Convective/Storm Discussion Thread - 1st August onwards

[Mapantz]

Rule of thumb with GFS CAPE charts; halve all values shown.

[Mokidugway]

I'm shure I've seen 4000 plus on GFS huge overcook on them but still interesting . 

[Flash bang flash bang etc]

39 minutes ago, Ben Sainsbury said:

Absolute stormgasm charts on the GFS 12z!

These are the charts I live for aha, could be some very active buggers should any form!

Have Thursday and Friday off - was an event that got cancelled - so if this materialises i’ll be loading up on Ribena, mini sausage rolls, peanuts, baby bell cheese and a bottle of golden ale on weds night...  ???

[Ben Sainsbury]

1 hour ago, Mokidugway said:

I'm shure I've seen 4000 plus on GFS huge overcook on them but still interesting . 

Not far off lol

1 hour ago, Mapantz said:

Rule of thumb with GFS CAPE charts; halve all values shown.

See I always thought this was dependent on cloud cover, unless I'm completely wrong.

Had a peak at the Netwx Model for same time frame, seems to be half of that of GFS lol. Guess I am wrong all learning!

Edited April 12, 2018 by Ben Sainsbury

[Nick F]

3 hours ago, Flash bang flash bang etc said:

It’s been grey across Surrey Hills, Thames valley and up into north London all day (I know this because I’ve had to drive everywhere) but my question is:

• will this affect our chances later?

Well chances are slim for storms away from Kent and E Anglia, but the grey skies are not really a contributory factor to lack of, as SE England storm risk will be imported from France tonight, if they make it across the sea they will be elevated.

[Mapantz]

26 minutes ago, Ben Sainsbury said:

Not far off lol

See I always thought this was dependent on cloud cover, unless I'm completely wrong.

Had a peak at the Netwx Model for same time frame, seems to be half of that of GFS lol. Guess I am wrong all learning!

I always kept meaning to save some GFS charts that showed huge CAPE values, and hi-res charts/realtime data for a post comparison - keep forgetting! I think it  happened last year and the year before that?! silly CAPE values were being projected by the GFS.. a day before the event, the hi-res models were in the realms of maxing at circa 900jk/g. The Netweather v4 radar could also overlay CAPE, and nearly every time, it was more than half of the values of the GFS. To be fair, if the event does stay consistent, the GFS will bring these values down as it get's nearer the time. Things still went POp! though.

Edited April 12, 2018 by Mapantz

[Flash bang flash bang etc]

30 minutes ago, Nick F said:

Well chances are slim for storms away from Kent and E Anglia, but the grey skies are not really a contributory factor to lack of, as SE England storm risk will be imported from France tonight, if they make it across the sea they will be elevated.

Still learning a lot about this side of things - but do elevated storms carry their energy from earlier surface heating elsewhere then?

Thanks for the info tho - good to hear we still have a small chance of something ?

[Windblade]

Some large cells heading across the channel heading towards kent now but no sparks. I think the sea is just too cold at the moment. Still hopeful however that these cells will pass over, as I adore the sound of rain pounding on the roof and windows late at night. So relaxing. 

Edited April 12, 2018 by Windblade

[Summer Sun]

Day 1 Convective Outlook

VALID 06:00 UTC Fri 13 Apr 2018 - 05:59 UTC Sat 14 Apr 2018

ISSUED 17:23 UTC Thu 12 Apr 2018

ISSUED BY: Dan

... NE ENGLAND / E +  NE SCOTLAND / NORTHERN ISLES ...

Elements of showery rain, perhaps with some weakening elevated thunderstorms, will be ongoing Friday morning over the North Sea, and occasionally drifting inland. While lightning activity will likely be isolated, some mid-level instability will still exist for a time, and so a LOW threat level has been issued to cover this (relatively low) risk. Northern Isles appear at greatest risk for some isolated lightning associated with the plume axis over the North Sea.

 

... SW ENGLAND ...

Provided sufficient cloud breaks can allow some reasonable insolation, marginal instability and orographic / sea breeze forcing may allow a couple of isolated but locally heavy showers to develop on Friday afternoon. Some isolated lightning will be possible, with the main threat localised surface water issues given slow storm motion.

http://www.convectiveweather.co.uk/forecast.php?date=2018-04-13

[alexisj9]

21 hours ago, Nick F said:

Well chances are slim for storms away from Kent and E Anglia, but the grey skies are not really a contributory factor to lack of, as SE England storm risk will be imported from France tonight, if they make it across the sea they will be elevated.

Well heavy rain made it across, didn't get any storms though

[Flash bang flash bang etc]

Evening sky looks quite pre-storm tonight. Shame we have nothing forecast 

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Sat 14 Apr 2018 - 05:59 UTC Sun 15 Apr 2018

ISSUED 18:55 UTC Fri 13 Apr 2018

ISSUED BY: Dan

Diurnal heating and subtle low-level convergence may be sufficient to allow an isolated shower or two to develop during the late afternoon / evening hours on Saturday. Given marginal instability, dry forecast profiles and very little shear, any convection that manages to develop will likely struggle to grow in height, and so the lightning risk is considered very low (almost below our 5% threshold).

