Storms and Convective discussion- 7th August onwards

[Guest]

Hmmm, not overly impressed with satellite imagery this morning, a large decaying mass of storms south of Brest looks like sending a mass of convective debris in south England this morning. 

[Marko1690]

Guys/girls, are these storms going to migrate over the Irish sea to northern Ireland from the mainland later today?

[davehsug]

BBC weather showing development further West  only really affecting Wales, Irish Sea and  N Ireland SW Scotland

[Guest]

Arome & Arpege are miles off with showers activity this morning and have significantly over estimated activity. At 7am Arome had pretty widespread convective activity over Wales and North East England when in fact there is almost none. 

[Petorious]

The new storm shield is now re named to UK.. (Not serious)

Edited August 10, 2020 by Petorious

[Ben Sainsbury]

New ConvectiveWeather forecast update includes removal of MDT area:

@staplehurst Any reasoning behind removal of the MDT area? Definite feels like there is less agreement among the models this morning from my own opinion.

Convective Weather

WWW.CONVECTIVEWEATHER.CO.UK

---

Forecasting thunderstorms and severe convective weather across the British Isles and Ireland for up to the next...

 

Edited August 10, 2020 by Ben Sainsbury

[Gordon Webb]

Day 1 Convective Outlook

VALID 06:00 UTC Mon 10 Aug 2020 - 05:59 UTC Tue 11 Aug 2020

ISSUED 06:25 UTC Mon 10 Aug 2020

ISSUED BY: Dan

Atlantic upper longwave trough will gradually sharpen on Monday, placing the British Isles under a broad southerly flow aloft. This will continue to advect a plume of high Theta-W slowly northwestwards through the forecast period, with a marked elevated mixed layer (EML) covering much of England and Wales and creating an environment with notably steep mid-level lapse rates.

 

... SUMMARY ...

Scattered thunderstorms are likely over parts of Wales / SW England / Irish Sea / SW Scotland during Monday daytime

Severe thunderstorms with large hail, flash flooding, strong gusts of wind and an isolated tornado will be possible over the Midlands and E Wales during Monday afternoon and evening

Scattered thunderstorms may affect parts of N / NW England, Irish Sea and southern Scotland on Monday evening and night

Isolated thunderstorms may be possible elsewhere, but with lower confidence

... WALES / NW ENGLAND / IRISH SEA / SW SCOTLAND - MONDAY DAYTIME ...

Elevated convection (bases around 8-10,000ft) is likely to be ongoing on Monday morning across parts of Wales, SW England and perhaps NW England, lifting gradually north through the day while expanding in coverage as a shortwave engages with a Theta-E ridge. Given the steep mid-level lapse rates and 500-700 J/kg CAPE, lightning is likely to be quite frequent in the most intense cells - especially over west Wales and parts of the Irish Sea where a greater coverage of lightning is expected. Lightning activity may weaken as storms approach the Isle of Man / eastern Northern Ireland / SW Scotland as profiles become increasingly saturated and instability weakens. Some hail may be possible, although the high cloud base and depth of hot air below suggests a lot of this will melt or shrink in size by the time it reaches the surface.

Elsewhere, isolated elevated showers/thunderstorms will be possible in a zone from Wales across the Midlands and SE England as a weak PV filament lifts north and engages the plume.

 

... MIDLANDS / E WALES - MONDAY AFTERNOON / EVENING ...

Strong surface heating is expected across southern and eastern England, with a slack low evolving in the vicinity of the M4 corridor. The EML will serve as a cap to surface-based development, and with T850s gradually warming through the day across SE England and East Anglia, these areas are likely to remain capped. However, some slight cooling at 850mb is possible over the West Country / SW Midlands, and IF surface temperatures can nudge close to the required trigger temperature of 30-32C (assuming dewpoints around 18-19C) this could breach the capping inversion and lead to explosive development in a loaded-gun environment, especially when aided by low-level convergence near the surface low centre and a PV lobe arriving from the English Channel.

 

Should deep convection occur, the backed low-level winds north of the surface low and modest flow aloft will create 20-30kts DLS which may be sufficient for organisation and perhaps supercellular mode. Given the substantial CAPE (1,000-1,500 J/kg) and steep mid-level lapse rates, very frequent lightning and large, damaging hail 2-4cm in diameter would be possible (although possibly shrinking somewhat in size as it falls through the hot surface air before reaching the ground). PWAT near 40mm and storm motion of ~20mph brings the risk of prolonged torrential downpours and flash flooding. Should storms exhibit supercellular characteristics, then they may deviate to the right of the mean flow and slow their forward speed. Given the large T-Td spread, cloud bases may initially be quite high, around 6,000ft - but due to a combination of storm processes, northward movement into less-hot air and nocturnal cooling of the boundary layer, cloud bases may steadily lower during the evening hours. Backed low-level winds will create 20-30kts LLS, which may bring the risk of an isolated tornado if cloud bases can lower substantially. Otherwise, inverted-V profiles suggests the risk of strong downburst winds 45-55mph. A SVR has been issued primarily for the threat of large hail and flash flooding, and to a lesser extent for strong winds and an isolated tornado.

 

The greatest risk of severe thunderstorms appears to be initially close to the M4 corridor and SE Wales, shifting northwards into the south / central / west Midlands and east Wales during the evening, and then NW England / Irish Sea later. However, as storms run north into an increasingly capped environment, they may become more elevated in nature. Much of this depends on how strong the cap is during Monday afternoon...

