Storms and convective discussion - 18th June 2020 onwards

[Guest]

A poor night given the forecast, think I’ll go upset myself now and have a read in the model output thread and see how many weeks of miserable autumn like payback weather we have to put up with now! 

[Dorsetbred]

31 minutes ago, Paul Sherman said:

Big Old Storm just out to my east over Herne Bay way running up the coast but still getting the thunder from it 

Well that's cracked the duck of the last 11months then..

[Blazerblue]

Ooh heading this way, will it reach the triangle?!

[Paul Sherman]

Now if the Cone and Triangle fell on the same day that would be something

[Tom Jarvis]

Cannot get the vids on here but you can find them on my Twitter @sandle08

[fujita5]

Just had a few rumbles over Clacton, mainly from IC strikes, only one CG observed which was before landfall. Storm rapidly dying out now.

[Vickie White]

Morning all.

Had some heavy rain and a few distant rumbles of thunder between 6am and 7am, did'nt see any lightning, but at least we had something.

[sparky1972]

Morning all, well after a quiet night its a very cloudy morning which will keep things storm free i would imagine.

[Gordon Webb]

Day 1 Convective Outlook

VALID 06:00 UTC Fri 26 Jun 2020 - 05:59 UTC Sat 27 Jun 2020

ISSUED 06:36 UTC Fri 26 Jun 2020

ISSUED BY: Dan

Longwave trough will become increasingly negatively-tilted as it continues to approach Britain and Ireland on Friday from the southwest. A plume of high Theta-E will continue to nudge gradually northwards and eastwards across Britain through the day, providing the focus for several waves of potential thunderstorm activity as shortwaves lift northwards in the south/southeasterly flow aloft on the forward side of the upper trough.

At 06z Friday, scattered clusters of elevated showers/thunderstorms may be ongoing almost anywhere in a NW-SE line from the Hebrides / W Scotland through the Irish Sea into Wales / Midlands / SE England - however, there will likely be many areas not experiencing thunderstorms at this time. This line (active or inactive) will continue to lift northeastwards through the day, and so the areas at risk of semi-random outbreaks of elevated shower/thunderstorm activity will also shift northeast accordingly, broadly clearing to the North Sea by early afternoon, but pivoting such that the instability plume lingers across central and southern Scotland. 

 

In its wake, substantial capping will likely persist across much of southern Britain, generally restricting any surface-based convection from developing - not least due to slightly reduced surface temperatures following morning mid-level cloud. Forecast profiles suggest temperatures of at least 34C would be required to break the cap in SE England, which seems unlikely. Further north, surface troughing is expected to develop, perhaps even a heat low, with low-level confluence and convergence combining with some orographic forcing to bring a greater risk of surface-based thunderstorms developing. A wind shift line, associated with the surface trough axis, may also lift northeast across England during the day, which may also provide the focus for initiation.

 

The area at greatest risk of surface-based development is considered far NE Wales through north Midlands into northern  and eastern England. Here, the thermodynamic and kinematic environment would be supportive for organised and potentially severe thunderstorm activity, and while winds will be fairly unidirectional through the cloud-bearing layer, shear may be adequate for splitting supercells - especially during the evening hours over NW / N England. Given the magnitude of CAPE (1,000-2,000 J/kg) and very steep mid-level lapse rates, lightning could be very frequent with large to very large hail (3-5cm in diameter, and perhaps very locally larger) possible from the most organised cells. A tentative MDT has been introduced where showers/thunderstorms may be more numerous. A SVR has been introduced primarily for the threat of damaging hail. There is a level of uncertainty as to how widespread thunderstorms may become during the afternoon and evening hours, primarily due to the presence of the cap, especially towards the south. Overall the best environment - weaker cap and stronger shear overlapping with substantial CAPE - will be over northern England and perhaps into southern Scotland.

A PV filament arriving from the southwest during the evening hours may also encourage upscale growth, especially across northern and eastern England with thunderstorms potentially becoming more numerous with time (primarily elevated), these then likely to swing into eastern Scotland during the early hours of Saturday. Other elevated thunderstorms could develop along the same line farther south across East Anglia and perhaps parts of SE England, with others advecting from France also - and so an uptick in activity is possible over these areas during the late evening and night hours, but confidence is not particularly high.

