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

[NO LONGER POSTING]

Im not convinced on this one, I don't think this time it will happen 

[Harry]

Along similar lines to you Surrey. I've not spiked with any form of anticipation with this potential today.

[Supacell]

The various charts I have looked at this morning does show that all the real energy is where the hottest temperatures are, which is in the SE/EA. Rainfall is however predicted to be mainly further north and west across most of the rest of England. There are still differences between models on where the rainfall will occur, but it will likely follow the path of a weak cold front draped somewhere through central areas. Unfortunately though, it could just be plain old rain if the convective potential is all trapped in the SE. Meanwhile, in the SE and EA, there is strong capping and if this can't break then it will remain dry. If the cap breaks then expect some fun and games, but it looks to be a big if.

I have to admit it makes me nervous that Estofex do not highlight a risk at all for the UK today. It would indicate that they see the scenario I have eluded to above whereby any potential is trapped under a strong cap in the SE. The BBC mention the risk of lightning and thunder overnight with some areas of rain moving NE along the cold front. I am not convinced that the lightning and thunder will be in the same place as the rain though. I foresee some patchy rain moving through central parts and some flashes of elevated lightning to the SE of the rain but in mostly dry conditions on the ground.

Tomorrow looks the better probability with some models pushing MLCAPE quite far north with our resident cold front pepping up and turning progressively more thundery. BBC make more of the thundery risk tomorrow too. I will await the expert views on tomorrow as we go into the latter part of today.

[Norfolk Sheep]

Can't say this year has delivered here (what happened in July? Did I miss something?) Even Holland didn't come through with anything - boo hiss! I think the chances of a repeat of 17th/18th July 2015 are remote but I would love to be able to sit under another train and get some more shots like this.....

Edited August 24, 2016 by Norfolk Sheep
addition

[Chris K]

As expected Saturday's potential, which I had more interest in, is ever more restricting itself towards the continent thanks to the LP to our West forcing away the plume more quickly. A couple more days of model runs to get through yet...

Based only on the NetWx-SR 0z run, Thursday into Friday looks very wet for Wales, Central/Northern parts of England. Could be some interest here if there is enough energy.

There does seem to be a chance of elevated storms tonight pushing up from the South moving N/NE, but again the timings are weird this year with convective rainfall initiating Midlands Northwards during Thursday. Used to get decent storms moving onto the S coast late evening. Now it's 3-6AM...

So potential is there but it remains to be seen whether this gives anyone an electrical display. I suspect tonight/early tomorrow any lightning would be quite isolated? We will see.

 

 

Edited August 24, 2016 by Chris K

[Stuart]

Day 1 Convective Outlook

VALID 06:00 UTC Wed 24 Aug 2016 - 05:59 UTC Thu 25 Aug 2016

ISSUED 08:03 UTC Wed 24 Aug 2016

ISSUED BY: Dan

Most plume events carry an element of uncertainty, but this particular event appears to have greater than average uncertainty. Even at this stage there is a large spread of possible outcomes amongst various models. There is good agreement amongst NWP to keep the warm, moist plume across England capped during Wednesday daytime, despite a build-up of SBCAPE in response to strong heating - particularly across E Anglia / Home Counties / SE England / CS England. Whilst currently unexpected, should the cap be eroded locally, then a strong to perhaps severe thunderstorm would be possible capable of large hail, given strong deep layer shear and high values of storm relatively helicity.

 

The most likely evolution, however, is an increase in elevated convection to occur as the warm plume begins to destabilise, beginning over the English Channel and environs (Dorset/Devon etc) early-mid afternoon, with activity generally migrating NNE-wards through the evening and night hours. Initially, given hot, dry surface air, a lot of virga with not much precipitation reaching the ground is expected, but still scope for some (at least sporadic) lightning from elevated thunderstorms. That said, upper forcing is rather weak much of the time, and a low-end SLGT has been issued to highlight this risk, but with some uncertainty over the exact areas that may be affected, and hence a shift to the W or E may be possible in any later updates.

 

Later in the night slightly stronger forcing arrives from the southwest, but by this stage the most favourable conditions for thunderstorms will have shifted east - and so a broad LOW threat level is issued for an uptick in precipitation coverage later in the night over the Midlands for example, but questionable as to how much lightning activity will be associated with this.