 

... NORTHERN ENGLAND / SOUTHERN SCOTLAND - MONDAY EVENING / NIGHT ...

As the shortwave ejecting north from France arrives during the evening hours, existing thunderstorms over the Midlands and/or new thunderstorms over NW England will likely grow upscale into a complex of primarily elevated thunderstorms over Cen N / NW England, while migrating northwards through the night towards southern Scotland. Lightning could be quite frequent in the strongest cells, and the threat of localised flooding exists from prolonged downpours. Some hail and gusty winds are also possible.

 

... ENGLISH CHANNEL - MONDAY NIGHT ...

A few other elevated showers/thunderstorms may be possible in parts of western mainland Scotland, and perhaps also exiting northern France and across the Channel Islands / English Channel towards S / SE England during the overnight period.

Convective Weather

CONVECTIVEWEATHER.CO.UK

---

Forecasting thunderstorms and severe convective weather across the British Isles and Ireland for up to the next 5 days.

 

I'll say this once for people who don't know but this type of weather scares me and so the forecast for midlands / east wales is not pleasant but for those that enjoy this then good luck to you all

edit - actually reading the detail it does not seem as straight forward as I thought and requires a few conditions to initiate temps of 30c to 32c which was not reached here yesterday , were short by 4c to 6c because of cloudy morning and it is current grey again

Edited August 10, 2020 by Gordon Webb

[bazookabob]

Nice view of the Ilkley shower 

[Guest]

TS just erupted in south Lyme Bay. 

[Marko1690]

40 minutes ago, davehsug said:

BBC weather showing development further West  only really affecting Wales, Irish Sea and  N Ireland SW Scotland

Il take it lol

[staplehurst]

20 minutes ago, Ben Sainsbury said:

New ConvectiveWeather forecast update includes removal of MDT area:

@staplehurst Any reasoning behind removal of the MDT area? Definite feels like there is less agreement among the models this morning from my own opinion.

Convective Weather

WWW.CONVECTIVEWEATHER.CO.UK

---

Forecasting thunderstorms and severe convective weather across the British Isles and Ireland for up to the next...

 

Yeah, I have concerns about the cap - latest models are perhaps 1C warmer at 850mb in the 'area of interest', and given just how finely-balanced the whole thing is it's all or nothing in that type of situation. Probably higher confidence of elevated storms breaking out over NW England and the Irish Sea later this evening than surface-based storms in the Midlands, but we'll see...

[Flash bang flash bang etc]

I’m working just inside the severe now

Will still probably chase a little north and west, but an easier day with less travelling thanks to the alterations to CW’s forecast

[Dreckly]

7 hours ago, ancientsolar said:

I wonder about those too, some really beefy downpours from those ! 

Very beefy! But only heard a couple of distant rumbles around 4am.

[dec10snow]

A summary of the various thunderstorm/connective forecasts for today and their links;

https://www.netweather.tv/weather-forecasts/uk/convective

https://www.estofex.org

http://convectiveweather.co.uk/forecast.php?date=2020-08-10

https://www.severe-weather.eu/outlooks-day1/weather-forecast-europe-aug10th2020-mk/

 

[AMeltedFlake]

Not too sure how I feel about today, being in East Wales, I'm within every single severe zone possible But waking up this morning, doesn't feel like a good start here Also, the overnight models seem to have pushed everything further north! Ugh

[chapmanslade]

58 minutes ago, Alderc said:

Hmmm, not overly impressed with satellite imagery this morning, a large decaying mass of storms south of Brest looks like sending a mass of convective debris in south England this morning. 

Currently about 400 miles south of you in the Charente and I can assure you it isn't 'crud' here. Storms have been initiating almost at random for the last 24 hours with very high cloud bases and we have a line of storms just passing through here now. I'll give them a good blow and send them your way.

The atmosphere here is juicy - we had a minimum of 22C last night which was the coolest for the last 5 days !

 

[TQWX]

26 minutes ago, Alderc said:

TS just erupted in south Lyme Bay. 

I thought I could here some thunder and there is activity but a bit far away, the sounds may have been something else. Getting closer though. This cam looks east into North Lyme Bay so something may pop up on there.

http://www.camsecure.co.uk/Camsecure3/broad.html

Edited August 10, 2020 by TQWX

[Calayte]

Slap bang in the middle of every ones severe forecast zones today. Could be a very interesting one, radar watching all day it is then!

[sparky1972]

bbc forecast is nothing to get overly excited about this morning, any chance of a storm pushed back till thursday, plenty of high cloud and an easterly breeze making it feel fresher, which feels pleasent

[TQWX]

Big rumble of thunder in Torquay!

[Harry]

Forecasts are utterly appalling for my area. Estofex doesn’t even place us in the 15% hatching. Booo!

[TQWX]

A few more strikes and more thunder now with large drops of rain. Strikes are moving north of me up towards Dawlish and Exmouth.

[Paul Sherman]

Love the Update from Dan clearly leaving out the Cod / ToD and POS 

Good Lad

[Eagle Eye]

5 minutes ago, Harry said:

Forecasts are utterly appalling for my area. Estofex doesn’t even place us in the 15% hatching. Booo!

We will get through this together

[ChannelThunder]

It's now a forth day running of AcCas-filled skies (they're starting very early today), again likely leading to nothing!

Thanks for the shout-out in a post last night @Paul Sherman RE Hants/Dorset area being the other COS down here