Storms and Convective discussion - June 2023

[sheikhy]

Ecm once again keeps the storm risk further west!gives me 1mm of rain out to day 10!!!west mids into wales seems to be the area!!!ukv ever so slightly further east and gfs the furthest east!!!!!

[alexisj9]

10 minutes ago, sheikhy said:

Ecm once again keeps the storm risk further west!gives me 1mm of rain out to day 10!!!west mids into wales seems to be the area!!!ukv ever so slightly further east and gfs the furthest east!!!!!

Anything looking like turning up at  night in this spell, or is it just the insolation induced day time storms?

Edited June 9, 2023 by alexisj9

[Guest]

Some showers now quickly developing in South Lyme Bay, not electrified yet but probably not long. 

[Rush2019]

European Severe storms lab. have a lot of interest for the UK tomorrow, especially SW.  Cannot see anything yet from Estofex.

[Scuba steve]

Currently in Lincolnshire ( Woodhall Spa ) looking at the onshore  winds from the North Sea gusting potentially to 30 mph I can’t see anything happening here though I would imagine the convergence zones to my west could create  something interesting 

[sheikhy]

35 minutes ago, alexisj9 said:

Anything looking like turning up at  night in this spell, or is it just the insolation induced day time storms?

Watever storms do develop shall continue well into the evening in some areas!!!!

[Guest]

8 minutes ago, Rush2112 said:

European Severe storms lab. have a lot of interest for the UK tomorrow, especially SW.  Cannot see anything yet from Estofex.

What’s happening down in Tunisia and Algeria? 

[camturbo]

35 minutes ago, Alderc said:

Some showers now quickly developing in South Lyme Bay, not electrified yet but probably not long. 

Your right they have developed quickly wonder if they will spark up

[alexisj9]

13 minutes ago, sheikhy said:

Watever storms do develop shall continue well into the evening in some areas!!!!

Just wondering cause there's instability moving north here, well east in Dover.

[Rush2019]

10 minutes ago, Alderc said:

What’s happening down in Tunisia and Algeria? 

Colour coding I think for high probability of hail/large hail.

[alexisj9]

7 minutes ago, alexisj9 said:

Just wondering cause there's instability moving north here, well east in Dover.

Moving north west

[Row w]

2 hours ago, I remember Atlantic 252 said:

Too far east here I feel, could be a day of storms out to my west, could even see lightning to my west eccy/NW, or Telford SW 

Hopefully they might drift more your way too, good chance of them popping up anywhere near 

[Eagle Eye]

There are significant levels of low-level energy from a very bouyant surface layer unaffected by downwards mixing of dewpoints (benefits of an initially unopen sector). Given weak shearing they are likely to be pulse-type with the occasional long lived cell in areas of higher shear. Which is where we have put the moderate as an educated guess for where that could be when combined with CAPE and bouyancy values.

 

3CAPE in excess of 50 J/KG(what tends to be needed for severe thunderstorms but the weak shearing takes most of that below severe thunderstorm status) fairly widespread with localised 150 J/KG of 3CAPE. 3CAPE is the averaged out CAPE in the 0-3 KM layer of the atmosphere. Values as high as 150 J/KG are very rare for her UK and if it weren't for the capping in place we might have gone for a tentative high risk. The capping means that we have kept it to a low-mid end moderate risk.

 

The activity of thunderstorms could be rather high-end in places though due to that intense low-level energy. Along with that low LCL's in places and very tall EL's (12KM or slightly above in places) mean that there will be very large amounts of entrainment CAPE and tall cloud heights. So would be a very high end UK storm day however there is significant capping in places.

 

This means that generally isolated but very active thunderstorms are likely to form rather than something like big clusters. In areas of low capping, a few clusters could form of active storms but it's hard to pinpoint them exactly now. This is most likely to happen where our moderate risk is though.

 

The slow moving nature of these storms along with the high PWAT and quite a lot of moisture taken up means that significant surface flooding may occur in a few places. Most storms tend to not take up loads of that moisture available but a severe has been added because one our two could dump 30-40mm (an inch and a half) of rain in a few areas leading to surface flooding. 

 

There is some support for small hail given high 3CAPE and fairly substantial LLLR's but the shearing tends not to support it and the warm profiles are even up into the mid-Troposphere so the <0 CAPE is very small and limited. With such a small hail growth zone it isn't much of a worry even with the high 3CAPE but maybe a few 1cm hailstones may fall. 

