Storms and Convective discussion- 7th August onwards

[sparky1972]

Good morning all, well going by the forecast this years membership to the no storms club has been extended to the summer 2021 lol. 

[Kiwi]

42 minutes ago, Richard Taylor said:

The works! Biblical rain, shotgun thunder, freq lightning. 

Biblical rain? ....figures..it is 2020 after all.

Wonder what today will bring? Any chance of tornadoes and waterspouts or perhaps a plague of locusts?

[Harry]

The severe weather Europe forecast is tragic for the SE and the COS. Pretty much the same areas again!

Chances do seem higher though today and Nick F forecast is more encouraging. Although while I haven’t the time today to do too much chart searching the MCS referred to in Nick F forecast, according to the NetWx model, seems likely to be a Kent clipper/Benelux affair.

[Weather-history]

Matt Hugo gives SE England some hope

 

[Mitch the motorbike storm]

2 minutes ago, Harry said:

The severe weather Europe forecast is tragic for the SE and the COS. Pretty much the same areas again!

Chances do seem higher though today and Nick F forecast is more encouraging. Although while I haven’t the time today to do too much chart searching the MCS referred to in Nick F forecast, according to the NetWx model, seems likely to be a Kent clipper/Benelux affair.

I give up 

 

[JoeShmoe]

17 minutes ago, Craigers said:

Parts near Edinburgh have had torrential rain and thunder and lightning for nearly 10hours straight! Now that is EXTREME.

Certainly the most extreme storm I’ve ever seen in terms of length and intensity. Videos on Facebook doing the rounds of houses being struck in Edinburgh and flash flooding all over. It’s really warm and humid here now too 

[Norfolk Sheep]

1 minute ago, Mitch perrott said:

I give up 

 

At least you've got a coloured bit. Look at poor East Anglia 

[oliverek7]

6 minutes ago, Harry said:

The severe weather Europe forecast is tragic for the SE and the COS. Pretty much the same areas again!

Chances do seem higher though today and Nick F forecast is more encouraging. Although while I haven’t the time today to do too much chart searching the MCS referred to in Nick F forecast, according to the NetWx model, seems likely to be a Kent clipper/Benelux affair.

Might as well just put a 100% severe storm risk on Birmingham and the like today. What’s the point of even speculating the risk there and where the storms will be

Edited August 12, 2020 by Oliver Wyndham-lewis

[Flash bang flash bang etc]

5 minutes ago, Harry said:

The severe weather Europe forecast is tragic for the SE and the COS. Pretty much the same areas again!

Chances do seem higher though today and Nick F forecast is more encouraging. Although while I haven’t the time today to do too much chart searching the MCS referred to in Nick F forecast, according to the NetWx model, seems likely to be a Kent clipper/Benelux affair.

There’s a shortwave due to destabilise the airmass over the CS into the night tonight. I’ve not seen a chance like this for our area for ages. Just wait and see what happens

[Mitch the motorbike storm]

2 minutes ago, Norfolk Sheep said:

At least you've got a coloured bit. Look at poor East Anglia 

We both give up then 

[Gordon Webb]

Day 1 Convective Outlook

VALID 06:00 UTC Wed 12 Aug 2020 - 05:59 UTC Thu 13 Aug 2020

ISSUED 07:05 UTC Wed 12 Aug 2020

ISSUED BY: Dan

... SUMMARY ...

Elevated thunderstorms ongoing across NE Scotland and the Northern Isles during Wednesday morning

Aside from isolated elevated thunderstorms, scattered surface-based thunderstorms will develop in parts of England, Wales and Scotland from mid-afternoon, primarily near high ground and convergence boundaries

Thunderstorms will become increasingly numerous through the evening hours, merging into a complex from the Midlands into Wales

Large hail, damaging winds and flash flooding are all possible where storms occur

Other thunderstorms over France may push into S / SE England overnight, but confidence is low

There could be a relative minima in activity across some southern coastal counties, but have retained the SLGT for the overnight risk

... DISCUSSION ...

