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Supacell

Storms and Convective Discussion - 20th April 2019 onwards

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1 hour ago, Supacell said:

Tuesday nights action was all elevated within an elevated plume off the continent and was moving in a SW to NE direction, clipping only the south east of the UK. Sunday nights storms may be similar in that they would be elevated but may affect more of us with a more S to N movement. With increasing heat and humidity from Monday day time onwards, any storms that develop by day are likely to be surface based with CAPE right down to the surface as opposed to being only elevated. We are likely to get home grown storms in addition to those moving up from France.

A surface based storm brings a higher risk of severe weather than elevated (although elevated storms can still bring severe weather). It is unlikely that the CAPE being shown on GFS/NMM will be released to that extent, but even half of that CAPE with the jet stream overhead would be able to produce severe thunderstorms that are not often seen in the UK. Think 28th June 2012.

OK thanks for the explanation sounds like it could be memorable. 

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34 minutes ago, ChezWeather said:

Here's a good couple of sites with info on June 28th 2012 for anyone interested, to me this day is THE benchmark for UK storms.

https://www.stratusdeck.co.uk/28th-june-2012

https://hinckleyweatherblog.wordpress.com/2013/06/25/leicestershire-supercell-storms-of-28th-june-2012/

Thanks for this. I remember being at home as the skies darkened and I honestly thought the conservatory roof was coming in - the noise was phenomenal. We lived in a village just to the West of Melton Mowbray at the time so right "in the zone" according to the maps on these links.

A few hundred metres from our house is the old Asfordby Mine site which was (is) now used as a storage yard for a car dealer - they had literally hundreds and hundreds of brand new cars written off due to the damage to windows, roofs, panels etc

 

 

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Hinckley Hail!

On a side note, Camborne could be seriously moistening next week.

Edited by Mapantz

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52 minutes ago, ChezWeather said:

Here's a good couple of sites with info on June 28th 2012 for anyone interested, to me this day is THE benchmark for UK storms.

https://www.stratusdeck.co.uk/28th-june-2012

https://hinckleyweatherblog.wordpress.com/2013/06/25/leicestershire-supercell-storms-of-28th-june-2012/

thanks for those links, ties in with my own memories nicely 

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1 hour ago, A.J said:

28th june 2012 was a truly remarkable day.....the previous evening elevated thunderstorms erupted over SW England and Eire as a negatively tilted shortwave trough destabilized....early the following morning (28th) Elevated convection fired wuickly (around 7am) in the Welsh Marches which quickly became severe moving NE to affect the west midlands around mid morning (My village where Ilived at the time was subject to flash flooding)...This multicell cluster maintained strength to pass through Yorks and exited the NE coast early afternoon.....Meanwhile in the clearence behind, elevated storms firing further south (midlands) quickly rooted into the boundary layer became surface based, severe and then supercellular giving fist sized hail and several tornadoes through Leicestershire and Lincolnshire. This spectacular weather was realised with about 2000j/kg of both SB & MLCAPE to tap into, something more akin to tornadic outbreaks in the mid-west....Meanwhile in the SE of England, with plenty of SBCAPE in place but a strong inversion in place, it remained dry IIRC

I remember that event. Missed me completely. Storms took a sharp right turn into the Midlands and eastwards before they got as far N as here.

Was gutted.

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Oh no not that day again! The less said  about that imby the better. 

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1 minute ago, CreweCold said:

I remember that event. Missed me completely. Storms took a sharp right turn into the Midlands and eastwards before they got as far N as here.

Was gutted.

Snap. NW england’s worst ever storm day, and not in a good way! 

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Day 2 Convective Outlook

VALID 06:00 UTC Fri 21 Jun 2019 - 05:59 UTC Sat 22 Jun 2019

ISSUED 18:38 UTC Thu 20 Jun 2019

ISSUED BY: null

Residual cold pool across Scotland will gradually clear to the North Sea during Friday. However, scattered showers are still likely, though profiles reveal rather limited cloud depth and so ultimately very little lightning is expected.

http://www.convectiveweather.co.uk/forecast.php?date=2019-06-21

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2 hours ago, MetWeather said:

Anyone thinking we could get worse than Thunder Thursday? Its a thought in the back of my mind but i just know it will be across western Britain. Everyone says the South - East is the best for thunderstorms but they always happen elsewhere or weaken by the time they get to me! 😞 😞 😥

I have no doubt that the storms next week will be worse than Thursday and a much more widespread too. The CAPE amounts are enormous and was an area in Thursday's storms which could've done with being higher. End of next week particularly looks very dangerous.

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The clouds are something else this evening. 

040761C4-7C2E-456F-B5D2-D2025ADA9F88.jpeg

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1 minute ago, Ben Sainsbury said:

I have no doubt that the storms next week will be worse than Thursday and a much more widespread too. The CAPE amounts are enormous and was an area in Thursday's storms which could've done with being higher. End of next week particularly looks very dangerous.

I always make up imaginary tornado outbreak scenarios in my head, The end of this week might be one of those. Still hope it hits London.

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8 minutes ago, Ben Sainsbury said:

I have no doubt that the storms next week will be worse than Thursday and a much more widespread too. The CAPE amounts are enormous and was an area in Thursday's storms which could've done with being higher. End of next week particularly looks very dangerous.

High CAPE values are likely, but lets be real, we most likely aren't gonna see above 3,000j/kg CAPE.