 

The true extent of lightning activity (in terms of frequency and coverage) is a little unclear at this time, and at this stage does not look to be as frequent/widespread as the 19th-20th July 2016 events.  Any thunderstorm activity that does develop on Wednesday night will continue to track NNE-wards beyond this forecast period into Thursday morning.

 

Scattered showers and a few weakly-electrified thunderstorms will also be possible over W Scotland and western fringes of Ireland on Wednesday night.

 

http://www.convectiveweather.co.uk/forecast.php?date=2016-08-24

[Willsy]

12 hours ago, Supacell said:

It's on topic as far as I can see... a video of a thunderstorm, and a fantastic one at that. As you say it is hard to believe this was England. I've never seen CG's raining down that frequently in this country. I know that night was an impressive night though, especially across the south coast. I am thinking it is the 4th July last year as at the end of the video there are links to other videos for this date.

If I see something even close to that tomorrow night I will be forever satisfied!

It was in Friday the 3rd into the 4th maybe a once in a lifetime storm. The frequency of lightening was unreal on lightening maps at some points there were 10 or more strikes at once from it. I bet you will man

[Willsy]

9 hours ago, Speedway Slider said:

Shocked as well, how far away were you when you shot this? Can't believe how many people are just sitting/standing around watching/filming it all.... Surely, that was damn dangerous, was it coming towards you?

That was an absolute belter.....!!!

I didn't film it lol found it last night reminiscing on YouTube. It's crazy ain't it I wouldn't wanna be outside in that. To me it was moving north north east. Hopefully we get something like that over the next few days but I doubt it now 

[Nick F]

Storm & Convective Forecast

Issued 2016-08-24 09:26:16

Valid: 24/08/2016 0600z to 25/08/2016 0600z

CONVECTIVE/STORM FORECAST - WEDS 24TH-AUGUST-2016

Synopsis

Amplifying upper trough to the west of the British Isles will continue to advect a plume of hot and humid air north across south and east England on Wednesday ahead of a slow-moving cold front lying between NE and SW England. Although the cold front is inactive for now, a wave will develop from the SW this evening and overnight, bringing an increased risk of thundery downpours across southern, central and eastern England tonight.

… S and E ENGLAND, SE WALES, MIDLANDS …

Hot and humid airmass across S and E England on Wednesday will be strongly capped by upper ridge on near continent, despite models indicating several 100 j/kg CAPE building this afternoon thanks to strong surface heating.

However, slowly falling heights from the west and shortwave upper trough, visible on WV imagery, triggering storms across NW Iberia this morning, will move NE toward S England later. This increase in upper forcing and subsequent re-activation of cold front as it develops a wave moving NE will allow the development from this evening of isolated elevated thunderstorms pushing NE from the English Channel and central southern England up through the Midlands towards Yorks, Lincs and Norfolk. There is some uncertainty over eastern extent of these storms, with some isolated storms possible across SE England too later in the night.

Some organisation into multicell clusters of storms is possible, given strengthening mid-upper SWly flow aloft and 40-50knts of deep layer shear. However, much of the rain falling from these elevated storms may evaporate before it reaches the ground, given very warm dry air at the surface, so rainfall will not pose much of an issue until perhaps later in the night across The Midlands and NE England as moister air and greater forcing moves in. Frequent cloud-to-ground lightning and perhaps isolated strong wind gusts will be the main hazard from these storms. Have not issued a categorical severe risk for storms overnight into Thursday for now, but may later today if storms become organised.

 

Issued by: Nick Finnis

[Thunderstruck]

Not quite sure what to make of this. Think we'll have to wait and see...

[Luke Best]

On 19/07/2016 at 19:19, Thundery wintry showers said:

 

On 20/07/2016 at 17:11, Harry said:

1 hour ago, Willsy said:

It was in Friday the 3rd into the 4th maybe a once in a lifetime storm. The frequency of lightening was unreal on lightening maps at some points there were 10 or more strikes at once from it. I bet you will man

 

[tomp456]

Really not holding out for much today or tomorrow here, mother nature be like 

 

 

Edited August 24, 2016 by tomp456

[TheToastPeople]

Sat24 already has me drooling!

[alexisj9]

 

6 minutes ago, TheToastPeople said:

Sat24 already has me drooling!

