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Storms and convective discussion - 18th June 2020 onwards


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This was the late evening storm as it passed over Filey. It was nice enough as it come up from Bridlington, but as it approached the coast, a real nice feeder band developed into it and it really ramp

My view of the Bude cell   Edit:excuse the washing

Very impressive lightning display here in Scotland in the early hours. I am just a amateur photographer but I am pleased with what I managed to capture. Here is a selection of all the best ones I got.

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21 minutes ago, Mapantz said:

Doesn't seem to match the UKV

viewimage.thumb.png.4dba434a6b2fa7f2d6cc82749fc44abc.png

There's conformation and it's on the 21z 😄

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The UKV has done a full circle as far as storms IMBY is concerned. At the start of the day the nearest area storms were showing on there was around 100 miles away, later on it showed storms overhead and now its back to showing them 100 miles away again now. 

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6 hours ago, matt111 said:

The UKV has done a full circle as far as storms IMBY is concerned. At the start of the day the nearest area storms were showing on there was around 100 miles away, later on it showed storms overhead and now its back to showing them 100 miles away again now. 

Yep, exactly what it did a month ago. It's just not even worth looking at the day before these 'events'. It now keeps all storms in the North Sea

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Convective weather has slight for the eastern england and south east.

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Risk Map Shifted slightly further W into Eastern England/Kent

image.thumb.png.3a6817d54441ffc1233c073bef302c54.png

Day 1 Convective Outlook

VALID 06:00 UTC Fri 31 Jul 2020 - 05:59 UTC Sat 01 Aug 2020

ISSUED 07:12 UTC Fri 31 Jul 2020

ISSUED BY: Dan

Upper ridge over eastern Britain will amplify further as it drifts eastwards across the North Sea and substantial warm advection occurs. Meanwhile, a relaxing upper longwave trough will approach from the Atlantic, the net result drawing a hot, dry airmass northwards across western Europe in the broad southerly flow aloft. 

Two tongues of high Theta-W will be advected northwards through Friday - one across Ireland immediately ahead of the cold front, and a second more widely across England into eastern Scotland. These two plumes will ultimately merge into one by the early hours of Saturday as they clear to the North Sea. Consequently, any minor impulses aloft could bring the risk of isolated elevated thunderstorms almost anywhere across the British Isles, hence a fairly large LOW threat level issued, but the risk in any one location is considered quite low. Areas with more interest are outlined below.

 

Forecast profiles suggest an uptick in embedded elevated convection is possible across central / eastern Ireland on Friday morning on the leading edge of the frontal rain associated with the cold front. This could bring the risk of some sporadic lightning, which would potentially migrate NNE-wards across Northern Ireland towards W / SW Scotland. If confidence improves, a SLGT may be introduced. The frontal rain is expected to weaken over Ireland towards midday and into the afternoon as the PVA lobe aloft overruns and moves into western Britain, ahead of the cold front. 

 

Meanwhile, a substantial EML will spread gradually northwards from the English Channel across much of England and east Wales to reach the Scottish borders by early evening. This will serve as a cap, preventing any surface-based convection from occurring - forecast profiles suggest surface temperatures of 38C or higher would be required, and given the lack of any substantial trigger and very dry profiles, this seems rather unlikely. However, a shortwave will drift northeastwards from the English Channel 12z to East Anglia by 18z, and this will aid in cooling and some moistening of the 550-650mb layer. Consequently, an increase in elevated convective cloud (AcCas at 10-12,000ft!) is likely to spread into south and southeast England during the afternoon, perhaps as far west as east Devon / SE Wales / NW England. The subtle forcing aloft may just be sufficient for this convection to grow deep enough almost anywhere in England / SE Wales to produce a few sporadic lightning strikes - but is probably most likely towards S / SE England into the S + E Midlands / East Anglia, especially towards mid/late afternoon onwards where the subtle shortwave is slightly more pronounced. Naturally there is some considerable uncertainty as to how widespread such activity may be, and the timing of initiation (if any). Worth noting that 00z runs of most models have markedly reduced the signal for thunderstorms, with the main area where agreement is best being Yorkshire. Very dry and hot air below the cloud base will likely cause most precipitation to evaporate before reaching the ground, at least initially.

 

The shortwave is expected to become more pronounced with each passing hour through the evening hours as it continues to migrate NE-wards across east and southeast England, and consequently there could be an increasing risk of elevated showers and thunderstorms developing during this time over these areas. As such, a SLGT has been introduced, but this may be expanded southwestwards to include other parts of the south Midlands / SE England depending on how quickly destabilisation may occur. While precipitation at the ground may be somewhat limited, lightning activity could become quite frequent in the most intense cells. Inverted-V profiles suggest some gusty winds and heat bursts will be possible. Any elevated showers/thunderstorms will generally clear to the North Sea by 00z (while probably continuing to expand in coverage as they move offshore).