A marked shortwave will be driving a cluster of elevated thunderstorms across NE Scotland first thing on Wednesday morning, this will continue to lift northwards across Orkney and perhaps Shetland with time. Elsewhere, a few isolated elevated showers/weak thunderstorms may be possible across parts of England and Wales, especially the Midlands / SW England, driven by weak forcing aloft and rooted above a marked elevated mixed layer (EML). This EML will act as a cap, as strong surface heating through the day builds significant CAPE in the order of 1,000-2,500 J/kg - values rarely seen in the UK. In fact a climatology of UK CAPE 2002-2012 suggests the highest observed in this period was locally >3,000 J/kg during the heatwave of August 2003, once again noting how remarkable this current heatwave is.

 

Forecast soundings suggest temperatures in the low 30s Celsius will be necessary to break through the cap, and so true surface-based convection seems unlikely until early/mid afternoon at the earliest; however, a few elevated thunderstorms will be possible during the morning, which may subsequently become rooted within the boundary layer during the afternoon. Convergence zones and topography will be key for initial initiation of surface-based convection, and so high ground of SW Scotland, Cumbria, Pennines, North York Moors, Cambrian mountains and low-level convergence zones along the M4/M40 corridors for example will be the key areas. Once convection manages to break through the cap, explosive development is expected with cloud tops to 40,000ft (ELTs -55C). Shear is a little meagre, 10-15kts, and so likely to lead to downbursts and cold pools, which in turn will lead to daughter cells developing nearby. Damaging gusts of up to 50-60mph will be possible associated with downbursts, and the magnitude of CAPE and mid-level lapse rates suggests large hail 3-4cm, locally 5cm, in diameter is possible. 

 

During the evening, a shortwave will approach from France into southern England, and this may also aid in eroding the cap and allowing numerous thunderstorms to develop near convergence boundaries / topographic forcing / outflow boundaries. 700mb steering flow would suggest storm motion will be 10-15mph to the NW initially, turning increasingly to the WNW and 20-25mph as the evening progresses and the flow aloft backs and strengthens. Thunderstorms may grow upscale into a larger complex as they track westwards across Wales during the evening, and out across the southern Irish Sea / Celtic Sea while lightning activity will probably weaken as it moves into E / SE Ireland.

 

During the evening hours, a band or cluster of thunderstorms over northern France will begin to drift north across the English Channel, potentially affecting the Channel Islands for a time - it is unclear where these storms will survive the crossing, but the vast majority of model guidance is in agreement that they will decay fairly rapidly after leaving the coast, with lightning activity tending to hug the French coastline to the east. Nonetheless, a few elevated thunderstorms may be possible across S / SE England overnight, and perhaps at the end of the night close to the East Anglia coast.

 

edit - just outside moderate and direction of storms does not favor me either but for those Birmingham westwards again look like getting clobbered especially as motion turns more W during evening

Edited August 12, 2020 by Gordon Webb

[oliverek7]

2 minutes ago, Gordon Webb said:

Day 1 Convective Outlook

VALID 06:00 UTC Wed 12 Aug 2020 - 05:59 UTC Thu 13 Aug 2020

ISSUED 07:05 UTC Wed 12 Aug 2020

ISSUED BY: Dan

... SUMMARY ...

Elevated thunderstorms ongoing across NE Scotland and the Northern Isles during Wednesday morning

Aside from isolated elevated thunderstorms, scattered surface-based thunderstorms will develop in parts of England, Wales and Scotland from mid-afternoon, primarily near high ground and convergence boundaries

Thunderstorms will become increasingly numerous through the evening hours, merging into a complex from the Midlands into Wales

Large hail, damaging winds and flash flooding are all possible where storms occur

Other thunderstorms over France may push into S / SE England overnight, but confidence is low

There could be a relative minima in activity across some southern coastal counties, but have retained the SLGT for the overnight risk

... DISCUSSION ...

A marked shortwave will be driving a cluster of elevated thunderstorms across NE Scotland first thing on Wednesday morning, this will continue to lift northwards across Orkney and perhaps Shetland with time. Elsewhere, a few isolated elevated showers/weak thunderstorms may be possible across parts of England and Wales, especially the Midlands / SW England, driven by weak forcing aloft and rooted above a marked elevated mixed layer (EML). This EML will act as a cap, as strong surface heating through the day builds significant CAPE in the order of 1,000-2,500 J/kg - values rarely seen in the UK. In fact a climatology of UK CAPE 2002-2012 suggests the highest observed in this period was locally >3,000 J/kg during the heatwave of August 2003, once again noting how remarkable this current heatwave is.

