Storms and Convective discussion - June 2023

[TJS1998Tom]

Currently in North Yorkshire, Pickering so hoping for a good chance with storms, looking like a hot day with clear spells to start with which should help

[Aiden2012]

Love this

[The Tall Weatherman]

My 1st Convective forecast did relatively well and am back at it again. Would love some notes of advice which would happily be taken .

Sunday 25th of June 00z-23z Convective Forecast

During the morning hours widespread sunshine is expected with Temperatures locally reaching 30c in some areas around Central/Northern England. This should yield <1500 j/k SB Cape locally along with unseasonably strong 0-6km shear around 40 knots which is conducive for supercells if storms explode along the cold front. Although there is a huge amount of model discrepancy storms should be initiating around 13-14z if the cold front moves as planned (which probably won’t happen).

Storms will become relatively widespread around 15z and multiple discrete storms may fire to the north of Leeds which would contain the risk of Isolated large hail <4cm as aided by a straight hodograph and cold upper airs. Storms also have the risk of tornadoes (spin-ups) as they move east into a favourable unstable atmosphere with strong 0-6km shear and ramped up significant tornado parameters. As the afternoon goes by a few rogue storms may form further south towards Central England/ East Midlands around 15z if the cold front behaves and if temperatures of 28c can stay until late afternoon which the temperature needed for convection. Also further north near the Orkney islands a line of active storms may develop during the afternoon as suggested by the Arome and the 15z UKV.

Northern Ireland

Multiple thunderstorms may develop in and around Northern Ireland during the afternoon and any storms that mature might cause a spin-up tornado especially where convergence is maximised.

I am still actively learning about severe weather so don’t take this to seriously Am excited to see everyone on the forum tomorrow and good luck to anyone chasing ️

 

[Tamsin]

1 hour ago, Ben Sainsbury said:

... Has thunderstorms as far south as Peterborough late tomorrow evening.....

 

Aaaaggghhhhhh!!!! 

In a good way 

[Allseasons-Si]

Some dramatic sky's just recently here...

hoping for some dramatic storms tomorrow

[Southern Storm]

2 minutes ago, Allseasons-si said:

Some dramatic sky's just recently here...

hoping for some dramatic storms tomorrow

Lovely skies.

wishing everyone up north the best of luck for tomorrow

[James1979]

3 hours ago, Sunny76 said:

29 years ago, one of the best thunderstorms broke out across SE and Southern regions. A classic summer storm. 

The best thunderstorm in my 44 years... don't think I'll ever see it matched now.

[Sprites]

Convective Weather Forecast

Convective Weather

WWW.CONVECTIVEWEATHER.CO.UK

---

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

Day 2 Convective Outlook: Sun 25 Jun 2023

 

Day 2 Convective Outlook

VALID 06:00 UTC Sun 25 Jun 2023 - 05:59 UTC Mon 26 Jun 2023

 

ISSUED 20:31 UTC Sat 24 Jun 2023

 

ISSUED BY: Dan

 

An upper ridge will persist across much of Europe on Sunday, while a longwave upper trough slides eastwards across central/northern Britain. In the low-levels, a high Theta-W plume (>18C at 850hPa) will reside across Britain ahead of an active Atlantic cold front located N-S over Ireland at 06z Sunday. The exact evolution through the day carries some uncertainty and will depend on a number of factors phasing together at the right time. Assuming a degree of cloud-free skies across much of England, Wales and northern and eastern Scotland on Sunday morning, strong surface heating with temperatures reaching the high 20s in eastern England (in excess of 30C over East Anglia and SE England), combined with cooling of the mid/upper troposphere as the upper trough approaches, could potentially yield up to ~1,000 J/kg MLCAPE. Strengthening S/SW flow aloft (55kts at 500hPa, 85kts at 300hPa) will overspread Britain progressively through the day, creating an environment with effective shear of 30-40kts. Lee/pre-frontal troughing is expected to develop over northern England and across central/northern Scotland, aiding low-level convergence in the area and, in conjunction with orographic lift, providing the focus for deep convection to occur. This appears mostly likely just inland from the North Sea coast, with thunderstorms developing here and maturing as they drift close to the coast, and then offshore. Exactly how close to the coast initiation occurs is a little uncertain, with some CAM guidance suggesting that the vast majority of thunderstorms develop even just offshore. For now, catering for the idea of initiation further inland and then expanding in coverage near coastal areas. In addition, thunderstorms may also develop on the leading edge of the cold front across northern England aided also by PVA on the forward side of the upper trough, maturing as they drift northeastwards - and so it is possible some areas close to the North Sea coast could potentially have a couple of rounds of thunderstorms. 

