt seem that confident on widespread storms.

[Lewis]

A TORRO CONVECTIVE DISCUSSION has been issued at 11:15GMT on Thursday 2nd July 2009

Valid from/until: 11:15-21:00GMT on Thursday 2nd July 2009 for the following regions

Parts of (see map)

SW England

Midlands

NW England

Scotland

Wales

Eire

N Ireland

THREATS

Marginally severe hail; isolated tornadoes; gusty winds; heavy rain; CG lightning.

DISCUSSION

Three potential areas of convective development seem possible today: West of the cold front, across Eire and western parts of N Ireland; along the cold front, through SW England, Wales, and western Scotland; in the moist plume ahead of the cold front, from the Midlands through parts of NW England into central Scotland.

West of the cold front, several hundred J/Kg of CAPE are forecast to develop across western Eire/W N Ireland, with reasonable shear. Loosely organised clusters may develop with a marginal severe hail/wind threat.

Along the cold front axis, elevated and perhaps embedded surface based showers/storms are possible, although the overall coverage of thunderstorms may be fairly low. Any storm which develops will do so in an environment favourable for gusty winds/marginal hail, as well as producing heavy rainfall.

Ahead of the cold front, there are indications that isolated storms may form across parts of the Midlands and then move NNW into NW England. Shear may be sufficient for a small loosely organised cluster capable of producing marginally severe hail, along with frequent CG lightning.

In the same airmass across Scotland, there is likely to be somewhat stronger shear, perhaps enough for weak mesocyclone development. This would enhance the wind/hail threat, and given an increasing low-level flow, a tornado is possible too.

Lack of stronger shear precludes a WATCH

Overnight tonight, there is a risk of thunderstorms spreading into southern counties of England, along with increasing deep-layer flow. These could bring the risk of marginally severe hail and winds.

Forecaster: RPK.

UK MAP

Edited July 2, 2009 by Lewis