South East England & East Anglia Regional Discussion - June 18th 2012>

[Steve C]

Well you never know who your going to bump into that's for sure....

....for those who don't know the one on the right is Paul Sherman (the other one is related to me) who we met along with some other mad chasers at the top of Dunstable Downs last year - didn't see a storm though, sadly this one was a bust !

I suppose the skill must be in positioning yourself in the correct zone beforehand, having mobile radar and also a good knowledge of the road system.

Actually would be quite fun I guess, if you've the time.

My exhaust has blown driving home tonight. People might have thought the thunder had started a day or so early, until they saw the embarrassed driver...

[Steve C]

Quite exhausting reading the Convective Discussion thread! Lots of opinions.

Think I'll just wait and see what happens now.

[Keraunic]

Quite exhausting reading the Convective Discussion thread! Lots of opinions.

Think I'll just wait and see what happens now.

Me too. Although my weather apps don't look promising at ALL. And one is a Met Office one. *tut*. Seems like all the action will be further north according to met map. Oy vey.

[Steve C]

Me too. Although my weather apps don't look promising at ALL. And one is a Met Office one. *tut*. Seems like all the action will be further north according to met map. Oy vey.

I wouldn't be too despondent yet. I still think EA will get thunder tomorrow. Whereabouts though, who knows? Norwich could be favoured.

[Keraunic]

And Ipswich on Thursday maybe. Hope we all get a piece of the action anyway. Chin up each.

[Jason T]

Thunderstorms are amazing weather phenomenon. The first thing important you need to know is that you are more likely to get them, especially severe thunderstorms, when cold air is meeting up with warm air.

Usually this is caused by a cold front with much warm air behind it, and the warm air is in front of it ahead of a warm front. This is when the air is very unstable and a severe storm can occur. Warm humid air is lifted up and thunderstorms start to form. Solar heating can also cause air to be uplifted so you don't ALWAYS need a cold front to trigger severe storms

Once that humid air is lifted, it can then condense, and then clouds are formed. Usually you can tell a thunderstorm is forming by seeing big puffy Cuminolimbus which can get as high as 50,000 feet. The plains are great for seeing severe like supercells and these types of storms because it's flat for miles around with nothing obstructing your view. Usually they form an anvil shape which are some of the coolest sights to see.

The water in the atmosphere then changes from it's gas form to liquid form and the drops get bigger and bigger and some may even freeze because of the high altitude. At this stage, it is usually called the mature stage of the thunderstorm. This is an example

So to form a thunderstorm, you need:

• 
  - A lift mechanism like a cold front or winds coming off the ocean or mountain (usually from a strong weather system)
  - Daytime heating from the sun
  - And unstable air...usually humid air and weather
  

There are also three types of thunderstorms. They are:

• 
  - Orographic Thunderstorms (Caused by air lifted from a mountain or hillside)
  - Air Mass Thunderstorms (Caused by convection in a localized unstable air mass)
  - Frontal Thunderstorm (Caused by frontal weather boundaries which can cause supercells and squall lines)
  

**Severe Weather Note: What are squall lines?

Squall lines are long lived thunderstorms that form a line that can stretch for a couple hundred miles, usually from north to south

Edited June 26, 2012 by Jason T

[Steve C]

I'd split the air mass types into low base and high base storms too; high base storms being the type that usually coincide with the end of a heatwave and low base types being most of the others in SE England (eg winter storms, April showers etc.)

The memorable, long lasting ones, are more often the high base types - having said that my most memorable storm was one that broke over the High Woods area of Colchester, when I lived there, a couple of days before the total solar eclipse of 1999. I think this was a low base type and was accompanied by many flashes of lightning, with no discernable gap between them and the accompanying thunder, with seriously heavy rain that turned my road into a temporary river.

I've a video of this somewhere. I'll try and retrieve it, convert it into digital and post it here in the next month or so. No promises though, as the video could be useless now.

Edited June 26, 2012 by Speed67

[Keraunic]

@Jason. Thanks for that mate. A nice clear explanation of how a T Storm is formed. It'll be good to study this with charts so i can get a better idea of the mechanics of storm potential situations.

May I copy it for my storm blog?

[john pike]

http://www.weatherquestions.com/What_causes_thunderstorms.htm

try this one as well

i like the picture on there

[Steve C]

http://www.weatherqu...understorms.htm

try this one as well

i like the picture on there

That is a great picture of a supercell!

Obviously remembering that supercells are a relatively rare event in Britain. There was one in Oxford / MK area recently mind you, as MKsnowangel saw (I think)

Watching out for approaching anvil clouds is a great way to predict imminent showers too.

[Keraunic]

If a storm lasts all night or for several hours, is that a supercell or MCs? Or both?

[Jason T]

@Jason. Thanks for that mate. A nice clear explanation of how a T Storm is formed. It'll be good to study this with charts so i can get a better idea of the mechanics of storm potential situations.

May I copy it for my storm blog?

Yes no problem.Glad it helps.

[Steve C]

A typical storm cell may only last 45 minutes, but as they die, they can cause the development of new cells if in a large unstable region.

Supercells can individually last for hours, but typically will move on. Therefore if you have a night of thunder, it's likely to be the first scenario, which is a MCS.

Edited June 26, 2012 by Speed67

[john pike]

http://passporttoknowledge.com/storm/why/thunderstorms.htm

hope that helps

[Keraunic]

@speed 67 and John. Thank you both for those. I'm learning slowly but surely.

[Eskimo]

A disgusting 19.3C here at the moment

[Steve C]

A disgusting 19.3C here at the moment

Could be a difficult night for sleeping coming up.

[Keraunic]

Very sticky here as well. Seemed to turn muggy quite sudden. And it's very still and quiet.

[Steve C]

http://passporttokno...understorms.htm

hope that helps

That's a very good, jargon free, link.

[john pike]

add above 4 degress or more to the temperature chart above

this is for 12oclock so a little earlier

but i still think these look good for the south east

there will be more changes tomorrow

[john pike]

the fax chart is still a mess

however it has 564 air across the whole of the south east

that should help increase the temperature more and create

more instability

[Snowangel-MK]

Quite exhausting reading the Convective Discussion thread! Lots of opinions.

I thought your exhaust had blown earlier

There was one in Oxford / MK area recently mind you, as MKsnowangel saw (I think)

Yep, I did I chased that one over the Bucks/Beds county line

[john pike]

heres a video to explain the convection thread at present

[ZONE 51]

Northern storms 1 Southern storms 0

I think you're being a tad pessimistic. Parts of the the south are very likely to get thunder.

Was only joking! but it could be that northern areas get the lot...

But i agree i think we have a good chance of getting something thundery, and il be watching down south as much as the growing clouds in my own backyard!

[Bluebreezer54]

Good morning all. Despite this being one of my much needed rest days Im up early to check the prospects. Hopefully some of our more educated posters will be alomg shortly.

Currently 17.4c here with a dewpoint of 17.2c. The overnight minimum was 17.1c. Thats more like it !!