 

The convective temperature needed to break the cap is likely to not be reached in the SE and London except for a few forcing mechanisms that can modify the air parcel or force the breaking of a non surface cap. This all occurs in-front of a decaying occluded front which sends out gravity waves ahead of it along with the rising moisture and energy. Meaning that cloud heights from these storms may be taller than CAM'S are currently forecast. Meaning thst they could send out gravity waves if they hit the troposphere and that means that there may be some forcing from gravity waves just enough to break the cap if the convective temperature is borderline further east. This may also happen if cloud cover is less than forecast and CAM'S (convective allowing models) tend to overcloud in my experience. So areas fron Surrey westwards may get some storms though more isolated than the main action whereas the CAM'S currently show them getting nothing. Kent may get a shower or two but generally should steer clear of the thunderstorms. A small further advection of moisture overnight into Kent might provide a few showers capable of a few strikes of lightning overnight on Saturday. That is generally true across the central south as well with the same secondary advection of moist air and a weakening on the capping may allow for a few elevated clusters of showers to drift into the south/southeast overnight but we've kept it at a low risk for now, will likely update tomorrow in case the risk area or strength has changed. Its something for us to keep an eye on.

The convective temperature is reached on pretty much every single model easily where we've places the moderate but it's certainly a bust mode that is possible. Along with that, the elevated showers and storms in the SW/SW Wales and southern Ireland overnight on Friday may leave more cloud than currently forecast to break through which may decrease thunderstorm potential for the Wales area especially on Saturday but it shouldn't be too much because of the pure amount of energy and moisture in the area that would be able to build up with any little cloud break.

 

A severe has been added for quite a wide area for the possibility of localised significant flooding but quite a few areas will miss out on any storms at all because of the capping in place but areas thst do get them could get significant thunderstorms. Slow-moving and torrential rainfall in the strongest thunderstorms but its hard to pinpoint any areas at the moment other than a general area.

[Scuba steve]

2 minutes ago, Eagle Eye said:

There are significant levels of low-level energy from a very bouyant surface layer unaffected by downwards mixing of dewpoints (benefits of an initially unopen sector). Given weak shearing they are likely to be pulse-type with the occasional long lived cell in areas of higher shear. Which is where we have put the moderate as an educated guess for where that could be when combined with CAPE and bouyancy values.

 

3CAPE in excess of 50 J/KG(what tends to be needed for severe thunderstorms but the weak shearing takes most of that below severe thunderstorm status) fairly widespread with localised 150 J/KG of 3CAPE. 3CAPE is the averaged out CAPE in the 0-3 KM layer of the atmosphere. Values as high as 150 J/KG are very rare for her UK and if it weren't for the capping in place we might have gone for a tentative high risk. The capping means that we have kept it to a low-mid end moderate risk.

 

The activity of thunderstorms could be rather high-end in places though due to that intense low-level energy. Along with that low LCL's in places and very tall EL's (12KM or slightly above in places) mean that there will be very large amounts of entrainment CAPE and tall cloud heights. So would be a very high end UK storm day however there is significant capping in places.

 

This means that generally isolated but very active thunderstorms are likely to form rather than something like big clusters. In areas of low capping, a few clusters could form of active storms but it's hard to pinpoint them exactly now. This is most likely to happen where our moderate risk is though.

 

The slow moving nature of these storms along with the high PWAT and quite a lot of moisture taken up means that significant surface flooding may occur in a few places. Most storms tend to not take up loads of that moisture available but a severe has been added because one our two could dump 30-40mm (an inch and a half) of rain in a few areas leading to surface flooding. 

 

There is some support for small hail given high 3CAPE and fairly substantial LLLR's but the shearing tends not to support it and the warm profiles are even up into the mid-Troposphere so the <0 CAPE is very small and limited. With such a small hail growth zone it isn't much of a worry even with the high 3CAPE but maybe a few 1cm hailstones may fall. 

 

The convective temperature needed to break the cap is likely to not be reached in the SE and London except for a few forcing mechanisms that can modify the air parcel or force the breaking of a non surface cap. This all occurs in-front of a decaying occluded front which sends out gravity waves ahead of it along with the rising moisture and energy. Meaning that cloud heights from these storms may be taller than CAM'S are currently forecast. Meaning thst they could send out gravity waves if they hit the troposphere and that means that there may be some forcing from gravity waves just enough to break the cap if the convective temperature is borderline further east. This may also happen if cloud cover is less than forecast and CAM'S (convective allowing models) tend to overcloud in my experience. So areas fron Surrey westwards may get some storms though more isolated than the main action whereas the CAM'S currently show them getting nothing. Kent may get a shower or two but generally should steer clear of the thunderstorms. A small further advection of moisture overnight into Kent might provide a few showers capable of a few strikes of lightning overnight on Saturday. That is generally true across the central south as well with the same secondary advection of moist air and a weakening on the capping may allow for a few elevated clusters of showers to drift into the south/southeast overnight but we've kept it at a low risk for now, will likely update tomorrow in case the risk area or strength has changed. Its something for us to keep an eye on.

The convective temperature is reached on pretty much every single model easily where we've places the moderate but it's certainly a bust mode that is possible. Along with that, the elevated showers and storms in the SW/SW Wales and southern Ireland overnight on Friday may leave more cloud than currently forecast to break through which may decrease thunderstorm potential for the Wales area especially on Saturday but it shouldn't be too much because of the pure amount of energy and moisture in the area that would be able to build up with any little cloud break.

