Storm & Convective Discussion 12z 21/7/14 ------>

[LeeRoyxD]

Thunder just now in Seaford

[audiotech]

Nothing electrical but seen a lot convective showers, some with tower and anvils through the day. Not sure how to describe it but the cloud at the edge/top of the showers seems to have been particularly fluffy today, a sort of white fuzzy fluff, rather than a smooth bubbly looking tower/anvil. Is it the stronger wind that causes this?

 

That Bristol channel streamer has been going at varying intensities for over 24hrs now. If it were winter they'd have lot of snow over there by now.

[Raidan]

Torrential rain this morning street is like a river.

[Allseasons-Si]

What a weekend it has been for storm fans,here's a few lightning stills from the storms we had from friday-sun

 

 

 

 

 

 

ex bertha will surely be remembered.

 

 

[Evening thunder]

A good day for showery skies and CB's here yesterday, although not much from before 3 to 9pm. Had one brief very heavy shower, several torrential showers went just to the north as per usual this summer, or if not a couple went to the south.

 

A couple relatively distant rumbles to the NNW, brings this years thunder or lightning seen days to 14 which is reasonable but most have been things like today, only a few decent events i.e storms overhead, and missed a couple of them.

 

When I looked yesterday evening Denmark/far north Germany was getting a load of good looking night time storms coming off the North Sea, generated by the warm SST's that way, and that area still is now 12 hours later!  Shame that can't happen here. Decent CAPE levels generated around the Baltic forecast for the next week or so too.

[NL]

What a weekend it has been for storm fans,here's a few lightning stills from the storms we had from friday-sun

 

ex bertha will surely be remembered.

Ex Bertha wont be remembered here in Tyne & Wear. A bit breezy and wet for August for sure but nothing outstanding.

[Nick F]

I'm not quite sure how to word this question but here goes.Are there certain parts of a Cb cloud that is more likely to produce lightning than others.? I have often witnessed storms where the strikes seem to come from the same area within a cloud or am I imagining this.?

 

From experience of storm chasing in the USA, the updraft area of a storm tends to produce most of the cloud-to-ground strikes, particularly with new updrafts and where rain shafts are forming. Though obviously c-to-g lightning can occur anywhere in the storm, even when where you aren't directly underneath it when they come out of the overspreading anvil. IC lightning can occur anywhere in the storm.

 

Anyway, storm forecast issued for today, storms perhaps not so numerous or widespread as yesterday, but should be some good clean convective cloudscapes:

 

http://www.netweather.tv/index.cgi?action=convective;sess=

Edited August 12, 2014 by Nick F

[Chris.R]

This year I have had 11 days with thunder heard, which is by far and away the record in the last 10 years. Shows how bad things have been around here though, if 14 days is only reasonable in other places.

[BrickFielder]

  Slight risk of thudnerstorms today many in Wales but perhaps stretching into the Midlands.

Steeping laspe rates across Wales and midlands as a thin weak band of vorticity approaches.

  Vortiity shows up on lightning wizard charts as follows.

 

  Upper level charts show a small area of divergence aloft, although winds are weak.

 

  Some slight turning of the winds through the atmosphere.

 

 Instability looks very limited, most likely by the weak temperatures today.

 

Overall I think the following areas late afternoon have some potential.

 

Blustery perhaps thundery showers most likely.  Limitations for severe weather are higher cloud bases, weak instability, not very high cloud tops.

[BrickFielder]

I'm not quite sure how to word this question but here goes.Are there certain parts of a Cb cloud that is more likely to produce lightning than others.? I have often witnessed storms where the strikes seem to come from the same area within a cloud or am I imagining this.?

 

 

Lightning is a result of different size ice particles within a cloud. With a strong updraft then smaller ice particles are lifted high up while larger ice particles will tend to bounce around in the bottom layers of the cloud until they are heavy enough to fall. As these two ice particles pass each other and water droplets clash with them then they tend to have different electrical properties. Causing the top region of the cloud to accumulate a positive charge while the lower level accumulates a negative charge.

 

Depending on the freezing level within the cloud then lightning will tend to form from different heights in the cloud. The higher the freezing point the less cloud to ground lightning will form. The stronger the updraft then more large hail particles will be in the lower part of the cloud. Outflow dominant parts of a storm will tend to loose charge from the bottom of the cloud as hail and rain falls, so here you might expect more cloud to cloud lightning.

