Convective Storm/Discussion thread - 16/07/16 onwards

[Flash bang flash bang etc]

Anyway looks like cells kicking off further borth than anticipated at present. We need something to trigger south of the IOW ideally

[Nick F]

Slight update to my storm forecast issued last night, to include a SLIGHT risk of severe weather from central S England NE to E England, can't ignore large SBCAPE values showing and potential for low-level inversion to be breached where CZ develops inland here. It is small/isolated risk, but should sfc based storms develop, they could quickly turn severe:

Storm & Convective Forecast

Issued 2016-08-26 23:02:33

Valid: 27/08/16 06z to 28/08/16 06z

CONVECTIVE/STORM FORECAST - SAT 27TH-AUG-2016

Synopsis

Upper trough to the west of the British Isles will slowly advance eastwards during Saturday. Ahead of the trough, a plume of warm and moist air, characterised by WBPT/Theta-w values reaching 16-18C, advects north in across S England early Saturday. A warm front will move in across S England by 12z Saturday marking the boundary of warm and humid air moving in from the south at the surface.

… E WALES, S ENGLAND, MIDLANDS, E ANGLIA, N ENGLAND …

An elevated mixed layer (EML) characterised by steep mid-level lapse rates will move north in tandem with plume of warm/moist air below. Isentropic lift of the plume ahead of the warm front may create sufficient instability in the mid-levels above a stable cooler and drier boundary layer to support development of scattered heavy showers and perhaps isolated elevated thunderstorms early on in the day across southern counties of England. These early showers and isolated storms tending to drift NE across The Midlands and Eastern parts of England during the day north of the warm front above a stable cool/dry boundary layer. Any elevated storms could produce frequent cloud-to-ground lightning locally and also a risk of flash-flooding. So have issued a marginal risk for severe weather.

Drier and sunnier conditions returning to S/SE England late AM into PM, where surface will likely remain capped, but with strong surface heating of humid airmass, where skies clear, yielding towards 1000 j/kg CAPE. There is a small risk that surface breeze convergence and surface heating will be sufficient to overcome the cap to produce some isolated thunderstorms here later afternoon/early evening. Any sfc-based storm that does develop may  organise, given 30-40 knts of DL shear, to produce large hail (2-3cm), strong winds gusts and torrential rain leading to flash-flooding. Large CAPE modelled, enhanced LL shear near/along warm front and low LCLs look favourable for storm rotation that may lead to a tornado too. Have higlighted a SLIGHT risk for this potential for severe weather near the warm front from central S England NE across S Mids, Nern Home Counties, Lincs and E Anglia. BUT it should be stressed that surface-based storm development is rather uncertain given cap, cloud clearance and forcing (or lack of).

Further N and W, increasing large scale ascent by upper trough approaching from the west, lift from shortwave trough moving in across the SW early evening and increasingly cyclonic and strengthening mid-level flow may trigger some surface-based storms along the edge of unstable plume across E Wales, Midlands and parts of N England during the evening. These storms could produce large hail, gusty winds and a risk of flash-flooding, but given uncertainties over extent, will stick with the MGNL risk for here for now

Issued by: Nick Finnis

[Bolt from the Blue]

I'm taking today's potential with a pinch of salt 

[Flash bang flash bang etc]

5 minutes ago, AIRMET said:

I'm taking today's potential with a pinch of salt 

Can I have a bit too...

 

looks ke like U might be too Far East but it's all to play for!

[Frosty hollows]

Well, I'm on that (possible) CZ here, and all we've got is intense drizzle which I've possibly brought home from Cornwall. However, I've also brought back three washloads, 2 of which are on the line atm. There is normally a direct correlation between the amount of washing I've done and the amount of rainfall we get. Add to this the fact I'm about to do an outdoor bootcamp and I can guarantee hail, torrential rain, thunder, lightnining and possibly a tornado

[Gordon Webb]

Even at this stage there is a great deal of uncertainty and I were a betting man I would bet on not as much happening as this the UK and not much happening seems to be the normal and also reading all the forecasts there seem to be plenty of factors that could scupper this altogether 

Edited August 27, 2016 by Gordon Webb

[Flash bang flash bang etc]

The sky here says storms are on their way, can the sky lie? Well it has in the past . Luckily I have lots of work to do while I sit and wait so if all else fails I'll have achieved something this morning!