 

Additional scattered thunderstorms are also likely across parts of Scotland and northern portions of Ireland, with marginally-severe hail (generally up to 2cm in diameter) possible and shower training bringing the risk of localised flooding. A low-end MDT has been introduced where there is reasonable multi-model agreement on the position of thunderstorms during the afternoon/evening.

 

Showery outbreaks of rain within the base of the upper trough will swing across southern Ireland on Friday afternoon, into Wales and SW England overnight. A few isolated lightning strikes may be possible, but the risk in any one location is considered too low to warrant a SLGT - except perhaps towards the Channel Islands late in the night.

Edited June 26, 2020 by Gordon Webb
Updated With Latest Update

[cloudsabove]

First rumble here, rain falling, all windows open trying to get some cooler air in. Grey and overcast so nothing of note to see really as yet.

[Jamie M]

Some mammatus on the back-edge of the storm.

[Evening thunder]

Nothing here again.

Oh look it's good up north again today, and oh look it's good up north tomorrow.
The Outer Hebridies have had several rounds of storms more intense and longer lasting than anything I seem to be able to dream of here.

Storms away from the south coast started the day I was back to work so couldn't even chase in the SW 

Off to register my place in the no storms club.. If anyone says somewhere up north is the least thundery part of the UK.. think they have it wrong.

[ItIsGee]

40 minutes ago, Gordon Webb said:

Convective Weather Updated

Day 1 Convective Outlook

VALID 06:00 UTC Fri 26 Jun 2020 - 05:59 UTC Sat 27 Jun 2020

ISSUED 06:13 UTC Fri 26 Jun 2020

ISSUED BY: Dan

Excellent forecast! Lots of ifs and buts however a chase is on the cards. Model watching morning before now casting I suspect!

Edited June 26, 2020 by Supacell
Removed long quote

[Paul Sherman]

Our climate has shifted somewhat in the last 10-20 years and if you want to see Supercells in this country you have to go to the North West, Midlands And North East England. The days of the best storms in the South and South East are long past us now with a much drier arid climate down here where you can go 2-3 weeks without any rainfall at all and capping seems to be a much bigger problem these days

[Gordon Webb]

5 minutes ago, ItIsGee said:

Excellent forecast! Lots of ifs and buts however a chase is on the cards. Model watching morning before now casting I suspect!

this has been updated slightly , I have updated my post above accordingly

edit - link below for anybody not wanting to look above

Convective Weather

CONVECTIVEWEATHER.CO.UK

---

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

 

Edited June 26, 2020 by Gordon Webb

[Chris.R]

wow 5 CM hail. I can’t even think what that would be like to experience. The most I’ve ever seen is about 8–12 mm.

[Thunder and Lightning]

1 minute ago, Chris.R said:

wow 5 CM hail. I can’t even think what that would be like to experience. The most I’ve ever seen is about 8–12 mm.

Most I've seen is probably pea size! 

[ItIsGee]

Just now, Thunder and Lightning said:

Most I've seen is probably pea size! 

Had a few Donks in the USA but nothing here. 

[sparky1972]

a much cooler cloudy start here this morning, must be the crud left over from the storms down sth over night which will scupper our chances of storms today.

[James1979]

11 minutes ago, Paul Sherman said:

Our climate has shifted somewhat in the last 10-20 years and if you want to see Supercells in this country you have to go to the North West, Midlands And North East England. The days of the best storms in the South and South East are long past us now with a much drier arid climate down here where you can go 2-3 weeks without any rainfall at all and capping seems to be a much bigger problem these days

Spot on (used to live in your neck of the woods for most of that time) and more galling when you know there is so much action just across the channel on a regular basis. Another heatwave ending with not so much as a whimper here which was in line with my expectations. Fingers crossed for some home growns later but I wont hold my breath.

[tooby]

31 minutes ago, sparky1972 said:

Morning all, well after a quiet night its a very cloudy morning which will keep things storm free i would imagine.

Seems like things may be much better this afternoon for us sparky. See what the day brings

[I remember Atlantic 252]

seems to be moving north, not NE, missing here to the west and the east

[A.J]

'extremely underwhelming' sums it for here last night... absolutely nothing... disappointing, it has to be said 

[Tim Bland]

So for starters we had an Isle of Man clipper and a Kent clipper. Let’s hope the main course is better ! I think there could be a suprise desert for the south east tonight ....

[DIS1970]

Nothing here, looks like drifting just west of Wolves & clearing behind this band of cloud/showers.