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Convective / Storm Discussion Thread - 31st May 2017 onwards


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Posted
  • Location: Frome
  • Location: Frome

I'm really hoping to get a good storm here in Bristol today but the storm risk has shifted to tomorrow on Netweather's forecast. It was showing a 67% risk for today but now it's zero. The Met Office and others though seem convinced we may have something here a bit later today. Will be watching the skies whilst sat at my desk in work, mainly because I've left the windows and sunroof open on my car haha!

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Posted
  • Location: Rochester, Kent
  • Location: Rochester, Kent

u3764_17062012_2000.thumb.gif.0e7d6cfcbb3c25d57c2ca094e11d72d6.gif

Today's hotspot is Cambridge and surrounding areas - particularly an area from Cardiff, through Cambridge out to the North Sea.

Small convective potential (K=23) may lead to thunderstorms. Quite some energy is available (CAPE = 1314 J/Kg, Dp = 18.4) and with large instability (LI = -5)  strong surface heating and a front stuck and occluding across the Midlands should lead to conditions for thunderstorm formation. Organisation does not look likely (SREH=27)

Happy Hunting!

 

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Posted
  • Location: on a canal , probably near Northampton...
  • Weather Preferences: extremes n snow
  • Location: on a canal , probably near Northampton...
2 hours ago, Flash bang flash bang etc said:

Surely it would have drifted away to sea by now?

It's now got as far as the Norfolk coast, not being able to sleep gave me an hourly view of where it had moved to .

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Posted
  • Location: Marlow - Bucks/Berks Border
  • Weather Preferences: Spring, Autumn, Snow ..... not, I repeat, not heatwaves!!
  • Location: Marlow - Bucks/Berks Border
46 minutes ago, Nick L said:

No real improvement until at least the end of the week sadly. Wouldn't mind it if there was a chance of storms, but down here? Fat chance.

I feel your pain Nick! The amount of times I've seen imports heading straight for this area and then either divert or split around us is not funny. Same with the snow .......... Chilterns Storm and Snow shield :-(

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Posted
  • Location: Wellingborough, Northamptonshire
  • Location: Wellingborough, Northamptonshire

two rumbles of thunder, now its chucking it down. Not a proper storm but its nice to have something

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Posted
  • Location: Cheddington, Buckinghamshire
  • Weather Preferences: Winter: Cold & Snowy, Summer: Just not hot
  • Location: Cheddington, Buckinghamshire
2 minutes ago, > mark said:

I feel your pain Nick! The amount of times I've seen imports heading straight for this area and then either divert or split around us is not funny. Same with the snow .......... Chilterns Storm and Snow shield :-(

Yeah I've not even lived here for 3 years, but I've fast learned that it's a weather wasteland.

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Posted
  • Location: Harefield, North West London
  • Weather Preferences: Big storm!
  • Location: Harefield, North West London

Clouds cleared, suns out in Watford! Let's see where it goes... 

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Posted
  • Location: Bedfordshire 33m above mean sea level
  • Weather Preferences: Snowy and thundery.
  • Location: Bedfordshire 33m above mean sea level

I got some nice warnings. Cloud is melting away.  

I'm in the back outlined area. Lovely to see.

weather.png

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Posted
  • Location: Wellingborough, Northamptonshire
  • Location: Wellingborough, Northamptonshire
2 minutes ago, Dami said:

I got some nice warnings. Cloud is melting away.  

I'm in the back outlined area. Lovely to see.

weather.png

what i find best about this is i didn't expect anything today and already im one of just a few today to already experience something even though im out of the warning zones, currently under a torrential downpour still 

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Posted
  • Location: Worthing, West Sussex
  • Weather Preferences: Anything unusual
  • Location: Worthing, West Sussex

When all the cape goes to pot and only France gets storms 

 

giphy.gif

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Posted
  • Location: Cheddington, Buckinghamshire
  • Weather Preferences: Winter: Cold & Snowy, Summer: Just not hot
  • Location: Cheddington, Buckinghamshire
6 minutes ago, Dami said:

I got some nice warnings. Cloud is melting away.  

