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Storm & Convective Discussion - 7th August Onwards


Nick F

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Posted
  • Location: Bexley
  • Location: Bexley

Wasn’t sure where to post this so this seemed as good as any. Currently overseas and hotel took a direct hit from a storm. I was sat on a wall still wet from the rain/pool when a bolt hit very very close. So close in fact I felt a surge of electricity in one leg, it involuntary kicked out and hairs all stood on end. I clearly wasn’t ‘struck’ but what was it?  Pain was like a strong electric shock over in a second. Loudest thunder I’ve ever heard to finish it off . I’m guessing as I was wet I took some of the electric discharge??

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Posted
  • Location: 150m asl Hadfield, Glossop Peak District
  • Weather Preferences: All
  • Location: 150m asl Hadfield, Glossop Peak District

Probably a voltage gradient.

The voltage drops in a ring surrounding the strike. If for instance a cow was stood with two legs closer to the strike, the voltage difference in the ground between them and the hind legs could be tens of thousands of volts. the cow would be a current path in parallel with the ground resistance.

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Posted
  • Location: Bexley
  • Location: Bexley

Appreciate the replies. Never felt anything like it. Took cover further into the bar area and the next strike hit the lightning conductor on the roof. Saw the sparks fly off it. Never felt power like it. The waiter gave the sign of the cross which made me laugh. Intense 30mins. Love this part of the world 

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Posted
  • Location: London
  • Weather Preferences: Hot
  • Location: London
8 minutes ago, Reevesie1 said:

Appreciate the replies. Never felt anything like it. Took cover further into the bar area and the next strike hit the lightning conductor on the roof. Saw the sparks fly off it. Never felt power like it. The waiter gave the sign of the cross which made me laugh. Intense 30mins. Love this part of the world 

I wonder what part of the world this is, italy perhaps?  Or maybe it's b****y Lincolnshire!

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Posted
  • Location: Norwich, Norfolk, East Anglia
  • Weather Preferences: Sunny, stormy and I don't dislike rain only cold
  • Location: Norwich, Norfolk, East Anglia
8 hours ago, Reevesie1 said:

Haha... Mexico. Lots of energy in that water keeps rolling in 

Mexico! My only post on it cause I don't want to bombard this off topic but I love Mexico. When I went in August for 3 weeks 4 years ago. I saw countless storms near and far. During the rainy season in Mexico city there was a thunderstorm nearly every evening I was there, was bizarre looking at the forecast cause it was showing storms every day twice a day. 2 to note, one had frequent cloud to cloud lightning that was really impressive, the other was like a part in war of the worlds, surface based and a CG once every 10 seconds with a real crack of thunder. That was about 3 hours away from the city. The trip was awesome anyway but all those were the icing on the cake. Even thought I saw a funnel from the plane before I'd even got off. Driven by my girlfriend's uncle to our first destination from the airport the first of many storms. Will always remember that trip! I'm glad you got out of it ok, what an experience for you!

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

Day 2 Convective Outlook

VALID 06:00 UTC Wed 22 Aug 2018 - 05:59 UTC Thu 23 Aug 2018

ISSUED 17:03 UTC Tue 21 Aug 2018

ISSUED BY: Dan

Both very low risks. Isolated lightning will be possible on Wednesday afternoon / early evening along or just ahead of the cold front as subtle forcing aloft may be enough to release some marginal mid-level instability. Behind the front, cold air aloft atop warm SSTs will generate some marginal instability, with scattered showers likely over NW Scotland by Wednesday evening and overnight into Thursday. Forecast profiles look rather dry and capped, with any convection possibly fairly shallow in depth - and hence it seems unlikely there will be much (if any) lightning activity. Best potential, albeit still rather low, will exist over Shetland.

http://convectiveweather.co.uk/forecast.php?date=2018-08-22

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On 17/08/2018 at 23:21, Had Worse said:

Probably a voltage gradient.

The voltage drops in a ring surrounding the strike. If for instance a cow was stood with two legs closer to the strike, the voltage difference in the ground between them and the hind legs could be tens of thousands of volts. the cow would be a current path in parallel with the ground resistance.

Hence why if an excavator cuts a HV cable the operator  must leave the machine with feet close together in a shuffling  movment  ,if not resistance could be fatal 

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Posted
  • Location: Godalming
  • Weather Preferences: Plumes and streamers
  • Location: Godalming
15 hours ago, Another Kent clipper said:

@Flash bang flash bang etc

I know, the late April and late May MCS glubs were just a tease building up to summer of hot blah.

You'll have to remove the etc off your username at this rate

But that would still suggest that there was two flashes

Edited by Flash bang flash bang etc
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Posted
  • Location: Pemberton, Wigan, 54 M ASL. 53.53,-2.67
  • Weather Preferences: Winter - snow, Irish sea convection. Summer - thunderstorms, hot sunny days
  • Location: Pemberton, Wigan, 54 M ASL. 53.53,-2.67

 Next few days look rather interesting. Maybe repeat of the 10th of August for me at some point.  Slightly colder 500 hPa temps this time. 