Like I said over in the SE thread, it start clear blue but now there is some slight build up of cloud even this far east. It's nothing major but I didn't expect it at all.

[alexisj9]

9 minutes ago, TheToastPeople said:

Sat24 already has me drooling!

Can't seem to get into sat24 here,

[Dami]

Afternoon toast, hope you are well  Nope can't get into sat24 either. 

Not expecting anything, but hubs is cooking chicken strips and quick french fries for lunch. Just need a glass of something to make it pub lunchy. Beautiful day if i may say so and no i'm not checking every five minutes to see if anything is building. Getting a light breeze now too. yummy.

[jtay]

11 minutes ago, alexisj9 said:

Can't seem to get into sat24 here,

I noticed that the other day. They've updated the URL to http://en.sat24.com/en/eu

without forwarding the old one to the new site.

[Dami]

1 minute ago, jtay said:

I noticed that the other day. They've updated the URL to http://en.sat24.com/en/eu

without forwarding the old one to the new site.

ah there it is many thanks!

[alexisj9]

2 minutes ago, jtay said:

I noticed that the other day. They've updated the URL to http://en.sat24.com/en/eu

without forwarding the old one to the new site.

lol a bit silly.

[Summer Sun]

Severe chance of thunderstorms

Day 2 Convective Outlook

VALID 06:00 UTC Thu 25 Aug 2016 - 05:59 UTC Fri 26 Aug 2016

ISSUED 09:23 UTC Wed 24 Aug 2016

ISSUED BY: Dan

This is an advance forecast issued to highlight the potential for thunderstorms - but given the current lead time, it is likely some aspects will be changed as confidence increases towards the event.

A messy situation is expected on Thursday with various areas of dynamic and convective precipitation running northeastwards across England and Wales, as more widespread destabilisation of the warm, moist airmass takes place as the Atlantic trough approaches. A broad SLGT has been issued, but it is worth noting there is some uncertainty as to how active (lightning-wise) some of this convection will be, and it is quite likely some areas will remain lightning-free - but given the uncertainty it is impossible to be any more precise as to the areas most likely to be affected at this stage. The main threat will be the risk of local flash flooding given high moisture content.

If sufficient insolation can develop (which is questionable given the likely extensive cloud cover) to break the quite significant capping inversion, there may be scope to develop surface-based thunderstorms. Given the environmental conditions, these could be severe with large hail up to 3.5-4.0cm in diameter, and perhaps a tornado (along with the associated risk of flash flooding also). This scenario is given a low probability at the moment, but we have issued a SVR to highlight the areas that may be affected should an overlap of ideal conditions occur.

Across Scotland and Ireland / Northern Ireland, the approaching Atlantic upper trough and associated cool mid-levels, atop warm SSTs and diurnally-heated land, will allow a few scattered showers and thunderstorms to form on Thursday and lingering into Thursday night. Some parts may need an upgrade to SLGT.

http://www.convectiveweather.co.uk/forecast.php?date=2016-08-25

Edited August 24, 2016 by Summer Sun

[A.J]

just had a quick glance at sat24 (thanks for the updated link jtay).....storms forming over northern biscay are tracking NNE.....currently areas in a line east of bristol and west of London and northeastwards look to be a good bed for elevated convection/storms should they develop further this evening

[Mapantz]

Getting close to the 19°C dew point here, it definitely feels like it! It reminds me of 2013 a bit.. I remember a random cloud appearing to the Southwest, and it just grew, and turned electrified. It wasn't a HP cell, but it was a great sight nonetheless.

[Speedway Slider]

What will actually need to happen to break/breach the cap (locally)?

Thanks.... in advance peeps.

[weirpig]

40 minutes ago, ajpoolshark said:

just had a quick glance at sat24 (thanks for the updated link jtay).....storms forming over northern biscay are tracking NNE.....currently areas in a line east of bristol and west of London and northeastwards look to be a good bed for elevated convection/storms should they develop further this evening

I Must say i was quite shocked at  that from sat24  some areas could be right in the firung line   as you say slightly  to the east of Bristol uptowards the Humber., Wash area   might be more potent than i thought. Below is the lightening map  not to be taken as gospel 

Edited August 24, 2016 by weirpig

[Mapantz]

It should have been like this once a fortnight throughout this Summer..