I'm in the back outlined area. Lovely to see.

weather.png

Someone will have to explain that map to me...Why is the severe area completely detached from the risk areas?

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Posted
  • Location: Bedfordshire 33m above mean sea level
  • Weather Preferences: Snowy and thundery.
  • Location: Bedfordshire 33m above mean sea level

oh don't spoil it nick. :closedeyes:

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Posted
  • Location: Cheddington, Buckinghamshire
  • Weather Preferences: Winter: Cold & Snowy, Summer: Just not hot
  • Location: Cheddington, Buckinghamshire
1 minute ago, Dami said:

oh don't spoil it nick. :closedeyes:

Not trying to, I'm genuinely baffled by it! I am also just about in that puzzling area...

Edited by Nick L
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Posted
  • Location: Harefield, North West London
  • Weather Preferences: Big storm!
  • Location: Harefield, North West London

Bahhhh just outside of it

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Posted
  • Location: Cheddington, Buckinghamshire
  • Weather Preferences: Winter: Cold & Snowy, Summer: Just not hot
  • Location: Cheddington, Buckinghamshire

Just found an explanation for the risk areas and I am still none the wiser...So that SVR is basically a slight slight risk area?

http://www.convectiveweather.co.uk/criteriakey.php

Can't say I'm a fan of this UK emulation of SPC forecasts at the best of times.

Edited by Nick L
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Posted
  • Location: Bedfordshire 33m above mean sea level
  • Weather Preferences: Snowy and thundery.
  • Location: Bedfordshire 33m above mean sea level

It says only if the cap breaks. So i'm thinking we are either gonna get nothing or it's going to be a biggie. 

I don't think i'm going to be lucky. Hubs surprised me with an iphone7 this morning. That's my luck for today.

estofex is having none of it.

The met says the party will happen tomorrow.

Edited by Dami
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Posted
  • Location: South Gloucestershire BS35
  • Weather Preferences: Severe weather enthusiast
  • Location: South Gloucestershire BS35
3 minutes ago, Nick L said:

Someone will have to explain that map to me...Why is the severe area completely detached from the risk areas?

To me I think it is demonstrating that whilst there is the severe risk area outlined by the black line, it is still within a low risk zone. The severe is catering for the very low chance of developments IF they were to occur in that area. However I am still of the view the cap will be difficult to break.

The accompanying forecast from Convective Weather for that map is below (I believe the bit in bold refers to the SVR outline).

http://www.convectiveweather.co.uk/forecast.php?date=2017-06-20

Day 1 Convective Outlook

VALID 06:00 UTC Tue 20 Jun 2017 - 05:59 UTC Wed 21 Jun 2017

ISSUED 20:02 UTC Mon 19 Jun 2017

ISSUED BY: Dan

... WALES / MIDLANDS / W COUNTRY / HOME COUNTIES ...

Day-on-day weakening of the ~650mb nose continues as heights aloft gradually fall, which combined with low-level convergence and strong surface heating (generating 1,000 - 2,000 Jkg-1 CAPE) will bring the risk of a few isolated heavy showers / thunderstorms very late Tuesday afternoon into the evening hours. Forecast profiles are once again quite dry, which will serve to inhibit deep convection, but should a strong cell develop then, given such instability and dry air aloft, there is scope for large hail 2.0-2.5cm in diameter and localised flash flooding as a result of slow storm motion and local accumulations of 30-40mm in a short space of time. As a result, a SVR has been issued for this, but it is easily possible that no thunderstorms develop and consequently no severe weather will occur etc.

 

... REPUBLIC OF IRELAND / NORTHERN IRELAND / IRISH SEA / SCOTLAND / N ENGLAND ...

