Storms and Convective discussion - 10th April 2020 onwards

[oliverek7]

Viewsurf - Webcams HD plage - Arcachon - Live

WWW.VIEWSURF.COM

---

Viewsurf, leader européen de la webcam HD touristique live et différée, plage - France - Aquitaine - Arcachon - Live

 Watching some lovely lightning displays on the Archachon webcam as the thundery front approaches the west coast of France 

[Ben Sainsbury]

7 minutes ago, Oliver Wyndham-lewis said:

Viewsurf - Webcams HD plage - Arcachon - Live

WWW.VIEWSURF.COM

---

Viewsurf, leader européen de la webcam HD touristique live et différée, plage - France - Aquitaine - Arcachon - Live

 Watching some lovely lightning displays on the Archachon webcam as the thundery front approaches the west coast of France 

Might actually be the best lightning display I've ever seen on a webcam.

[toggerob]

Just a shame it's one of those cam's that pan around, ugh, keep it in one spot 

[Flash bang flash bang etc]

Curious to know how far into the channel this might get, although I have a feeling that more stable air will be well in place by the time it gets anywhere near our shores

[Zak M]

Got some pictures from the Arcachon cam.

[oliverek7]

1 minute ago, Zak M said:

Got some pictures from the Arcachon cam.

Lovely stuff!

[Zak M]

Still a bit uncertain about this but there is a chance of the odd lightning strike tomorrow as heavy showers from (I'm still learning so correct me if I'm wrong but it looks like an occluded front?) moving north. Some heavy showers could also form in NW France and might drift up north during Wednesday evening and night.

Edited May 5, 2020 by Zak M

[oliverek7]

Starting to look more promising for Saturday afternoon/evening as that cold front moves south  across the country colliding with the very warm air. Showing thunderstorms forming as it reaches the midlands on ECM by 16:00 with winds appearing to converge possibly too. Can only hope that this becomes a reality  

[Allseasons-Si]

14 hours ago, Zak M said:

Still a bit uncertain about this but there is a chance of the odd lightning strike tomorrow as heavy showers from (I'm still learning so correct me if I'm wrong but it looks like an occluded front?) moving north. Some heavy showers could also form in NW France and might drift up north during Wednesday evening and night.

Here is CW's take on it so you are not far wrong.

----------------------------------------------------------------

Day 1 Convective Outlook

VALID 06:00 UTC Wed 06 May 2020 - 05:59 UTC Thu 07 May 2020

ISSUED 20:06 UTC Tue 05 May 2020

ISSUED BY: Dan

Upper ridge across the British Isles will slowly retreat to the Continent on Wednesday, allowing an upper low over the Atlantic to the west of Biscay to extend a trough towards Ireland/western Britain. The net result is a strengthening southerly flow, advecting a relatively high ThetaW airmass northwestwards from the Bay of Biscay across the Celtic Sea and towards Ireland. The combination of gradual warming of the profile at ~900mb combined with cooling of the mid-levels (500-700mb), most pronounced on Wednesday night as an upper trough axis swings northwards, will ultimately steepen mid-level lapse rates and increase mid-level instability. 

Several impulses will aid in the development of showery outbreaks of rain through Wednesday and Wednesday night, running from Cornwall / Isles of Scilly northwestwards towards southern Ireland. Initially instability will be fairly weak, and while a few isolated lightning strikes cannot be ruled out the risk in any one location is relatively low. However, with each passing hour, and as the main trough axis approaches, mid-level instability will gradually increase to 100-300 J/kg CAPE bringing an increasing risk of some sporadic lightning by the afternoon and evening hours - primarily over the open waters of the Celtic Sea, but also extending inland across parts of Ireland during the evening and night hours. Confidence is not particularly high in the exact coverage of lightning, but have tentatively introduced a low-end SLGT where lightning is considered most likely to occur, but a few isolated strikes may be possible elsewhere.

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.

Estofex

http://www.estofex.org/

[Kirkcaldy Weather]

Small chance for Ireland and SW uk tomorrow with fronts and some CAPE developing. 

[Benny123]

30 minutes ago, Kirkcaldy Weather said:

Small chance for Ireland and SW uk tomorrow with fronts and some CAPE developing. 

Some shear aloft too. 

[Thunder and Lightning]

4 hours ago, Kirkcaldy Weather said:

Small chance for Ireland and SW uk tomorrow with fronts and some CAPE developing. 

Also some models are developing CAPE and also storms into C and S England as well...

[East_England_Stormchaser91]

A Possibly interesting little day tomorrow, particularly into the evening hours. A couple of hi res models show an outbreak of showers/storms over wales, west mids and into Cheshire heading E-NE as the evening progresses. The Euro 4 and WRF 2km even show some discrete cells lasting into the early hours of Friday into Lincs. Given some decent DLS around 40knts, the possibility is certainly there. 

