Convective/Storm Discussion Thread - 1st August onwards

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Thu 24 Aug 2017 - 05:59 UTC Fri 25 Aug 2017

ISSUED 18:37 UTC Wed 23 Aug 2017

ISSUED BY: Dan

Showery bursts of rain close to western Scotland and Northern Ireland, and scattered showers in E/NE Scotland, could produce some isolated lightning. A few funnel clouds or weak tornado could be possible in eastern Scotland.

http://www.convectiveweather.co.uk/forecast.php?date=2017-08-24

[LightningLover]

BBC weather showing the potential for a SE clipper event  on Saturday night... Could be interesting.

 

EDIT: Tomorrow evening is a possibility too, with a fresh SE'erly wind developing!

Edited August 24, 2017 by LightningLover

[Marko1690]

I had to drive home on tuesday evening in northern Ireland, never seen lightning and rain like it, a pukka summer storm!

[Summer Sun]

Day 2 Convective Outlook

VALID 06:00 UTC Fri 25 Aug 2017 - 05:59 UTC Sat 26 Aug 2017

ISSUED 12:00 UTC Thu 24 Aug 2017

ISSUED BY: Dan

 

... SCOTLAND / NORTHERN IRELAND ...

Upper vortex will be located to the west of Scotland for much of Friday, with modestly-steep mid-level lapse rates covering Scotland and Northern Ireland. The forecast is complicated somewhat by cloud and showery outbreaks of rain along an occlusion, but ahead of and behind this feature there will be scope for some deep convection to develop in response to both diurnal heating and SSTs. Low-level convergence may play a role in N + NW Scotland, and this combined with a few hundred Jkg^-1 CAPE should allow some slow-moving heavy showers or thunderstorms to develop - and hence a low-end SLGT has been issued. Some localised surface water issues may evolve given the slow-moving nature of the showers. A few weak funnel clouds or a break tornado may also be possible from this activity.

 

As the upper vortex and associated steeper lapse rates moves eastwards overnight, so the risk of some isolated lightning continues, though limited somewhat by nocturnal cooling of surface temperatures and areas of more stratiform rain associated with old occlusions.

 

... SE ENGLAND ...

As an Atlantic upper trough digs south to the west of Iberia, becoming a cut-off low, the flow over western Europe will back during Friday, allowing advection of a higher WBPT airmass across the English Channel and into SE England. Still some uncertainty, but there is potential for some elevated showers or thunderstorms to develop through isentropic lift over the eastern half of the English Channel late Friday afternoon into the evening, which may get close to both SE England and the Channel Islands. Too much uncertainty at present for any upgrades to SLGT, with the vast majority of NWP output keeping any activity over mainland France.

 

... N / NE ENGLAND ...

As the upper vortex over Scotland drifts eastwards on Friday night, the upper flow will strengthen on the forward side, with a shortwave perhaps engaging with the moisture axis over eastern England. Some showery outbreaks of rain may develop, largely from the mid-levels, which could produce some isolated lightning - moreso as it exits to the North Sea. In fact this area of development then becomes the focus for some potentially quite active lightning activity over the North Sea during Saturday.

 

http://www.convectiveweather.co.uk/forecast.php?date=2017-08-25

[Nick F]

Storm & Convective Forecast

Issued 2017-08-25 08:06:27
Valid: Friday 25 Aug 6am to Saturday 26 Aug 6am

Day 1 Convective /Storm Forecast

Synopsis

An upper and collocated surface low to the west of Scotland will gradually drift east across Scotland during the forecast period. Heavy showers and thunderstorms are likely across Scotland and N. Ireland, then perhaps over N England overnight.

... SCOTLAND, N of Rep. of IRELAND and N. IRELAND ...

Upper low close to NW Britain will create steep lapse rates and create large scale ascent which will support scattered heavy showers and thunderstorms away from frontal cloud and rain areas. Weak vertical shear will mean severe weather is unlikely, though any heavy showers/storms will be slow-moving leading to a risk of localised flooding where they pass. Showers/storms may also produce small hail and gusty winds. Light winds aloft and surface convergence may produce funnel clouds or even a brief/weak tornado with stronger updrafts. Showers and isolated storms may continue overnight as they drift east across Scotland with the upper/surface low, lightning activity may increase along east coast as cells move out over N Sea with warm SSTs (sea surface temps) creating bouyancy.

... N ENGLAND ...

As upper low crosses Scotland tonight, pool of steep lapse rates generated over relatively warm Irish Sea SSTs will support heavy showers and a few thunderstorms pushing inland and east across N England overnight. with a risk of localised flooding from stronger cells. Lightning activity may increase as cells move out over the N Sea and over warm SSTs.

Issued by: Nick Finnis

[Flash bang flash bang etc]

Hmmm - conflicting information regarding the chance of imports and / or clipper in the far SE later.

Would love a distant overnight display

[Nick F]

15 minutes ago, Flash bang flash bang etc said:

Hmmm - conflicting information regarding the chance of imports and / or clipper in the far SE later.

Would love a distant overnight display

Looks more unlikely now, the BBC/Met office forecasts were hinting as such last few days, but now just going for a few 'sharp' showers clipping east Kent, whereas most models not showing anything.

[Flash bang flash bang etc]

Some interesting skies over dunsfold

[Summer Sun]

Day 1 Convective Outlook

VALID 06:00 UTC Mon 28 Aug 2017 - 05:59 UTC Tue 29 Aug 2017

ISSUED 07:58 UTC Mon 28 Aug 2017

ISSUED BY: Dan

Both areas of interest are reserved primarily for Monday night.