At the same time, the PVA lobe associated with the approaching Atlantic upper trough will begin to engage with the northern portions of the instability plume, by the evening hours over parts of central / southern / eastern Scotland, and this may also result in an increase in elevated shower/thunderstorm development, primarily over the northern North Sea but perhaps also into parts of NE Scotland and the Northern Isles later in the night.

 

The remnants of the first Theta-W tongue immediately ahead of the cold front could still produce the odd isolated lightning strike elsewhere in England and Wales as this continues to track eastwards through Friday night.

Edited by Jamiee
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Looks like ECM was bang on the money as far back as Sunday, when it downgraded the storm potential massively.

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image.thumb.png.141827cce4baf5fcc781cc3f698ad6dc.png

Yellow thunderstorm warning.

Along with some very hot weather today, a few thunderstorms are likely to break out during the late afternoon and evening. Where thunderstorms do occur frequent lightning is expected, along with gusty winds. Unlike many days with thunderstorms over the UK, relatively little in the way of heavy rain is expected. However, a few places may be unlucky and catch a heavy downpour, perhaps even with some hail, and as much as 15-20 mm rain could fall in less than an hour, most likely in Eastern England.

image.thumb.png.f98c80f24ceaa6c90bc87c8f24dbb531.png

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Patches of (presumably) AcCas now above and to the south of the the Channel Islands on satellite. Look out for these beauties filling the skies across southern and central areas a little later today.

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Just now, Lance M said:

Patches of (presumably) AcCas now above and to the south of the the Channel Islands on satellite. Look out for these beauties filling the skies across southern and central areas a little later today.

It’s just a tease as we likely to see little or no electrical activity later anyway - but gotta love an acas-filled Sky 🙂

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3 minutes ago, Flash bang flash bang etc said:

It’s just a tease as we likely to see little or no electrical activity later anyway - but gotta love an acas-filled Sky 🙂

Yeah, absolutely. Other than CBs, they're my favourite clouds, so I love to see them, storms or no storms. If they do start sparking (I mean in general, not today), then all the better 😄 

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50 minutes ago, Jamiee said:

image.thumb.png.141827cce4baf5fcc781cc3f698ad6dc.png

Yellow thunderstorm warning.

Along with some very hot weather today, a few thunderstorms are likely to break out during the late afternoon and evening. Where thunderstorms do occur frequent lightning is expected, along with gusty winds. Unlike many days with thunderstorms over the UK, relatively little in the way of heavy rain is expected. However, a few places may be unlucky and catch a heavy downpour, perhaps even with some hail, and as much as 15-20 mm rain could fall in less than an hour, most likely in Eastern England.

image.thumb.png.f98c80f24ceaa6c90bc87c8f24dbb531.png

Has anyone thought, that may be ppn charts in advance do not show the full story. Chance of little to no rain with this lot, it is very dry air below the active area. This isn't even a radar watching event, it's a look out the window, and see what the sky looks like event. 

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Perhaps *some* scope for elevated convection later this afternoon but the risk of home grown storms today really is rather low, the atmosphere is just too capped.

446359343_Screenshot2020-07-31at10_38_44.thumb.png.dcccbf6cabd73cc39ba41cf6318bf57e.png

Our best bet is for storms building across France to move northwards but as this stand a huge majority of models send the storms east of the UK. 

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Day 1 Convective Outlook

VALID 06:00 UTC Fri 31 Jul 2020 - 05:59 UTC Sat 01 Aug 2020

ISSUED 09:38 UTC Fri 31 Jul 2020

ISSUED BY: Dan

UPDATE 09:38 UTC SLGT introduced to northern / eastern Ireland into SW Scotland (see text discussion below for more information)

 

Upper ridge over eastern Britain will amplify further as it drifts eastwards across the North Sea and substantial warm advection occurs. Meanwhile, a relaxing upper longwave trough will approach from the Atlantic, the net result drawing a hot, dry airmass northwards across western Europe in the broad southerly flow aloft. 

Two tongues of high Theta-W will be advected northwards through Friday - one across Ireland immediately ahead of the cold front, and a second more widely across England into eastern Scotland. These two plumes will ultimately merge into one by the early hours of Saturday as they clear to the North Sea. Consequently, any minor impulses aloft could bring the risk of isolated elevated thunderstorms almost anywhere across the British Isles, hence a fairly large LOW threat level issued, but the risk in any one location is considered quite low. Areas with more interest are outlined below.