 

So for any particular storm it depends on the freezing level (Higher up means less cloud to ground lightning as it might have to travel further) and the strength of the updraft at various points (updrafts will tend to increase the charge) and the right conditions for lightning are likely to form in the same part of the storm.

 

Not sure whether that answers your question but you might expect lightning from the same parts of the storm.

[Flash bang flash bang etc]

Hey just a quick one - I am working on an app idea where there is a map of the UK and anyone who wants to can mark potential thunderstorm risk for the following day. You can then submit this and it will give you an image based on everyone's input - darker areas should be the areas more likely to see thunder (though this depends on the accuracy of the inputted maps).

 

It's actually a good way for me to try out some code I was working on anyway but might prove an additional source of data for storm chasers.

 

What do people think?

 

You can be as honest as you like - I've only spent a couple of hours on it so if it doesn't work I'm not too worried!

[TonyH]

From experience of storm chasing in the USA, the updraft area of a storm tends to produce most of the cloud-to-ground strikes, particularly with new updrafts and where rain shafts are forming. Though obviously c-to-g lightning can occur anywhere in the storm, even when where you aren't directly underneath it when they come out of the overspreading anvil. IC lightning can occur anywhere in the storm.

 

Anyway, storm forecast issued for today, storms perhaps not so numerous or widespread as yesterday, but should be some good clean convective cloudscapes:

 

http://www.netweather.tv/index.cgi?action=convective;sess=

Yes Nick my obsessive viewing of the radar/ sferics this Summer is proving that to be the case, the leading cell tending be the liveliest for lightning returns, as the ones behind weaken.

[TonyH]

Re thunder heard days:

 

11 so far here this year which is remarkable and equals my local record of 11 in 2006 (whole year). As remarkable is that there has been thunder heard in every month so far! 

 

A full yearly breakdown for this location:

2006 11 (July 3)
2007 6 (32mm in one hour thunderstorm June)
2008 8 (May 4 out of 5 day run)
2009 6 (June 3)
2010 5
2011 2
2012 3
2013 4

Total 45 days over 8 years = 5.6 days/ annum mean
Ties  in quite well with MO map which has us in the 6 - 8 day zone

http://www.metoffice.gov.uk/climate/uk/averages/6190_1km/Thunder_Average_1961-1990_17.gif

 

Reviewing  my thunder records kept in Coventry from 1975 to 1984:

 

Mean thunder days annually 14.4

Most thunder days in a year 25 in 1983

Least in a year 8 days 1977

 

Most in a month 11 days in June 1982

Edited August 12, 2014 by TonyH

[TonyH]

Sferics close to the Malverns

[Arnie Pie]

Some sharp showers begining to come in to our area atm

Hopefully giving us at least some `bows like yesterdays spectacular showing

[Lauren]

Hey just a quick one - I am working on an app idea where there is a map of the UK and anyone who wants to can mark potential thunderstorm risk for the following day. You can then submit this and it will give you an image based on everyone's input - darker areas should be the areas more likely to see thunder (though this depends on the accuracy of the inputted maps).

 

It's actually a good way for me to try out some code I was working on anyway but might prove an additional source of data for storm chasers.

 

What do people think?

 

You can be as honest as you like - I've only spent a couple of hours on it so if it doesn't work I'm not too worried!

 

What would stop people randomly posting incorrect risk and thus messing with the overall map?

[Arnie Pie]

Thunder heard in Brum

[Staffordshire]

What would stop people randomly posting incorrect risk and thus messing with the overall map?

this was my thinking, a very good idea, however there would likely be a lot of bias to peoples back yard, i like the idea of it however and think it would be something to develop

[Costa Del Fal]

Thunderstorm just to my south currently but giving some nice booms of thunder. Had some rain too.

[matt_in_dudley]

Huge storm to my east. Always east.

[Staffordshire]

you sure matt? that would indicate i had a decent shot but zilch here?

sorry matt i thought for some reason you were in walsall, my bad!

[Costa Del Fal]

That storm is creating a jet black sky against the sun. Seemed to be a visible hail core too.

[Bluebreezer54]

Thunder heard in Brum

Cracking views on your Brumcam again Arnie

Edited August 12, 2014 by Bluebreezer54

[Arnie Pie]

yep hailcore visible in Brum

Edit Cheers Blue...all of the lightning seemed to snook to the S of view

Edited August 12, 2014 by Arnie Pie

[Mapantz]

yep hailcore visible in BrumEdit Cheers Blue...all of the lightning seemed to snook to the S of view

Watching it right now. Works good on MX player.