[TEITS]

Already just had a heavy shower. The area of activity you see on the radar is pretty much the area the Euro4 has consistently predicted for the past couple of days.

So what is likely to happen today is this area will intensify during today whilst drifting north into Lincs/Humber before finally clearing into the N Sea. I do not see anything for the far S or SE, not even a light shower.

[wimblettben]

Skies certainly look unstable and thundery looking here this morning though whether it brings any actual thunder is open to doubt.

Having just seen Sky News weather everything looks to be too far north of here to be honest with most storms shown to be over the midlands.

[Cableguy]

10 minutes ago, TEITS said:

Already just had a heavy shower. The area of activity you see on the radar is pretty much the area the Euro4 has consistently predicted for the past couple of days.

So what is likely to happen today is this area will intensify during today whilst drifting north into Lincs/Humber before finally clearing into the N Sea. I do not see anything for the far S or SE, not even a light shower.

Already had a couple of showers here, I would class us as SE

[Flash bang flash bang etc]

Here we go!!! Major initiation in the channel!

[Evening thunder]

Thunderstorm just formed just west of Guernsey, interesting if that could be earlier initiation of an elevated storm cluster than anticipated.

Looks to be heading towards Dorset ish

[Flash bang flash bang etc]

That couldn't be in a better place for our area... :-D

[Harry]

20 minutes ago, TEITS said:

Already just had a heavy shower. The area of activity you see on the radar is pretty much the area the Euro4 has consistently predicted for the past couple of days.

So what is likely to happen today is this area will intensify during today whilst drifting north into Lincs/Humber before finally clearing into the N Sea. I do not see anything for the far S or SE, not even a light shower.

Inclined to agree with TEITS, my neck of the woods in the far SE has continually shown to miss any storm action today. Although I've never held the Euro4 as a bastion of accurate predictions. Nor was I impressed when the only place that saw a proper storm the night before last was Kent (not favoured by the models then either).

Its sunny here, humidity is up and temperatures already in the low 20s, could easily see 29C - 30C today...NMM modelling some pretty high MUCAPE here too (well over 1000 - 1500 with LIs -6 to 8).

One thing is certain, it could be an interesting and unpredictable 24 hrs

Edited August 27, 2016 by Harry

[Flash bang flash bang etc]

It had a flourish but then it seemed to stop. Whoa a Lamborghini just went past to quick it made my van rock!

[Gonzolio Martinez]

Accas here in Norwich, hopefully a sign of good things to come

[TropicThunder]

Well that nice little storm by Guernsey is encouraging, also one just sparked up near Paris, hopefully a sign of things to come. However we're currently sat under a blanket of grey murk, and it also feels a bit fresher than it has done of late. Hoping for an interesting day.

[Harry]

Beeb forecast of where the storms will occur is interesting, bit further south and east than I was expecting 

[Eye to the sky]

Growing considerably darker here.Looking at the radar the first heavy showers are just to the south.Could be in a good location here for today's action.

[Flash bang flash bang etc]

21° here now near Staines. Looks like things are sparking up across the channel - also the sun keeps popping in and out so the cloud cover isn't causing too many problems...

[Chris K]

Going to be too far West here I think. Good luck all certainly looks promising with showers beginning to develop already.

[Shane Wheeldon]

Well i am going to put my washing on the line, that is how confident that my area will not see any storms today, that chunk on the radar is passing to the East of here. Dont expect anything here this afternoon either, too far west! 

[Ben Sainsbury]

To the west of the storms in the channel, looks to be plenty of clear sky on Sat24 so some good surface heating early afternoon!

[Frosty hollows]

Ely is electric!

[alexisj9]

1 hour ago, TEITS said:

Already just had a heavy shower. The area of activity you see on the radar is pretty much the area the Euro4 has consistently predicted for the past couple of days.

So what is likely to happen today is this area will intensify during today whilst drifting north into Lincs/Humber before finally clearing into the N Sea. I do not see anything for the far S or SE, not even a light shower.

Going by my sky I'd say you are right about here, clear blue, no instability in the sky at all.