Uk Convective General Discussion & Forecasts - April 2012

[dave48]

This storm north of barking is really going well. Hoping it finds its way down here still in one piece.

Overall, a nice line moving into the south east now.

[bazookabob]

We heard a battering on our warehouse roof this lunchtime in Cleckheaton so we went out to find some pretty decent hailstones coming down (about half an inch diameter at times) so I shot a quick video on my phone- not sure how it will come out but hopefully you get an idea. The guy exclaiming about how it was F**king bright sunshine an hour ago is Bob, our warehouse grumpy old man.

Cheers

BB

[vortex_liam]

lewis ya needed to get into a more open area!

[IanR]

Seen a few massive anvils around today but they have all been way north and east of me and I'm stuck with this damn northwesterly wind, the sooner this northern air flow sets in the better!

agreed, the local forcast mentioned thunder in the showers, err no chance here with the wind from the Irish sea at this time of the year, just one or two moderate showers around just before lunch, you can see the Cb activity to the east however and the more stable small fuffly convective cloud toward the west

[Tim B]

There's a very dark area to my west though I'm not sure if that is the result of a big CB or shadows from the setting sun, however the radar does indicate heavy rain in that direction.

[Lauren]

hehe!! Has your name on it

Ha! Looks like it's going to miss me if that is moving in a SE direction.

[Stuart]

Look like a storm heading down to the Borders so i no longer there so missing out

[IanR]

There's a very dark area to my west though I'm not sure if that is the result of a big CB or shadows from the setting sun, however the radar does indicate heavy rain in that direction.

yes it seem to have come from nowwhere just gone dark to my northwest and we are getting heavy hail now, looks possibly thundery,

[robt]

Just watching a large storm bimble southwards to the west of me. I believe its the one thats dropping over Barnsley at the moment.

yes it seem to have come from nowwhere just gone dark to my northwest and we are getting heavy hail now, looks possibly thundery,

Theres a couple of interesting looking storms over the Preston area in the last 20 minutes.

[Weather Wizard]

It was shaping up to be a good day but somehow i managed to find myself in this tiny gap

[Supacell]

I didn't see anything out and about other than plain old rain. I swear I may have heard some thunder earlier whilst at work, sounded like it came from towards Leeds-Bradford airport and there was some heavy rain at that time, possibly the same one that dropped hail on Cleckheaton.

Maybe tomorrow???

[Suburban Streamer]

It was shaping up to be a good day but somehow i managed to find myself in this tiny gap

Yup me too! Surrounded but bone dry

[Costa Del Fal]

Tomorrow looks pretty similar to today however North of the Humber is unlikely to see anything Thundery. The Midlands, East Wales, East Anglia, CS & SE England are the regions at risk. Perhaps parts of Yorkshire may see something too.

[Tim B]

That Preston cell has just blown through but produced nothing more than moderate rain.

[Aaron]

I didn't see anything out and about other than plain old rain. I swear I may have heard some thunder earlier whilst at work, sounded like it came from towards Leeds-Bradford airport and there was some heavy rain at that time, possibly the same one that dropped hail on Cleckheaton.

Maybe tomorrow???

Today was looking like 'our' day but alas, nothing. Just had a 20 second light rain shower here, presumably from a decaying 'cell'. I guess we'll have to wait and see but as ever, I'm not going to expect anything.

It brings back memories of the dreaded storm season of last year. The set up is pretty similar really. Where's a hot southerly when you need one?

Edited April 11, 2012 by Aaron

[tara303]

It was shaping up to be a good day but somehow i managed to find myself in this tiny gap

LOL - me too. i'm 1 mile SE of heathrow, it got very dark, one 15min downpour now skies clearing to the NE.... poo!

[Convective]

Hi guys and gals again! Basically, I have just been looking at the long range forecasting charts and I don't know exactly what is takes but common sense is telling me that this is a Spanish Plume? I know that low pressure systems rotate anticlockwise and therefore when this low pressure arrive south of the UK, surely it should fire up milder air and if we were to have colder air from the north at the same time there would be some serious convection? Could be the first more severe event of 2012? If I have got the whole thing wrong, pardon me.. at the end of the day I am a 13 year old student and I know hardly anything

Edited April 11, 2012 by Convective

[Tim B]

This isn't a plume (I think) even though it might look similar there, these are being formed because of surface heating rather than an incoming warm airmass being forced upwards.