[Zak M]

THUNDERSTORM OUTLOOK - THU 07 MAY 2020

Valid: Thursday 07 May 00z - Friday 08 May 00z

Some heavy showers capable of producing the odd lightning strike from the Celtic Sea will travel north up to Ireland and N. Ireland by the early hours of Thursday morning, associated with a couple of hundred j/kg CAPE. By midday some of the heavy showers will still linger over Ireland, with perhaps a few travelling up to Scotland. By the afternoon some showers will re-develop, mainly over N. Ireland, with perhaps a few developing in W Scotland, where 200-700j/kg CAPE will be present. A few sporadic lightning strikes may be possible in some of these showers. Some sharp showers may also form in the afternoon in south-west and central-southern England. Lightning probability in SW/CS England is a bit questionable but 200-500j/kg CAPE will be present, so the odd lightning strike certainly can't be ruled out, especially in the SW.

[ChezWeather]

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.

Edited May 6, 2020 by ChezWeather

[Allseasons-Si]

Day 2 Convective Outlook

VALID 06:00 UTC Thu 07 May 2020 - 05:59 UTC Fri 08 May 2020

ISSUED 21:28 UTC Wed 06 May 2020

ISSUED BY: Dan

Upper ridge will gradually retreat to the Continent, allowing the flow aloft to veer round to the southwest. This will advect a moisture plume of relatively high ThetaW, stretching from Ireland to SW England first thing on Thursday morning, northeastwards across the British Isles through the day. Initially, some modest elevated instability will be present, with subtle impulses aiding in the development of pulses of showery rain drifting N/NE-wards through the day. As a result, there will be a low (but non-zero) risk of isolated lightning, hence the broad LOW threat area.

Diurnal heating will yield 300-600 J/kg CAPE by late morning, and more especially into the afternoon. The slack surface pattern will encourage areas of low-level convergence to form, and these (in conjunction with orographic forcing) will provide the primary focus for lift in order to develop a few scattered showers. CAM guidance suggests surface-based convection may initiate around 12-1pm, particularly across parts of Ireland and SW England, with additional development then likely through the afternoon and evening hours in other parts of Ireland / England and Wales. Some sporadic lightning seems likely over parts of the Republic of Ireland into Northern Ireland (30-35% chance) during the afternoon and early evening where convection will be deepest (but dependent on sufficient cloud clearance), but is more questionable over England and Wales (20-25% chance) where instability will be somewhat lower and convection a little more restricted in depth - the risk over N Devon / Somerset considered just high enough to warrant a low-end SLGT (30%) if convection can fire early enough in the afternoon. In fact, forecast profiles suggest warming aloft may occur later in the day as a ridge axis develops and moves from southwest to northeast, reducing the window for lightning potential. We may consider extending the SLGT across parts of SE Wales / Gloucestershire / N Oxfordshire / S Warwickshire if confidence on lightning potential increases, given a pronounced convergence zone that may become established during the late afternoon / evening hours.

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.

[Allseasons-Si]

@ChezWeather

Posted the same time lol.

[Zak M]

3 minutes ago, Allseasons-si said:

 

That might be the smallest SLGT I have ever seen 

Edited May 6, 2020 by Zak M

[Allseasons-Si]

Just now, Zak M said:

That has to be the smallest SLGT I have ever seen 

Going to be massive then

[viking_smb]

it is quite small actually, so by the looks of things storms are going to fire from lundy island, interesting,

Edited May 6, 2020 by viking_smb

[staplehurst]

7 minutes ago, Zak M said:

That might be the smallest SLGT I have ever seen 

Certainly rivals this one! 

[Allseasons-Si]

10 minutes ago, Zak M said:

That might be the smallest SLGT I have ever seen 

 

9 minutes ago, Allseasons-si said:

Going to be massive then

I have done a bit of editing and i hope it turns out like this

[Paul Sherman]

BBC really getting on board with Saturday showing a rash of Showers on some of their forecasts now (Pretty sure they get their data from Meteogroup)

Whats your early thoughts on this Mr Holley ?

[staplehurst]

4 minutes ago, Paul Sherman said:

BBC really getting on board with Saturday showing a rash of Showers on some of their forecasts now (Pretty sure they get their data from Meteogroup)

Whats your early thoughts on this Mr Holley ?

They'll be using the EC to drive their graphics. Most models are in reasonable agreement for a scattering of showers and a few thunderstorms on Saturday afternoon / evening, particularly north of the M4 - but still a few days to iron out that detail. Might need to keep an eye on what comes out of northern France Saturday night too, but that will depend heavily on the upper pattern and how quickly the cold front moves south, so more confident on daytime showers and less confident on any weakening convection over the Channel before the northerly comes crashing in. 

[Allseasons-Si]

19 minutes ago, Paul Sherman said:

BBC really getting on board with Saturday showing a rash of Showers on some of their forecasts now (Pretty sure they get their data from Meteogroup)

Whats your early thoughts on this Mr Holley ?

Yes Paul,they have been pretty steadfast with it.

today v's yesterday.

Edited May 6, 2020 by Allseasons-si
spellcheck