 

Forecast profiles suggest an uptick in embedded elevated convection is possible across central / eastern Ireland on Friday morning on the leading edge of the frontal rain associated with the cold front. This could bring the risk of some sporadic lightning, which would potentially migrate NNE-wards across Northern Ireland towards W / SW Scotland. If confidence improves, a SLGT may be introduced. The frontal rain is expected to weaken over Ireland towards midday and into the afternoon as the PVA lobe aloft overruns and moves into western Britain, ahead of the cold front. 

 

Meanwhile, a substantial EML will spread gradually northwards from the English Channel across much of England and east Wales to reach the Scottish borders by early evening. This will serve as a cap, preventing any surface-based convection from occurring - forecast profiles suggest surface temperatures of 38C or higher would be required, and given the lack of any substantial trigger and very dry profiles, this seems rather unlikely. However, a shortwave will drift northeastwards from the English Channel 12z to East Anglia by 18z, and this will aid in cooling and some moistening of the 550-650mb layer. Consequently, an increase in elevated convective cloud (AcCas at 10-12,000ft!) is likely to spread into south and southeast England during the afternoon, perhaps as far west as east Devon / SE Wales / NW England. The subtle forcing aloft may just be sufficient for this convection to grow deep enough almost anywhere in England / SE Wales to produce a few sporadic lightning strikes - but is probably most likely towards S / SE England into the S + E Midlands / East Anglia, especially towards mid/late afternoon onwards where the subtle shortwave is slightly more pronounced. Naturally there is some considerable uncertainty as to how widespread such activity may be, and the timing of initiation (if any). Worth noting that 00z runs of most models have markedly reduced the signal for thunderstorms, with the main area where agreement is best being Yorkshire. Very dry and hot air below the cloud base will likely cause most precipitation to evaporate before reaching the ground, at least initially.

 

The shortwave is expected to become more pronounced with each passing hour through the evening hours as it continues to migrate NE-wards across east and southeast England, and consequently there could be an increasing risk of elevated showers and thunderstorms developing during this time over these areas. As such, a SLGT has been introduced, but this may be expanded southwestwards to include other parts of the south Midlands / SE England depending on how quickly destabilisation may occur. While precipitation at the ground may be somewhat limited, lightning activity could become quite frequent in the most intense cells. Inverted-V profiles suggest some gusty winds and heat bursts will be possible. Any elevated showers/thunderstorms will generally clear to the North Sea by 00z (while probably continuing to expand in coverage as they move offshore).

At the same time, the PVA lobe associated with the approaching Atlantic upper trough will begin to engage with the northern portions of the instability plume, by the evening hours over parts of central / southern / eastern Scotland, and this may also result in an increase in elevated shower/thunderstorm development, primarily over the northern North Sea but perhaps also into parts of NE Scotland and the Northern Isles later in the night.

 

The remnants of the first Theta-W tongue immediately ahead of the cold front could still produce the odd isolated lightning strike elsewhere in England and Wales as this continues to track eastwards through Friday night.

 

http://convectiveweather.co.uk/forecast.php?date=2020-07-31&fbclid=IwAR3hXbdkVK1_03-HkRMn6iP7cihNM8Zssz_oCbVj9sRn4fF021_FPaozBp4

 

largethumb.png

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34 minutes ago, Thunder and Lightning said:

Yikes, 37c on the latest UKV.

image.thumb.png.a368dea939241b40dc39e6a0e62cfdae.png

Plus it is now showing a few thunderstorms breaking out across the SE and E.

image.thumb.png.2c1f80611da25f97180beccf151b1d3f.png

image.thumb.png.8e446919e5858a2d872442bbea205130.png

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It is definitely going to be a wait and see situation!

It’s already 31C and climbing rapidly! 35C seems likely - will be interesting if higher is achieved 😅

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1st signs of instability pushing up from the south...I have a good feeling about this evening in East Anglia / South East at least....

6DD110BB-66D6-4D05-ACE7-867F84381D23.jpeg

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some small amounts of ac-cas here in cardiff as per dans forecast, so he was on the mark with this as usual, 

personally the action will be further east in east england.

 

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I keep feeling like this will be one of those ‘wow it started a lot further west’ scenarios later on. Temps seem to be likely to go over what was forecast and I think that’s going to significantly affect the southward and westward point of destabilisation.

just a hunch but there’s a lot of room for change in the forecast, it’s not set in stone 🤞

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Just now, Flash bang flash bang etc said:

I keep feeling like this will be one of those ‘wow it started a lot further west’ scenarios later on. Temps seem to be likely to go over what was forecast and I think that’s going to significantly affect the southward and westward point of destabilisation.

just a hunch but there’s a lot of room for change in the forecast, it’s not set in stone 🤞

Well its already going in france, and quite far east for most of us, but it's still early yet. 

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Already 33c here. Storms breaking out on the East Coast of Ireland.  Will they make it across the Irish sea before being inhibited by the cap?

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