 

Forecast soundings suggest temperatures in the low 30s Celsius will be necessary to break through the cap, and so true surface-based convection seems unlikely until early/mid afternoon at the earliest; however, a few elevated thunderstorms will be possible during the morning, which may subsequently become rooted within the boundary layer during the afternoon. Convergence zones and topography will be key for initial initiation of surface-based convection, and so high ground of SW Scotland, Cumbria, Pennines, North York Moors, Cambrian mountains and low-level convergence zones along the M4/M40 corridors for example will be the key areas. Once convection manages to break through the cap, explosive development is expected with cloud tops to 40,000ft (ELTs -55C). Shear is a little meagre, 10-15kts, and so likely to lead to downbursts and cold pools, which in turn will lead to daughter cells developing nearby. Damaging gusts of up to 50-60mph will be possible associated with downbursts, and the magnitude of CAPE and mid-level lapse rates suggests large hail 3-4cm, locally 5cm, in diameter is possible. 

 

During the evening, a shortwave will approach from France into southern England, and this may also aid in eroding the cap and allowing numerous thunderstorms to develop near convergence boundaries / topographic forcing / outflow boundaries. 700mb steering flow would suggest storm motion will be 10-15mph to the NW initially, turning increasingly to the WNW and 20-25mph as the evening progresses and the flow aloft backs and strengthens. Thunderstorms may grow upscale into a larger complex as they track westwards across Wales during the evening, and out across the southern Irish Sea / Celtic Sea while lightning activity will probably weaken as it moves into E / SE Ireland.

 

During the evening hours, a band or cluster of thunderstorms over northern France will begin to drift north across the English Channel, potentially affecting the Channel Islands for a time - it is unclear where these storms will survive the crossing, but the vast majority of model guidance is in agreement that they will decay fairly rapidly after leaving the coast, with lightning activity tending to hug the French coastline to the east. Nonetheless, a few elevated thunderstorms may be possible across S / SE England overnight, and perhaps at the end of the night close to the East Anglia coast.

 

Not sounding impressive at all for the SE then  

[Aiden2012]

what's the chance of these getting to me

[Calayte]

I cannot get over that light show last night, that has to have been one of the best i have seen in years. I have some pictures in this thread is anyone's interested.

[Azazel]

Yikes - Midlands north again it is then. This must be one of the best convective seasons of all time up that way and into the North West!

[Mitch the motorbike storm]

6 minutes ago, Gordon Webb said:

Day 1 Convective Outlook

VALID 06:00 UTC Wed 12 Aug 2020 - 05:59 UTC Thu 13 Aug 2020

ISSUED 07:05 UTC Wed 12 Aug 2020

ISSUED BY: Dan

... SUMMARY ...

Elevated thunderstorms ongoing across NE Scotland and the Northern Isles during Wednesday morning

Aside from isolated elevated thunderstorms, scattered surface-based thunderstorms will develop in parts of England, Wales and Scotland from mid-afternoon, primarily near high ground and convergence boundaries

Thunderstorms will become increasingly numerous through the evening hours, merging into a complex from the Midlands into Wales

Large hail, damaging winds and flash flooding are all possible where storms occur

Other thunderstorms over France may push into S / SE England overnight, but confidence is low

There could be a relative minima in activity across some southern coastal counties, but have retained the SLGT for the overnight risk

... DISCUSSION ...

A marked shortwave will be driving a cluster of elevated thunderstorms across NE Scotland first thing on Wednesday morning, this will continue to lift northwards across Orkney and perhaps Shetland with time. Elsewhere, a few isolated elevated showers/weak thunderstorms may be possible across parts of England and Wales, especially the Midlands / SW England, driven by weak forcing aloft and rooted above a marked elevated mixed layer (EML). This EML will act as a cap, as strong surface heating through the day builds significant CAPE in the order of 1,000-2,500 J/kg - values rarely seen in the UK. In fact a climatology of UK CAPE 2002-2012 suggests the highest observed in this period was locally >3,000 J/kg during the heatwave of August 2003, once again noting how remarkable this current heatwave is.