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

Day 1 Convective Outlook

VALID 06:00 UTC Thu 23 Aug 2018 - 05:59 UTC Fri 24 Aug 2018

ISSUED 05:33 UTC Thu 23 Aug 2018

ISSUED BY: Dan

Upper trough and associated cooling aloft will overspread northern portions of the British Isles during Thursday, steepening lapse rates and generating a few hundred J/kg CAPE. Behind the secondary cold front, numerous showers are likely to develop during the afternoon and evening hours, persisting overnight in areas exposed to the northwesterly wind. Some gusty winds and small hail will be possible with the strongest cores, and while there could be a few lightning strikes rather weak shear and marginal instability suggests that lightning activity will tend to be rather isolated / sporadic and hence difficult to highlight any specific areas with a greater risk.

 
The secondary cold front will also become more convective in nature by Thursday afternoon as it moves across north Wales, northern England and the north Midlands. Instability will be marginal, but with a strongly-sheared environment there will be scope for some line segments to develop, which could produce some isolated/sporadic lightning and strong gusts of wind. A low-end SLGT has been issued to highlight the region of interest, but there will likely be many areas within the SLGT that remain void of lightning.
 
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Posted
  • Location: Whaley Bridge - Peak District
  • Location: Whaley Bridge - Peak District

A few rumbles to the west towards Macclesfield way, ominously dark looking in that direction too with moderate rain falling here.

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

Day 2 Convective Outlook

VALID 06:00 UTC Fri 24 Aug 2018 - 05:59 UTC Sat 25 Aug 2018

ISSUED 20:14 UTC Thu 23 Aug 2018

ISSUED BY: null

Broad upper trough will cover the British Isles on Friday, the associated cold air aloft atop warm SSTs and diurnal heating inland helping to steepen lapse rates and generate several hundred J/kg CAPE. One trough axis will clear eastern Britain early on Friday morning, leaving elements of upper ridging in its wake over southern Britain for a time during the morning.

 
Numerous showers are likely to develop on Friday morning across central and northern parts of the British Isles, the risk extending farther south during the afternoon and evening hours as stronger forcing associated with a shortwave slides SE-wards - across Northern Ireland during the morning, into Wales/Midlands during the afternoon and S / SE England during the evening.
While some isolated / sporadic lightning is possible virtually anywhere given the extensive coverage of showers and marginal instability, the risk of lightning is probably greatest in this zone from Northern Ireland through Wales / Midlands to S / SE England, given an overlap of stronger shear and better forcing allowing some cell organisation to occur. A low-end SLGT has been issued to highlight this potential, with extensions over the North Sea and English Channel where some lightning activity seems likely during the late afternoon / evening hours.
 
In general, profiles are more unstable but with weak shear in the north, and more capped but stronger shear farther south - somewhere in the middle, with an overlap of both shear and instability, would be favoured for the best lightning potential. The strongest cells may produce hail up to 1.5cm in diameter and wind gusts of 40-50mph locally.

http://convectiveweather.co.uk/forecast.php?date=2018-08-24

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

Storm & Convective Forecast

stormmap_240818.thumb.png.effa26fd0fb5dc7aef32a630f9f92a1c.png

Issued 2018-08-24 09:34:26
Valid: 24/08/2018 00z to 25/08/2018 00z

https://www.netweather.tv/weather-forecasts/uk/convective

THUNDERSTORM OUTLOOK - FRIDAY 24TH AUGUST 2018

Synopsis

Large-scale upper trough axis will lie across the British Isles Friday morning, before the axis tends to shift east toward Scandinavia into the evening. A low pressure system centred off the coast of Norway will pull in a cool polar maritime W to NWly flow across the UK, which becoming increasingly unstable to surface heating - supporting increasingly widespread showers and thunderstorms.

... UK and IRELAND ...

Showers from the word go this morning across western areas, frequent and heavy across the NW, will spread or develop more widely through the day across much of mainland UK, as surface heating beneath mid-level temps of minus 20C at 500mb creates steep lapse rates. Some of the heavier showers will produce hail and sporadic lightning, where heavy showers merge, there is potential for some localised flooding. Difficult to highlight where thunderstorms are most likely, though W Scotland, NW England and N. Ireland / NW Ireland seem at greatest chance based on models. Showers may not arrive across SE England until the evening.

Late afternoon and through the evening, models indicate a shortwave trough, marked by flow veering from W to NW, moving E/SE across Ireland, Wales and then southern England bringing a more organised area of heavy showers and perhaps embedded isolated thunder with it. 40-50 knts of deep layer shear enhanced by strong jet stream across Sern UK will perhaps organise convection into clusters which will bring mainly a threat of localised flooding and also strong wind gusts (35-45 mph)

 

 

Edited by Nick F
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Posted
  • Location: Pemberton, Wigan, 54 M ASL. 53.53,-2.67
  • Weather Preferences: Winter - snow, Irish sea convection. Summer - thunderstorms, hot sunny days
  • Location: Pemberton, Wigan, 54 M ASL. 53.53,-2.67

 16.6°C currently, 4°C warmer than forecast by the WRF. Lightning to my south-west. 

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Posted
  • Location: Peterborough, Cambridgeshire
  • Weather Preferences: Thunder snow is the best phenomenon
  • Location: Peterborough, Cambridgeshire
49 minutes ago, East_England_Stormchaser91 said:

Wow, didn’t see that coming, proper loud rumbles and torrential rain! 

Im to the south , we missed it all must be very,very localised, sunny here still!

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