[Convective]

This isn't a plume (I think) even though it might look similar there, these are being formed because of surface heating rather than an incoming warm airmass being forced upwards.

I know this one isn't because the centre of the low pressure is drifting off slowly from eastern Scotland at the moment. What I mean is what about the charts in my last post? They are for 27th April roughly.. What do you think?

[multi cellular thunderstorm]

Not a lot happened in Nottingham today, just 1 hail shower, and I didn't hear any thunder or see lightning.

Still got to test out my new camera on some nice clouds...

Got to see some people got decent storms, I'm hoping for more here tomorrow.

Edited April 11, 2012 by multi cellular thunderstorm

[Supacell]

Tomorrow looks pretty similar to today however North of the Humber is unlikely to see anything Thundery. The Midlands, East Wales, East Anglia, CS & SE England are the regions at risk. Perhaps parts of Yorkshire may see something too.

I agree with this, although I think more eastern areas will have the best chance with a line from Lincolnshire down to the SE best, including Eastern Midlands and the Home Counties. I will be too far north for thunderstorms tomorrow, although a few heavy showers is possible. Of course, this could change by the morning but that is my take on current models.

[staplehurst]

Hi guys and gals again! Basically, I have just been looking at the long range forecasting charts and I don't know exactly what is takes but common sense is telling me that this is a Spanish Plume? I know that low pressure systems rotate anticlockwise and therefore when this low pressure arrive south of the UK, surely it should fire up milder air and if we were to have colder air from the north at the same time there would be some serious convection? Could be the first more severe event of 2012? If I have got the whole thing wrong, pardon me.. at the end of the day I am a 13 year old student and I know hardly anything

A true Spanish plume needs to have a layer of dry air above the hot surface air to act as a 'cap' to allow the loaded-gun scenario to occur (which in turn leads to the powerful thunderstorms associated with plume setups).

[Robbie Garrett]

For the spanish plume scenario to really kick off you need something similar to the following pictures. Low pressure to the west of the UK, dragging up hot air when it's get closer it's front hit the warm air and bang!! That's in theory what should have happened last June, 2500 kj/s of cape and a fairly decent -LI and a cold front to trigger.

A true Spanish plume needs to have a layer of dry air above the hot surface air to act as a 'cap' to allow the loaded-gun scenario to occur (which in turn leads to the powerful thunderstorms associated with plume setups).

Hi guys and gals again! Basically, I have just been looking at the long range forecasting charts and I don't know exactly what is takes but common sense is telling me that this is a Spanish Plume? I know that low pressure systems rotate anticlockwise and therefore when this low pressure arrive south of the UK, surely it should fire up milder air and if we were to have colder air from the north at the same time there would be some serious convection? Could be the first more severe event of 2012? If I have got the whole thing wrong, pardon me.. at the end of the day I am a 13 year old student and I know hardly anything

http://metofficenews...-spanish-plume/

Edited April 11, 2012 by Robbie Garrett

[Convective]

Ah I see. Thanks for that! Just out of interest, what is the highest CAPE you have seen before Robbie?

[Robbie Garrett]

Ah I see. Thanks for that! Just out of interest, what is the highest CAPE you have seen before Robbie?

Probably in the late 90s, I didn't see a chart for it... but we had Thunderstorms all night long, constant thunder and lightning every 2-3 seconds.

But recently, on the 28th June, there was about the same cape and negative lifted index you'd get in the tornado alley/states. (2000-3500) (LI -5 to - 7) But it's not all about the CAPE/LI - from what I learnt in my aviation training you need the following

1. Deep instability in the atmosphere such as that once the air keeps rising it will continue to rise, such as a steep lapse rate with warmer air in the lower levels and cold air in the upper levels.
   
2. A high moisture content - so high dewpoints
   
3. A trigger action, such as air rising from a front forcing the air aloft. A mountain forcing the air alof, or from strong heating of the air in contact with the airs surface, this is evident in the jungles in africa. Check out Sat 24, they get Thunderstorms daily. Or the heating of the lower layers of a polar air mass as it moves to lower latitudes (i.e towards the equator)
   

Various other things such as shear help provide thunderstorms.

Edited April 11, 2012 by Robbie Garrett