 

A severe has been added for quite a wide area for the possibility of localised significant flooding but quite a few areas will miss out on any storms at all because of the capping in place but areas thst do get them could get significant thunderstorms. Slow-moving and torrential rainfall in the strongest thunderstorms but its hard to pinpoint any areas at the moment other than a general area.

Can’t believe I’m in Lincolnshire normally U.K. tornado alley when the north west is going to get hammered

[sheikhy]

Latest ukv breaks out storms over the wash area around 1pm before moving west!!!thats waay further east!!!sunday not as stormy on this run for midlands area!!!!hot on both days widely!!!

[Harry]

First proper summery evening of the year! Windows and doors open, t-Rex sized mosquitoes and stag beetles all out and about - finally!! 
 

Summer 2023 is finally underway!! Looking forward to some pucker storm videos from some of you lucky folks

[sheikhy]

Gfs 18 now breaks out storms further east aswell and earlier around 12pm!!!sunday looking stormy too!!!

[Eagle Eye]

Specifically for me, I've got two possibilities tomorrow that are both marginal events.

A marginally strong thunderstorm is possibly probably to may northeast early afternoon, note that the shortwave is further east than forecast, bringing me into the game a bit more. It's an alright sounding but if I can get a stronger parcel low-level temperature that's when it gets interesting.

Overnight and the strong Theta-W may allow elevated showers to form near me with a few embedded lightning strikes if all goes well. It'd be great if that could happen as it would be easier to get the lightning on camera just gotta keep the cameras rolling. With 2 now and maybe my phone, I've got a decent chance of capturing any lightning with a small storm in the distance zoomed in, don't mind if it's not a big wide one because it's easier to miss something with those. Love those storms when they're forecastable easier and I'm more ready but rarely is anything perfect. That's very unlikely to happen tomorrow night though.

P.S

The latest AROME has significantly increased the forcing for a large clustering/MCS and it would mean our moderate risk would almost be perfect just a few modifications to the southern part of it.

Oh and it wasn't going to miss anything about for you south coasters either.

  

I think this might slowly become a trend. We've seen it a few times before, I think we see the models downgrade slightly before the event but a few hours before re-correct themselves. This could have the potentially to be the biggest event of the year and once again put this year right up there since 2010 despite the month it had off.

 

Edited June 9, 2023 by Eagle Eye

[Cheshire Freeze]

28 minutes ago, Eagle Eye said:

Specifically for me, I've got two possibilities tomorrow that are both marginal events.

A marginally strong thunderstorm is possibly probably to may northeast early afternoon, note that the shortwave is further east than forecast, bringing me into the game a bit more. It's an alright sounding but if I can get a stronger parcel low-level temperature that's when it gets interesting.

Overnight and the strong Theta-W may allow elevated showers to form near me with a few embedded lightning strikes if all goes well. It'd be great if that could happen as it would be easier to get the lightning on camera just gotta keep the cameras rolling. With 2 now and maybe my phone, I've got a decent chance of capturing any lightning with a small storm in the distance zoomed in, don't mind if it's not a big wide one because it's easier to miss something with those. Love those storms when they're forecastable easier and I'm more ready but rarely is anything perfect. That's very unlikely to happen tomorrow night though.

P.S

The latest AROME has significantly increased the forcing for a large clustering/MCS and it would mean our moderate risk would almost be perfect just a few modifications to the southern part of it.

Oh and it wasn't going to miss anything about for you south coasters either.

  

I think this might slowly become a trend. We've seen it a few times before, I think we see the models downgrade slightly before the event but a few hours before re-correct themselves. This could have the potentially to be the biggest event of the year and once again put this year right up there since 2010 despite the month it had off.

 

That looks really quite severe heading up through Wales, West Midlands into NW England.

I’ve looked at the accumulated totals and there are isolated spot totals of 80mm with 30-50mm more common widely.

Possibly one of those where the most severe weather is found on the eastern edge of the system…where there’s an overlap of factors between highest temperatures, CAPE and forcing.

Edited June 9, 2023 by CreweCold

[Harry]

First Ac of the year - boom!

Edit - should probably clarify, that is not me saying I’m expecting storms to erupt lol - it’s more of a Basil brush ‘boom boom’

Edited June 10, 2023 by Harry

[JR319]

Wishful thinking but I do hope it edges slightly more to the east so that us in the East Midlands can join in on the action too

[Tamsin]

3 hours ago, Harry said:

First proper summery evening of the year! Windows and doors open, t-Rex sized mosquitoes and stag beetles all out and about - finally!! 
 

Summer 2023 is finally underway!! Looking forward to some pucker storm videos from some of you lucky folks

Summer definitely happened today

[Harry]

Much more Ac now - moisture laden air incoming slowly but surely 

Edited June 10, 2023 by Harry

[Mapantz]

A few bits here as well..

[matty40s]

Just starting to build in Northants.