Convective / Storm Discussion Thread - 31st May 2017 onwards

[Greeny]

Since just before midday when I heard the first decent boom of thunder out of nowhere, its been thundering sporadically, last thunder was fairly distant about 15 minutes ago and before that the last lightning that was detected on lightning maps was 30 minutes before that. Frequency has been slowly dropping. I haven't seen any lightning today myself, the leading edge did have some high level mammatus. Judging by reports the nearest overhead lightning to me in Norwich was East Dereham way.

Edited June 27, 2017 by Greeny

[chrisbell-nottheweatherman]

Just now, Greeny said:

Since just before midday, its been thundering sporadically, last thunder was fairly distant about 15 minutes ago and before that the last lightning that was detected on lightning maps was 30 minutes before that. Frequency has been slowly dropping. I haven't seen any lightning today myself, the leading edge did have some high level mammatus. Judging by reports the nearest overhead lightning to me in Norwich was East Dereham way.

I'm south of you and saw a bright flas to the north-west around 12:30.

[Flash bang flash bang etc]

temperature has risen from 18° about 30 mins ago to 23°

[Chloe]

Is anyone getting storms in West London as planes are flying overhead really low! ???

[Greeny]

Finally got a decent flash of purple lightning, it just all of a sudden sprung back into life.

[Methuselah]

7 minutes ago, Chloe said:

Is anyone getting storms in West London as planes are flying overhead really low! ???

Eh? Are you suggesting that low-flying jets make loud thunder-like noises...As well as produce fake temperature records, Chloe?

I always put the loud noises down to the bin-men!

[LightningLover]

Things are re-developing over France. Wether it will reach us or not is a different matter.

[Allezwasps.]

Lots going on over in france it seems 

[Flash bang flash bang etc]

I think things are looking good as western areas of France have switched the mains back on :-)

But what I do not fully understand is how it can be raining for several hours and then allow convective weather to push in behind it without requiring at least a brief spell of sun to re-energise things.

Can anyone explain this?

[chrisbell-nottheweatherman]

5 minutes ago, Flash bang flash bang etc said:

I think things are looking good as western areas of France have switched the mains back on :-)

But what I do not fully understand is how it can be raining for several hours and then allow convective weather to push in behind it without requiring at least a brief spell of sun to re-energise things.

Can anyone explain this?

Does this (from today's Netweather storm forecast) help?

Quote

This heavy rainfall and possible elevated convection develops on the NW edge of high WBPT (Wet bulb potential temp) plume across mainland Europe, probably due to engagement of cooling aloft as upper trough approaches from the west and also isentropic uplift of the warm/moist conveyor above cooler/drier NEly surface flow over SE UK. Possible isolated embedded elevated t-storms spreading N across the Channel across SE UK within area of heavy rainfall developing and spreading N may pose a risk of localised flooding, given PWAT (Precipitable Water) values of 33-36mm. This heavy rain and embedded storms continuing overnight into Wednesday morning, with a continued risk of localised flooding. Have issued a MARGINAL risk for risk of flooding.

 

[tomp456]

6 minutes ago, Flash bang flash bang etc said:

I think things are looking good as western areas of France have switched the mains back on :-)

But what I do not fully understand is how it can be raining for several hours and then allow convective weather to push in behind it without requiring at least a brief spell of sun to re-energise things.

Can anyone explain this?

Because the storms are higher up in the atmosphere and do not rely on surface heating from the sun for food 

[Flash bang flash bang etc]

1 minute ago, tomp456 said:

Because the storms are higher up in the atmosphere and do not rely on surface heating from the sun for food 

Lol, food

So they get their energy from the moist upper layer(s) of air then?

Would be interesting to watch from a plane or balloon (from a safe distance hehe)

[chrisbell-nottheweatherman]

14 minutes ago, Flash bang flash bang etc said:

Lol, food

So they get their energy from the moist upper layer(s) of air then?

Would be interesting to watch from a plane or balloon (from a safe distance hehe)

Essentially, the energy is coming from a collision of a cool, dry Atlantic airmass and a warm, moist airmass from a plume.  Normally, when a plume destabilises over the UK, the warm, moist air is established in situ and is present from the ground up, hence heating from the ground is a factor in destabilising the atmosphere.  As the plume is currently trying to move in at a time when the temperture near the surface is fairly cool, it's moving in above it, generating a temperature inversion (warmer air above cooler air), so daytime heating of the ground isn't a factor.  What's destabilising that already elevvated warm air, however, is the cool, dry air from the north west which is wedging under the warm air and lifting it, hence the base of the storms are much higher than usual and daytime heating from the sun is irrelevant.

Edited June 27, 2017 by chrisbell-nottheweatherman

[tomp456]

When's this elevated stuff supposed to arrive?

its got brighter over the last 30 mins on the south coast

[chrisbell-nottheweatherman]

2 minutes ago, tomp456 said:

When's this elevated stuff supposed to arrive?

its got brighter over the last 30 mins on the south coast

I think there's some on the way from France, but some of East Anglia has already had elevated storms. 

[Flash bang flash bang etc]

Would the south coast (say Bognor / Selsea area) be a good place to park up and wait for storms?

Another option is Butser Hill, but worried that might be a little too far west on this occasion.

Current thinking is to start heading north and keep ahead of it but that's dependent on how heavy the rain is around the approaching storm front

[NO LONGER POSTING]

Almost "steamy" here it's very tropical almost with some heavy rain

[Ciderwithrosie]

spots of rain falling in the good  ol south west . Nothing extravagant by any means, and not bothered abt thunder , but I think the rain may be an issue as a local weather service has just popped up with a warning . 

Glad those who like storms are getting them . 

[matt111]

Probably way too far west here but it's certainly noticeable how humid it is, which is making it feel warm despite it only being 16°C. 

[Ciderwithrosie]

I'm even more to the west of you and it's humid here . Been an odd sort of a day . Not fun with pneumonia! 

Bigger spots now .falling faster . 

[tomp456]

31 minutes ago, chrisbell-nottheweatherman said:

I think there's some on the way from France, but some of East Anglia has already had elevated storms. 

Ahhh.

we had a few rumbles earlier, hope the main course is still it come

[DAVID SNOW]

26 minutes ago, chrisbell-nottheweatherman said:

I think there's some on the way from France, but some of East Anglia has already had elevated storms. 

All that stuff in France wont even clip Kent(imo).

[TJS1998Tom]

1 minute ago, DAVID SNOW said:

All that stuff in France wont even clip Kent(imo).

It'll probably ease off as it reaches the coast

[Allezwasps.]

The belgian storm magnet is in operation again ......

[Dami]

not really humid not really raining much, missed out on thunder.