Convective / Storm Discussion Thread - 27th Feb onwards

[Windblade]

1 hour ago, Supacell said:

Everything pretty much going to plan at the moment with some light showers moving northwards from the channel into south-western England. These showers continue to push NW into Wales through the morning. So here goes my predictions.....
It is later on this afternoon onwards that I expect heavy showers and thunderstorms will break out. The thinking is that they will initiate along a line from the west of London to Bristol, maybe following the M4 corridor and also possibly somewhere close to and along the Welsh borders. Through the evening these develop and expand in coverage as they move slowly in a NW'ly direction. GFS has the strongest CAPE to the west and this is where I expect storms to be strongest. My red area shows where these storms are likely to be. This area of storms will be very hit and miss and to be fair most people will miss. However, where they do occur they could be briefly quite intense with locally high rainfall totals in a short space of time, gusty winds and small hail. There is a risk of localised flooding and this will be made worse by the fact it has been so dry and so rainwater could stand on the surface for longer. Wind shear is weak and so organised/severe storms are not likely.

Within the yellow box, there is still a risk of some thunderstorms although the risk is lower. Some models (NMM) break out the storms a little further north and so this would bring more of the Midlands and North Wales into the firing line. However, the risk here is lower than in the red box. Any storms that form during the afternoon/evening will continue to drift NW. Euro4 is still out on its own in thinking that very little will break out this afternoon, this worries me a little with regards me heading south to chase today.

Further thundery spells could then move up from the south later on today and into the first part of the night. The best chance of getting thunder from these tonight is further south, nearer the south coast. As they move northwards overnight and into tomorrow morning they look to lose most of their thundery activity.

For northern areas it looks likely to be tomorrow afternoon and evening where thunderstorms will occur. However, this will be reliant on residual cloud cover left from the overnight rain being able to clear early enough for temperatures to rise. Once the sun does break through across England and Wales it will not take long for temperatures to shoot up into the high teens/low twenties under a warm, humid airmass (today and tomorrow).

Thanks for the update Supacell. Still keeping my fingers crossed for north west kent this evening. 

[lassie23]

Not feeling humid at all yet, in fact it's cold this morning.

[Hodgheg]

Feels humid here in Sutton. Still a bit on the chilly side but the sort of feel you know once the sun comes out, it'll feel muggy. 

[Harry]

Seems as if the next 12-24 hours is going to be a classic case of now casting. Unstable plume of air which if the models are reliable will pop off in a broad swathe. Seems to me that a gnat's fart could trigger a cell anywhere across C/S England and Wales later today/overnight.

Kirkwood "humdinging thunderstorms" of usual concern lol. Very clear emphasis on "thunder" from the legendary Carol this morning though, h word aside. 

Beautifully clearing skies here in Tonbrige at the moment and temperature responding well - currently just shy of 16C.

First properly interesting day in ages, yay!!

[Harry]

21 minutes ago, lassie23 said:

Not feeling humid at all yet, in fact it's cold this morning.

NW LONDON DUMP HOLE - hahaha!!!!

[Windblade]

Unstable skies in tower hamlets this morning. Feeling a little more humid, but nothing noteworthy. Still, its early yet.

[lassie23]

38 minutes ago, Harry said:

NW LONDON DUMP HOLE - hahaha!!!!

You should  come visit sometime lol

[Dami]

totally gone cloudy here and got quite dull. you couldn't make it up.

[Windblade]

Showers beginning to break out over the southern coast. Still early but convection happening.

[Thunderstruck]

Some high level Mackerel clouds apperearing here now, and also what may be a tower or two far off in the West towards London, but it's very hazy so hard to tell for sure.

[dragon falls]

Quite chilly here sun first thing 

[SenlacJack]

1 hour ago, Harry said:

NW LONDON DUMP HOLE - hahaha!!!!

He's not wrong, I used to live just up the road from him, best thing I ever did was moving down here to Sussex by the sea 2 years ago !

After a couple of hours of warm sunshine here the cloud sheet is moving back in, feeling quite humid and 18.5c.

[Dangerous55019]

Morning all, in the past hour the heat has really started to build up here in North East Wales... I'm outside, so not sure of the current temp, but it certainly feels a lot more humid.  

We've currently got clear blue skies, but with a very hazy appearance to them... Just like we normally get when something is brewing  

Good look to everyone who's hoping to get something from this current storm threat 

[Windblade]

25 minutes ago, Jcweather said:

Some high level Mackerel clouds apperearing here now, and also what may be a tower or two far off in the West towards London, but it's very hazy so hard to tell for sure.

Can't see any towers here in Tower Hamlets (no pun intended). Sky is quite milky but clearning slowly and some nice AC is building up to the south. 

Curious - what are Mackerel clouds? I've never heard that cloud name before.

Edited May 11, 2017 by Windblade

[Harry]

Just now, Windblade said:

Can't see any towers here in Tower Hamlets (no pun intended). Sky is quite milky but clearning slowly and some nice AC is building up to the south.

Agreed, signs of Ac development here in Tonbridge too. 

[Windblade]

12 minutes ago, Windblade said:

Curious - what are Mackerel clouds? I've never heard that cloud name before.

Don't worry, I googled it. I just thought they were AC but the "mackerel" description is to do with the way the pattern is arranged. Answered my own question!

 

[Flash bang flash bang etc]

Looking on sat I'd say based on where there is currently clear skies anywhere from Maidenhead and westwards looks in for some decent storm chances later on. Reckon the Hants, wilts and off west from there is also good.

theres a nice clear break moving up right now to clear the cloud over surrey and London but with only a few hours of decent sun I'd say it's more likely these areas will see heavy rain mostly but it's all still to play for.

I'm in London at the moment but hoping for an early finish so I can take the storm-mobile up the M4 to Reading and find somewhere there to hang out for the best possible chance.

Lucky for us southerners we might get some weak imports later - it's always good to have a back-up option when chasing in the UK 

[Azazel]

My thoughts for any action should it occur today. Quite a broad swathe inside the yellow box. Red box is where I would expect any significant convection to occur later today.

[Dimahop]

Hi guys, newbie here. I'm a keen storm photographer based in South croydon but working just outside Crawley. Nice to see these updates. It's clouding up pretty well here but difficult to see any tower growth as a lot of Low cloud. Was going to head south towards coast later myself but I'll follow development on Blitzortung

[Flash bang flash bang etc]

Bang! Active cell ignition near Cherbourg!

heading toward Bristol I think but dunno how far it'll get

[Mapantz]

Not often you have a pressure reading of 994hPa and have blues skies and warm temperatures.

[MP-R]

7 minutes ago, Flash bang flash bang etc said:

Bang! Active cell ignition near Cherbourg!

heading toward Bristol I think but dunno how far it'll get

Yes please! 

[Windblade]

7 minutes ago, Flash bang flash bang etc said:

Bang! Active cell ignition near Cherbourg!

heading toward Bristol I think but dunno how far it'll get

Awesome. 

[SteveB]

Suns out now & temp shot up 4c in less than an hour.

Humidity 61%, dewpoint 10.0c

Edited May 11, 2017 by SteveB

[West Sussex Kate]

Really warm in Sussex today!