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While I LOVE active storms, am I the only who doesn’t particularly want their car wrecked by large hail or roof blown off by a tornado?? Lol!

Give me an MCS with frequent lightning and banging thunder and I’m happy! US can keep their raging supercells thanks! 

Next week looking mighty interesting...let’s see where the models settle (when they do) 

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Recollecting something from several years ago, doesn't the GFS struggle with dew point temperatures - going too extreme? If that's the case, that's probably half the reason why it projects excessive CAPE values.

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The best by far or most severe in recent years for thunderstorms but with huge amounts of rain and severe flash flooding and its an easterly,next week we are in for it big time.

AVN_1_2018052700_1.png

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5 minutes ago, Mapantz said:

Recollecting something from several years ago, doesn't the GFS struggle with dew point temperatures - going too extreme? If that's the case, that's probably half the reason why it projects excessive CAPE values.

I'd imagine the GFS(P) would have ironed those issues out. 

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8 minutes ago, PerfectStorm said:

I'd imagine the GFS(P) would have ironed those issues out. 

The jury is out on that one. Meteorologists haven't been particularly pleased with it, and it has been showing some problems/biases. 
I don't pay much attention to the GFS CAPE values to be honest. If it shows bright colours and a trend emerges, then i'll wait for the higher resolution models to take over. It's nice having access to the UKV model now, i've been quite impressed with it, so far.

Edited by Mapantz

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Monday night to Tuesday morning is something we should keep an eye on too.

Edited by zmstorm

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Early forecast out from ConvectiveWeather

http://www.convectiveweather.co.uk/forecast.php?date=2019-06-23

 

Day 4 Convective Outlook

VALID 06:00 UTC Sun 23 Jun 2019 - 05:59 UTC Mon 24 Jun 2019

ISSUED 19:56 UTC Thu 20 Jun 2019

ISSUED BY: Dan

Longwave trough will linger over the Atlantic close to western Europe on Sunday, the southerly flow on its forward flank encouraging advection of an elevated mixed layer (EML) from the Spanish Plateau towards southern Britain by Sunday night.

Ahead of this, an isolated heavy shower / thunderstorm is possible during Sunday afternoon / early evening in a zone from Cen S England / S + W Midlands / Wales. However, despite profiles exhibiting reasonable speed and directional shear to aid organisation, one or more warm noses may significantly restrict cloud depth and so this is risk is treated with quite a low probability for now. A few showers are also likely in N and W Scotland, but with very little lightning expected.

However, main interest is during Sunday night. By Sunday evening, frontal rain will likely already be affecting parts of SW England and Ireland, and increasingly so across Wales and the Midlands - behind which advection of an increasingly warm, moist low-level airmass will occur during the overnight hours. A lead shortwave impulse in the strong southerly flow aloft will aid ascent, coupled with isentropic upglide as the EML arrives, to release the increasing amount of mid-level instability.

With time, scattered elevated thunderstorms - initially over parts of SW England / S Wales / S Ireland - will become more numerous and drift northwards as the night progresses. Strong deep layer shear should help thunderstorm complexes to grow upscale into an MCS (mesoscale convective system), particularly over Wales and the Midlands after midnight and then perhaps across northern England towards the latter stages of the night.

This extended outlook provides an overview of the most likely forecast evolution during this forecast period - however destabilising plume events are often fraught with uncertainty, and it is very likely certain aspects of the forecast will change as the event draws closer. However, provided guidance continues to remain relatively consistent, upgrades to higher threat levels are expected in future outlooks.

Edited by ChezWeather

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3 minutes ago, Snowyowl9 said:

The best by far or most severe in recent years for thunderstorms but with huge amounts of rain and severe flash flooding and its an easterly,next week we are in for it big time.

AVN_1_2018052700_1.png

Oh yes this night was absolutely immense! And it kick started 4 days of back to back intense thunderstorms for me!

I’ve attached the vid from the 27th only as I can’t squeeze the other ones on sadly (apologies for the angle!!)

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9 hours ago, Azazel said:

Good:)

My ideal scenario would be for beastly homegrowns to fire off to the SW of here and travel NE reaching maturity as they pass me. The best storms I've seen down here (structurally) have all been like that. Imports from France are great and all, especially for after-dark lightshows, but they're elevated with no defined structure and I want me a saucer shaped mothership with ground hanging gust-front please.

Good Lord you should take up creative writing! You even have me drooling at those last few words...

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Crazy CAPE/LI and still a negligible storm risk...

Screenshot_1.thumb.jpg.d7cd2cdd7130015f18edbf05ca662fe4.jpg.

Maybe a tad optimistic.

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Some nice late evening convection tonight...

cell1.thumb.jpg.84fea145b41507c58c87fdfd71aa4f49.jpg

image6.thumb.JPG.96a81dbd83a5760fcd94383c7153099a.JPG

image7.thumb.JPG.36896529dd2e48938dd38a193515ecbc.JPG

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Just now, poseidon said:

Crazy CAPE/LI and still a negligible storm risk...

Screenshot_1.thumb.jpg.d7cd2cdd7130015f18edbf05ca662fe4.jpg.

Maybe a tad optimistic.

I wouldn't be worried by what any computer generated forecasts are showing, keep an eye on what the people in the know are forecasting instead, i.e ConvectiveWeather, our very own Nick on Netweather, Tony Gilbert on UKWW, ESTOFEX and some of the very knowledgeable people in this thread etc. 

Exciting times ahead, with storm potential starting as early as Sunday by the looks of things! 

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