 

Forecast soundings suggest temperatures in the low 30s Celsius will be necessary to break through the cap, and so true surface-based convection seems unlikely until early/mid afternoon at the earliest; however, a few elevated thunderstorms will be possible during the morning, which may subsequently become rooted within the boundary layer during the afternoon. Convergence zones and topography will be key for initial initiation of surface-based convection, and so high ground of SW Scotland, Cumbria, Pennines, North York Moors, Cambrian mountains and low-level convergence zones along the M4/M40 corridors for example will be the key areas. Once convection manages to break through the cap, explosive development is expected with cloud tops to 40,000ft (ELTs -55C). Shear is a little meagre, 10-15kts, and so likely to lead to downbursts and cold pools, which in turn will lead to daughter cells developing nearby. Damaging gusts of up to 50-60mph will be possible associated with downbursts, and the magnitude of CAPE and mid-level lapse rates suggests large hail 3-4cm, locally 5cm, in diameter is possible. 

 

During the evening, a shortwave will approach from France into southern England, and this may also aid in eroding the cap and allowing numerous thunderstorms to develop near convergence boundaries / topographic forcing / outflow boundaries. 700mb steering flow would suggest storm motion will be 10-15mph to the NW initially, turning increasingly to the WNW and 20-25mph as the evening progresses and the flow aloft backs and strengthens. Thunderstorms may grow upscale into a larger complex as they track westwards across Wales during the evening, and out across the southern Irish Sea / Celtic Sea while lightning activity will probably weaken as it moves into E / SE Ireland.

 

During the evening hours, a band or cluster of thunderstorms over northern France will begin to drift north across the English Channel, potentially affecting the Channel Islands for a time - it is unclear where these storms will survive the crossing, but the vast majority of model guidance is in agreement that they will decay fairly rapidly after leaving the coast, with lightning activity tending to hug the French coastline to the east. Nonetheless, a few elevated thunderstorms may be possible across S / SE England overnight, and perhaps at the end of the night close to the East Anglia coast.

 

Incoming drizzle for South east then

[SalopWatcher]

On for the hatrick today then... the forecasts look great for Shropshire up to the north west again. Though how anything can top last night I don’t know! 

[James1979]

15 minutes ago, Norfolk Sheep said:

At least you've got a coloured bit. Look at poor East Anglia 

How things have changed, the old UK climate has shifted North and we are stuck in a semi desert here. Had a few rumbles Monday but no lighting or even rain and seen some lovely distant CBs but nothing from them and looks like the horrific heat will fizzle out with a whimper again in SE with time running out. Zzzzz.

[Chris.R]

Looking good here for later. A bit disappointed I missed out yesterday but  Hopefully today and tomorrow will make up for it.

[Mitch the motorbike storm]

Nope I don't care anymore! Getting on my motorbike today and chasing!

[seabreeze86]

5 minutes ago, Azazel said:

Yikes - Midlands north again it is then. This must be one of the best convective seasons of all time up that way and into the North West!

Not everywhere in the north we have had nothing here not really been hot either, struggling to break 20c with all the cloud around over the next few days 

[oliverek7]

4 minutes ago, James1979 said:

How things have changed, the old UK climate has shifted North and we are stuck in a semi desert here. Had a few rumbles Monday but no lighting or even rain and seen some lovely distant CBs but nothing from them and looks like the horrific heat will fizzle out with a whimper again in SE with time running out. Zzzzz.

What is it with this year?? this could be the worst year I’ve ever seen for storms here in the southeast. The best storm I’ve seen all year was the squall line that went right through London in early June from the north and that was with temperatures at only 14C yet during a mega heatwave we get nothing. Stupid cap!

Edited August 12, 2020 by Oliver Wyndham-lewis

[Norfolk Sheep]

3 minutes ago, James1979 said:

How things have changed, the old UK climate has shifted North and we are stuck in a semi desert here. Had a few rumbles Monday but no lighting or even rain and seen some lovely distant CBs but nothing from them and looks like the horrific heat will fizzle out with a whimper again in SE with time running out. Zzzzz.

I for one will be staying well away from the radar and any comments raving about insane storms. I've had enough.

[Azazel]

Just now, seabreeze86 said:

Not everywhere in the north we have had nothing here not really been hot either, struggling to break 20c with all the cloud around over the next few days 

Yes the north east looks dire - no heat and no storms. At least we got the heat down here, but my goodness me I could do with some cooling rain about now.

[seabreeze86]

1 minute ago, Azazel said:

Yes the north east looks dire - no heat and no storms. At least we got the heat down here, but my goodness me I could do with some cooling rain about now.

Yeah it’s been a case of what heatwave up here although there have been some pleasant days so not all bad. All the Cape around the country today and look at what is forecast here