Scattered thunderstorms are likely to develop over NE France on Saturday afternoon, which may slowly drift across the English Channel during the evening hours - while sufficient weakening is expected as they encounter much colder SSTs, subtle forcing as a shortwave drifts NE may allow some showery bursts of rain to drift over SE England, albeit with a rather low risk of lightning. Hence parts of Kent / Sussex / coastal Essex have also been included in the LOW threat area.

 

http://www.convectiveweather.co.uk/forecast.php?date=2018-04-14

[Flash bang flash bang etc]

Any reason to ignore those storms on the French coast? Only a bit of sea stopping them... ? 

[Flash bang flash bang etc]

Sparks in the channel! ⚡️ 

[Flash bang flash bang etc]

h

[Flash bang flash bang etc]

Almost cloudless here yet that finger of heavy rain is bearing down on us like a moth toward an IOT lighting festival

[Jordan S]

2 hours ago, Flash bang flash bang etc said:

h

Indeed some of them I think will make it across the channel but probably not many and pretty weak thunderstorms too but I've got a watch out for southern parts this evening.

[Mapantz]

They'll just die out as the sun goes down.

[Jordan S]

2 minutes ago, Mapantz said:

They'll just die out as the sun goes down.

True although still a couple hours until then and some isolated heavy showers/weak thunderstorms will break out before then across southern parts but will be very isolated I think.

[Ben Sainsbury]

6 minutes ago, jordan smith said:

True although still a couple hours until then and some isolated heavy showers/weak thunderstorms will break out before then across southern parts but will be very isolated I think.

Yeah, still a couple hours of sun. The batch of storms in N France formed in connection of a trough moving northwards. This should initiate a few showers across south midlands over the next hour or two (what we're seeing already) though nothing substantial. Still some half decent convection to the NE of here.

[Jordan S]

14 minutes ago, Ben Sainsbury said:

Yeah, still a couple hours of sun. The batch of storms in N France formed in connection of a trough moving northwards. This should initiate a few showers across south midlands over the next hour or two (what we're seeing already) though nothing substantial. Still some half decent convection to the NE of here.

Yes there are a few heavy showers developing near reading and just south of Aylesbury and Oxford. They will continue developing and pushing northward in the next hour or so..

[Flash bang flash bang etc]

Surely that stuff from France and in the channel will get chance to interact with the surface warming as it hits land?

We’ve had about 5hrs unbroken sunshine here

[Jordan S]

4 minutes ago, Flash bang flash bang etc said:

Surely that stuff from France and in the channel will get chance to interact with the surface warming as it hits land?

We’ve had about 5hrs unbroken sunshine here

Yes there's a chance but the storms over the channel will mostly die out over the channel plus there isn't much time until the sun has gone which will hinder any real development although isolated thunderstorms/heavy showers will and are breaking over land  as a result of the warm land mass with a marginally unstable air mass/ Kent clipper is a possibility too this evening but nothing too significant is expected.

Edited April 14, 2018 by jordan smith

[Flash bang flash bang etc]

1 minute ago, jordan smith said:

Yes there's a chance but the storms over the channel will mostly die out over the channel plus there isn't much time until the sun has gone which will hinder any real development although isolated thunderstorms/heavy showers will are breaking out as a result of the warmest land mas with a marginally unstable air mass/ Kent clipper is a possibility too this evening but nothing too significant is expected.

Thing that frustrates me (again) is that the areas around the M4 that are now seeing some showers breaking out haven’t had the hours of solar heating we just had (sat24 showed general cloud cover this afternoon) and yet THEY get the convection.

We have a showery front moving in from the south where it’s been shown to have convective potential, but - yet again - some baffling science dictates that we get nothing, and as usual it all stalls and peters out (like it’s doing right now).

There is ALWAYS a reason we don’t get the goods - which in this case isn’t anything special - but it’s a good example of the trend that I imagine (like previous years) is gonna blight our storm chances time and time again during the coming summer. 

i just know it and it’s already bothering me. I don’t need excuses for the weather misbehaving - it’s not like we get hundreds of thousands of chances. It’s not like we live in Arkansas!

 

(On the plus side - it’s been a lovely afternoon)

 

 

...Anyway, no rain yet.

[Jordan S]

1 minute ago, Flash bang flash bang etc said:

Thing that frustrates me (again) is that the areas around the M4 that are now seeing some showers breaking out haven’t had the hours of solar heating we just had (sat24 showed general cloud cover this afternoon) and yet THEY get the convection.

We have a showery front moving in from the south where it’s been shown to have convective potential, but - yet again - some baffling science dictates that we get nothing, and as usual it all stalls and peters out (like it’s doing right now).

There is ALWAYS a reason we don’t get the goods - which in this case isn’t anything special - but it’s a good example of the trend that I imagine (like previous years) is gonna blight our storm chances time and time again during the coming summer. 

i just know it and it’s already bothering me. I don’t need excuses for the weather misbehaving - it’s not like we get hundreds of thousands of chances. It’s not like we live in Arkansas!

 

(On the plus side - it’s been a lovely afternoon)

 

 

...Anyway, no rain yet.

You say that but I live in Aylesbury just north of the m4 and there's been unbroken sunshine since well before midday and there are a few isolated showers heading our way but bear in mind unbroken sunshine does not mean you'll get thunderstorms or showers because you need several other ingredients which we are absent of today tbh which explains why hardly anything has happened. Pressure is quite high which doesn't help.