On Tuesday night, an approaching Atlantic trough will advect the high WBPT airmass over southern England northwards across the Irish Sea to Northern Ireland. Increased forcing as upper trough approaches will likely destabilise the mid-levels, especially during the latter stages of the night. An increase in elevated thunderstorm potential seems likely during the early hours of Wednesday, particularly over the Irish Sea, moving into Cumbria and parts of SW Scotland. The risk also extends farther south towards west Wales and perhaps SW England by Wednesday morning, but with less forcing likely here and so greater uncertainty as to whether such (large) instability will be released. The exact areas at risk is still somewhat uncertain, and hence the forecast may need adjusting nearer the time as confidence improves - the SLGT, for example, may need extending across Northern Ireland.

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Posted
  • Location: Cheddington, Buckinghamshire
  • Weather Preferences: Winter: Cold & Snowy, Summer: Just not hot
  • Location: Cheddington, Buckinghamshire
Just now, Chris K said:

To me I think it is demonstrating that whilst there is the severe risk area outlined by the black line, it is still within a low risk zone. The severe is catering for the very low chance of developments IF they were to occur in that area. However I am still of the view the cap will be difficult to break.

The accompanying forecast from Convective Weather for that map is below (I believe the bit in bold refers to the SVR outline).

http://www.convectiveweather.co.uk/forecast.php?date=2017-06-20

Day 1 Convective Outlook

VALID 06:00 UTC Tue 20 Jun 2017 - 05:59 UTC Wed 21 Jun 2017

ISSUED 20:02 UTC Mon 19 Jun 2017

ISSUED BY: Dan

... WALES / MIDLANDS / W COUNTRY / HOME COUNTIES ...

Day-on-day weakening of the ~650mb nose continues as heights aloft gradually fall, which combined with low-level convergence and strong surface heating (generating 1,000 - 2,000 Jkg-1 CAPE) will bring the risk of a few isolated heavy showers / thunderstorms very late Tuesday afternoon into the evening hours. Forecast profiles are once again quite dry, which will serve to inhibit deep convection, but should a strong cell develop then, given such instability and dry air aloft, there is scope for large hail 2.0-2.5cm in diameter and localised flash flooding as a result of slow storm motion and local accumulations of 30-40mm in a short space of time. As a result, a SVR has been issued for this, but it is easily possible that no thunderstorms develop and consequently no severe weather will occur etc.

 

... REPUBLIC OF IRELAND / NORTHERN IRELAND / IRISH SEA / SCOTLAND / N ENGLAND ...

On Tuesday night, an approaching Atlantic trough will advect the high WBPT airmass over southern England northwards across the Irish Sea to Northern Ireland. Increased forcing as upper trough approaches will likely destabilise the mid-levels, especially during the latter stages of the night. An increase in elevated thunderstorm potential seems likely during the early hours of Wednesday, particularly over the Irish Sea, moving into Cumbria and parts of SW Scotland. The risk also extends farther south towards west Wales and perhaps SW England by Wednesday morning, but with less forcing likely here and so greater uncertainty as to whether such (large) instability will be released. The exact areas at risk is still somewhat uncertain, and hence the forecast may need adjusting nearer the time as confidence improves - the SLGT, for example, may need extending across Northern Ireland.

Ok that makes a bit more sense, cheers.

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Posted
  • Location: Near Hull
  • Weather Preferences: Severe storms and heavy snow
  • Location: Near Hull

Isn't it fairly simple? A low risk of storms in but could be severe if they do form in the black area, and a moderate risk of storms in the orange but not severe likely to be severe. Although a probability of severe would make more sense than a binary. 

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Posted
  • Location: Leeds
  • Location: Leeds
3 minutes ago, Nick L said:

Just found an explanation for the risk areas and I am still none the wiser...So that SVR is basically a slight slight risk area?

http://www.convectiveweather.co.uk/criteriakey.php

Can't say I'm a fan of this UK emulation of SPC forecasts at the best of times.

My interpretation is that it's like when Estofex have a Level 2 in a 15% lightning area - it's probably not going to happen, but if it does happen then it could be rough.

Agreed, there's tons of silly SPC emulations out there, but whoever runs convectiveweather is very good, and is often quite on the money.

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