... S / SE ENGLAND ...

Subtle forcing approaching from the SW could be enough to destabilise the Theta-E ridge as it advects NE-wards through the night hours. There is a lot of uncertainty as to whether this destabilisation occurs and the exact areas most likely affected, but if it does then a few elevated thunderstorms would be possible during the early hours of Tuesday, potentially quite electrically-active, these then persisting beyond this forecast period into East Anglia on Tuesday morning. A low-end SLGT has been issued for now, but this may need adjusting (or removing) based on trends through the day.

 

... N / NW SCOTLAND ...

Behind the cold front, broad upper trough approaching from the Atlantic will introduce steeper lapse rates and a deep convection regime to northwestern areas towards the end of Monday night. Some sporadic lightning and gusty winds will be possible from scattered heavy showers.

 

http://www.convectiveweather.co.uk/forecast.php?date=2017-08-28

[Stuart]

Day 1 Convective Outlook

VALID 06:00 UTC Mon 28 Aug 2017 - 05:59 UTC Tue 29 Aug 2017

ISSUED 07:58 UTC Mon 28 Aug 2017

ISSUED BY: Dan

Both areas of interest are reserved primarily for Monday night.

 

... S / SE ENGLAND ...

Subtle forcing approaching from the SW could be enough to destabilise the Theta-E ridge as it advects NE-wards through the night hours. There is a lot of uncertainty as to whether this destabilisation occurs and the exact areas most likely affected, but if it does then a few elevated thunderstorms would be possible during the early hours of Tuesday, potentially quite electrically-active, these then persisting beyond this forecast period into East Anglia on Tuesday morning. A low-end SLGT has been issued for now, but this may need adjusting (or removing) based on trends through the day.

 

... N / NW SCOTLAND ...

Behind the cold front, broad upper trough approaching from the Atlantic will introduce steeper lapse rates and a deep convection regime to northwestern areas towards the end of Monday night. Some sporadic lightning and gusty winds will be possible from scattered heavy showers.

 

http://www.convectiveweather.co.uk/forecast.php?date=2017-08-28

[NO LONGER POSTING]

Just seen the above come up on my Facebook.. So much difference in models and kind "out of nowhere" thing for the SE..

AROME

ARPEGE

NET WEATHER

 

EURO 4

HILRAM

  

Let the battle of the HIGH RES commence place your bets please, place your bets

I would like to go with the AROME idea of course, but it's not great at performing in these situations so will go with yes storms, but im not convinced yet on them making it onto our shores.. But after what could be the warmest Bank holiday on record, surely that is a great way to end it with a thunderstorm!

[Andy Bown]

Well it's not so much of a surprise as in the set up is pretty ideal with heat building ahead of a very slow moving cold front, almost a plume situation.

Just 4 days ago the cold front was forecast to be crossing Southern England this afternoon.

[LightningLover]

Im keeping an eye on things for later!

[NO LONGER POSTING]

24 minutes ago, Andy Bown said:

Well it's not so much of a surprise as in the set up is pretty ideal with heat building ahead of a very slow moving cold front, almost a plume situation.

Just 4 days ago the cold front was forecast to be crossing Southern England this afternoon.

Agree but the conditions are not favorable. Hence why there is so much IF involved for later today 

[LightningLover]

Convective weather's statement has got me excited! 

"a few elevated thunderstorms would be possible during the early hours of Tuesday, potentially quite electrically-active"

[tomp456]

Can't see any storms tonight, this years quota was used up fully on 19th July.

[LightningLover]

2 minutes ago, tomp456 said:

Can't see any storms tonight, this years quota was used up fully on 19th July.

Dont lose hope! even if they stay in the channel, we will get a good show!

[alexisj9]

21 minutes ago, tomp456 said:

Can't see any storms tonight, this years quota was used up fully on 19th July.

Didn't get anything from that one, however dito, but on the 28th may.

[Marko1690]

Over here in northern ireland its quite muggy and close with night time temps to come down to 6 or 7 degrees, chilly for a thunderstorm lol

[Team Jo]

Hmmm. Things seem to be pepping up in NW France, and we have just gone from almost entirely blue sky, to cloud, and what feels like a bit of destabilizing kicking in.

I suppose I'm being greedy, it's been very warm here today!

[NO LONGER POSTING]

hmmm something over Northern France which is a good sign that the conditions are favorable thier side.. Lets see how things go. Don't expect anything this side of midnight to fire for us though IF it does.

The more interesting thing, is currently, the only high res to pick these up is the AROME... 

 

 

[LightningLover]

Keep an eye on those cells in N France, could be a good sign for later!

[Nick F]

06z AROME breaks out heavy showers (maybe thundery?) across SE corner early Tuesday morning

 

00z ECMWF had some rainfall across SE England between 06z and 12z Tuesday too.

Some weak CAPE spreading NE across the SE on Tuesday morning on both AROME and EC, but GFS shows no CAPE or rainfall what so ever.

Be interesting who's right in the end, AROME is normally quite good a picking up these elevated destabilisation convective situations.

Edited August 28, 2017 by Nick F

[NO LONGER POSTING]

So here we are.. The saying "here we go again" springs to mind.. Will we watch Northern France light up like normal or will the weather gods put the cherry on top of the cake in terms of the weather we have experienced in the south over the past few days!

[LightningLover]

12 minutes ago, Surrey said:

So here we are.. The saying "here we go again" springs to mind.. Will we watch Northern France light up like normal or will the weather gods put the cherry on top of the cake in terms of the weather we have experienced in the south over the past few days!

28-29th may?