Storm & Convective Discussion - 16/07/15 onwards

[Greeny]

I wonder if Nick Finnis will do a storm forecast tomorrow for Scotland, moderate Cape values are forcast with a trough bringing temps of between -25 and -32 at 500mb heights sweeping across Scotland from West to East according to GFS. Lapse rates get pretty steep during the afternoon. Some strong DLS skirts Scotland down through northern England that could aid storms and bring something a little more severe. The strongest part of the jetsteam looks to reside over the area. Going to be fairly gusty too however there are only pockets of Low Layer Shear forecast by GFS so in the main pretty weak there but you never know.

 

Are there any members in Scotland that will give storm reports for tomorrow if any do fire?

[Cakie]

Oooh! Parisian storms can be really spectacular. I had a great one a few years ago when I happened to miss my flight and had to stay over an extra night in a hotel at CDG. I was on an upper floor so I had a great view of the almost constant CG strikes all around the airfield. There was complete daytime darkness in the morning - it was an incredible experience - made even more eerie by the fact that the airport was closed to air traffic due to the storm. You might even get the privilege of seeing a direct strike on the Tower or La Défense. Enjoy it - I'll be in Limousin from Monday where we should have some nice action as well...

dont say this. We are up in the Paris/Versailles area from Wednesday until Sunday when we are supposed to fly out. I'm happy for a storm but don't fancy being delayed

[Nick F]

Yep, have had an eye on Saturday's potential over Scotland over last few days and all the parameters are converging to suggest some lively storms with a low-end severe risk over southern Scotland.

500mb cold pool (circa -25C) moves over Scotland creating steep lapse rates which will be enhanced by surface heating, 400-700 j/kg CAPE. Despite unimpressive surface dew points, the temp and dew point spreads should be small enough for surface based storms. Total totals (TT) index is high, TT field a measure of how unstable atmosphere is based on 850-500mb lapse rate plus 850mb dew point. Index greater than 52 indicates severe storms possible, as indicated on chart below:

Using wind shear charts points towards southern Scotland for best severe potential where storms will benefit from strongest DL shear in the order of 40-60 knots, which suggests marginally large hail possible and strong wind gusts, lightning wizard has significant tornado parameter and low LCLs too here, so favourable for a rotating updrafts and spin ups

Edited July 31, 2015 by Nick F

[Greeny]

Yep, have had an eye on Saturday's potential over Scotland over last few days and all the parameters are converging to suggest some lively storms with a low-end severe risk over southern Scotland.

500mb cold pool (circa -25C) moves over Scotland creating steep lapse rates which will be enhanced by surface heating, 400-700 j/kg CAPE. Despite unimpressive surface dew points, the temp and dew point spreads should be small enough for surface based storms. Total totals (TT) index is high, TT field a measure of how unstable atmosphere is based on 850-500mb lapse rate plus 850mb dew point. Index greater than 52 indicates severe storms possible, as indicated on chart below:

viewimage (7).png

Using wind shear charts points towards southern Scotland for best severe potential where storms will benefit from strongest DL shear in the order of 40-60 knots, which suggests marginally large hail possible and strong wind gusts, lightning wizard has significant tornado parameter and low LCLs too here, so favourable for a rotating updrafts and spin ups

gfs_stp_eur27.pnggfs_lfc_eur27.png

Ah there we go nice to get some backup for my observations. I like the last chart, putting that one in the bag for future forecasts! Thanks Nick.

[Nick F]

Have issued a storm forecast for Saturday here : http://www.netweather.tv/index.cgi?action=convective;sess=

[Greeny]

http://www.estofex.org/

Surpised to see Estofex not so on board with anything severe.

[Spikecollie]

dont say this. We are up in the Paris/Versailles area from Wednesday until Sunday when we are supposed to fly out. I'm happy for a storm but don't fancy being delayed

I don't think you'll get anything severe up there, further south where I am looks more likely, but you might get a nice display. Aside from the charts, I like to use meteolafleche.fr for good French forecasting, but they're on holiday so if you want their commentary you'll have to follow them on Facebook or Twitter.

 

Have a wonderful time in Paris...

[Staffordshire]

I'm in Paris as from Wednesday. By the look of things, I will have my camera at the ready because the models are showing some stormtastic charts!

Never experienced a real French classic yet, but this could be on the cards!

i have just came back and it is certainaly warming up there

[East_England_Stormchaser91]

i have just came back and it is certainaly warming up there

Sounds awesome! Will definitely be on the watch there and update back to here.

Meanwhile, a storm has gone into a bit of overdrive between Corsica and Italy, throwing out 230+ strikes per minute!!!

Edit: 280+ strikes now :O

Edited August 1, 2015 by East_England_Stormchaser91

[Weather-history]

Disappointing day with those showers in the afternoon

[Thunderbolt_]

August is statistically the most thunder-prone month of the year in the UK, so I would like to squeeze in another good Spanish plume before the end of the summer. If I could choose the date, then hopefully it will happen sometime around the 10th because that's my 18th birthday, and there's no better weather than heat and thunder on your birthday, in my opinion.

[stainesbloke]

August is statistically the most thunder-prone month of the year in the UK, so I would like to squeeze in another good Spanish plume before the end of the summer. If I could choose the date, then hopefully it will happen sometime around the 10th because that's my 18th birthday, and there's no better weather than heat and thunder on your birthday, in my opinion.

There isn't much better weather than heat and thunder full stop lol...really hope we get decent amounts of both this August. This chilly dreary 'weather' is boring me silly.

[Mokidugway]

I'll will see a storm this month but most likley when I'm on holiday !..

[Mokidugway]

Some quite heavy rain gone through ,feels almost plume like !!.

[Weather-history]

Thundery looking sky with virga.

[A.J]

some elevated convection over SW England, the West Country & South Wales triggered by a trough tracking in from the west.....a few sporadic strikes showing up on various detectors in these areas.......certainly some Ac Floccus in the western skies here

[elfinpunk]

Where on earth did that spring from... I happen to look out of the window and see a few lines of almost text book AcCas and then it suddenly starts raining huge drops of rain, I get up for a closer look and the southern sky is a mass of undulatus!

[dragon falls]

Same here gone dark big drops of rain looks Thundery feels humid

[legritter]

Looks like some elevated action may just break out in one or two places ,and yes we have just had very large raindrops here on mendip .

All gone now but looking at radar perhaps something more noteworthy for west and s west wales later .

[Raidan]

Been a very nice day today but feels humid now and have had big rain drops hope that band of rain coming in gives off a few sparks.

[Raidan]

Hmmm just looked at Rain Today and the rain seems to be heading more into Wales than the South West so hopes of something thundery have lowered so what.

[Allseasons-Si]

A couple of sferics over Gloucester,rogue?

 

they seem to correspond with that developing ppn in that area.

 

rogue

Edited August 2, 2015 by Allseasons-si

[MP-R]

Had the 50p size drops here too. Some lovely plumey looking skies this evening.

[Allseasons-Si]

Can anyone comfirm they have heard thunder in Gloucester,two sferics back on the map there.

[twister2005]

Hi yes was out walking dogs lightning and thunder