 

Fairly unidirectional wind profiles near-parallel to surface boundaries suggests thunderstorms may develop into linear clusters, but also scope for splitting supercells if cells can remain a little more discrete. The environment would be supportive of hail 2-3cm in diameter in the most organised cells, and potentially wind gusts of 50-60mph (perhaps locally in excess of 60mph). Weaker forcing with southward extent, both at the surface and aloft, suggests thunderstorms may be more isolated towards the Midlands, Lincolnshire and Norfolk, but any that do occur here still have the potential to be severe. The lack of more substantial backing of the low-level winds, coupled with relatively high cloud-bases (at least initially) due to the deep, well-mixed boundary layer will tend to limit the tornado risk. However, close to the North Sea coasts where an onshore wind is likely for a time, and more discrete cells with longer residence time over land (allowing a better chance to become more organised, more especially over Yorkshire/Lincolnshire/NE Midlands), may pose the risk of an isolated tornado.

 

In the post-frontal environment, scattered showers and a few thunderstorms are also possible in Ireland/Northern Ireland beneath the upper trough axis, aided by a shortwave drifting eastwards, and these too could exhibit some organisation due to 20-30kts effective shear with perhaps some marginally-severe hail. While a general weakening trend is anticipated through the evening hours, a few showers/thunderstorms may drift across the Irish Sea into SW Scotland/NW Wales/NW England during the evening and night.

Edited June 24, 2023 by Sprites

[James1979]

Just now, Sprites said:

Convective weather forecast

Convective Weather

WWW.CONVECTIVEWEATHER.CO.UK

---

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

 

Haha every time I'm right on the very edge and same again with this one!! How does that happen? 

Quite surprised to see the risk so far south compared to recent forecasts, is there any chance of it squeezing a bit further south?

[TJS1998Tom]

Looks very promising for North Yorkshire tomorrow, looks like I may have timed going on holiday well if it all kicks off

[viking_smb]

33 minutes ago, Allseasons-si said:

Some dramatic sky's just recently here...

hoping for some dramatic storms tomorrow

just a quick question, these skies do they indicate storms then pls?

[Scuba steve]

2 minutes ago, viking_smb said:

just a quick question, these skies do they indicate storms then pls?

Early instability ahead of tomorrows cold front 

[CoventryWeather]

34 minutes ago, James1979 said:

Haha every time I'm right on the very edge and same again with this one!! How does that happen? 

Quite surprised to see the risk so far south compared to recent forecasts, is there any chance of it squeezing a bit further south?

Must admit - I like that forecast a lot. The recent UKV seems to have slowed the cold front down and having a few storms develop in the Midlands too. Don't know if models perhaps over-doing speed of it - we'll see in the morning.

[cheese]

Mackerel skies & virga over Leeds this evening 

 

[on the coast]

Latest BBC forecast dont seem that concerned about tomorrow with a normal warning issued.

 

[Aiden2012]

12 minutes ago, on the coast said:

Latest BBC forecast dont seem that concerned about tomorrow with a normal warning issued.

 

Hoping the lack of concern means it’s actually going to go the other way

[StormLoser]

Thank you Dan for your forecast.

Well, I may be in luck. I'm in Durham right now for an extended period, and tomorrow's forecast might break a long run of bad luck for me. Unless my personal high-pressure zone has accompanied me here. (Or 'Heat Dome' as some weirdos are calling high pressures, now).

If I get anything, I'll be sure to let you know!

 

 

[alexisj9]

44 minutes ago, StormLoser said:

Thank you Dan for your forecast.

Well, I may be in luck. I'm in Durham right now for an extended period, and tomorrow's forecast might break a long run of bad luck for me. Unless my personal high-pressure zone has accompanied me here. (Or 'Heat Dome' as some weirdos are calling high pressures, now).

If I get anything, I'll be sure to let you know!

 

 

I'm not sure it's what people call high pressure as such, just areas of heat that get stuck over an area for a while, normally on the west side of a high in the northern hemisphere, when above average temps get pumped up, like last summer when we hit 40, the heat dome built it's self up in Spain Portugal, and then got pumped up here for a few days.

Edited June 25, 2023 by alexisj9

[SarahWxm]

Mackerel skies over Wrexham tonight  

[P-M]

Well for once I'm slap bang in the moderate/ high risk area.  Already heading to 20c here, humid and I wait with baited breath! 

 

Sky keeps going from solid blue to this....

 

[Aiden2012]

So thoughts anyone, does the front seem to be going slower or faster than expected ?

[CoventryWeather]

Best of luck to everyone today. Not expecting anything down here, but I wouldn't mind an unexpected birthday present! Take care if you are chasing today.

[Zak M]

I’m heading to York for another storm chase - good luck everyone!

[The Tall Weatherman]

Have updated my risk map slightly to concern a new high risk and and a more western SVR to highlight the risk of multiple discrete storms that could possibly produce <4cm Hail in the strongest of cells. I have also overlayed multiple different models and somewhere just to the East of Scarborough seems most likely to see storms today ️

 

[P-M]

The heat and humidity is horrific this morning to be fair up here. It's not an enjoyable one. And the breeze is like a moist hairdryer.  

 

Roll on some cooler weather unless we get some decent dry heat

Sky is clearing again now which should aid heating (not that we need any more of it). 

 

Really hoping for a good storm this afternoon to clear the air.