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Spanish plume anyone? Storm and convective discussion 17th July Onwards


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Whilst further homegrown t/storms may happen, this is primarily about French imports into Southern and South-Eastern England overnight.

 

The action, proper, starts with a convergence zone stretching across the majority of Northern France

 

Posted Imagecz.png

 

This is the trigger that will initiate convection. Convection occurs in a high theta-w environment,

 

Posted Imagetw1.gifPosted Imagetw2.gifPosted Imagetw3.gifPosted Imagetw4.gifPosted Imagetw5.gif

 

As the higher theta-w air moves in it will start to feel very very uncomfortable. The cells formed over N France will move North into Southern Britain which will be in a moderately convective environment (KI=32,LI=-1), however, it will be capped (CIN=22) preventing any further storm development.

 

Posted Imageskew-t.gif

 

However, and this I think is the crucial part - the temperature and the moisture content from the theta-w air will build under the cap, and then this little fella,

 

Posted Image16337831.gif

 

will skirt overhead and break the cap for us to allow for further cell development.

 

Important to note: the cells are not going to be made here, this evening, they are being imported; this is all about the chance of them dying off before reaching us, and, based on above, I don't think that cells dying to rain showers is going to happen.

 

Saturday is the day for homegrown with the added fun of loads of CAPE, and a cold front :)

 

Question........?

 

Theta w

Theta e

 

Please in a potted science lesson, explain/define the above, and how many letters go in front of Theta please??

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This explosion here is what we like!  

New strikes appearing in the channel peeps ahead of MCS 2 - active very quickly too

A couple more pictures  This part was rotating crazily A VERY close lightning strike (amazing picture, I know lol) And this one... I am so annoyed that it went wrong!  

Posted Images

Two big flashes of lovely silvery lightning and booming thunder!

EDIT: 5th flash and rumble! And the heavens have opened :D Looks like it's here for a while

Edited by Convective
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Had constant lightning from about 1am-2:30am but the thunder wasn't so frequent at first. I then got woken up at around 3:45am by a short downpour, which produced a bit of thunder and lightning.

 

That first storm was possibly the best I've ever seen in terms of the quantity of lightning :D I'll put photos/videos up later.

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Shower came through here with a few meek rumbles.

Can people who live in the SE, specifically around Cambridgeshire and surrounding counties suggest a few southerly view points? I'm likely to be travelling that way tonight, depending on developments :-)

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Torrential rain around hour ago over Derby but I was in work so couldn't hear any thunder, however it looks from the lightning detectors like there were sferics picked up round and about plus Spenna'82 confirms some north of here.

 

That MUCAPE chart from the NMM model earlier on in the thread shows huge CAPE and a LI of -11 at midnight in the SE tonight! If this is what is expected down there than I shall be making the journey down regardless of distance as the lightning in these storms (if they form) would be immense. It's always a toss up though, do I stay and save the petrol money or go for it. Last night I decided to stay at home and ended up missing out. 

Edited by Supacell
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Looks like there are a few strikes to the east of Sheffield and up towards Rotherham / Doncaster.  As usual the track seems to be up the A1 / M1

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why have the met office grossly under-estimated the ammount of cloud cover for the Lincs area, it was supposed to be sunny at 7am right through the day, and here we are 11.30, its raining and no signs of any sunshine, temps due to be 31c and we know we are not going to get above 22/23 in my view, these conditions must surely knock out any chances of storms here northwards.

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Saturday is the day for homegrown with the added fun of loads of CAPE, and a cold front :)

 

Is it bad that the words  loads of CAPE, and a cold front gave me shivvers ?

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Northern England were never going to get storms last night though, and don't have much chance this week either, (a slim chance on Saturday, away from the coast).. This is an almost entirely southern-based event, as that's where the heat and humidity is/will be. North of a line from say Wrexham to the opposite shore, it's simple won't be warm/humid enough to ensure some good thunderstorm developing (perhaps apart from some orographic forcing?). As I see it, a wedge of relatively cool and fresh air invades west of the Pennines which nullifies the chance of storms there.

I really don't know what you're talking about. There was a short but severe thunderstorm here about 8am, with one particularly close strike which sounded like an explosion. Scared the crap out of me!

 

It's fine and sunny again now, and should be even more humid with the sun heating the surface water.

Edited by AderynCoch
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This is what's coming out of France, tonight ...

 

post-5986-0-96130500-1405679760_thumb.gi

 

Is it bad that the words  loads of CAPE, and a cold front gave me shivvers ?

 

Maybe, but adding capped hot humid air as well, should!!! :)

Edited by Sparkicle
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The remements of last night's fun and games are approaching (as expected they have weakened) May get something but not 100% sure

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These storms will form irrespective of cloud cover as they will be upper based. In any case very warm sunny breaks for most this afternoon.

Edited by TonyH
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Just to make it clear, its not today which has the potential for great homegrown activity, thats for tomorrow! (however the odd thunderstorm could be expected in East Anglia)....today is all about imports from France!

Edited by Panayiotis
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Amber warning from the Met Office just issued for a large chunk of the country, including here, so that's doomed it!

 

http://www.metoffice.gov.uk/public/weather/warnings

 

Posted Image2014-7-19.jpg

 

Very surprised the SE isn't included in the Amber as this is the area that has an Estofex level 2.

 

:D Panayiotis, you posted at the same time - that explains it.

Edited by Supacell
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Just in case no-one has seen it previously, this is what Estofex has got for us, with a remarkable level 2 for the far SE! It ties in nicely with this post from earlier ( http://forum.netweather.tv/index.php?app=forums&module=forums&section=findpost&pid=3006376 ), some points from the main passage:

 

"As the main trough approaches France, the mid-level flow is expected to back and intensify, yielding a strongly sheared environment with about 20-25 m/s of 0-6 km shear. In the lower troposphere, a convergence zone should establish approximately near a line from Le Havre to La Rochelle."

 

"Current thinking is that the air-mass slightly to the east of the surface convergence line will be strongly capped. Near the convergence line and to its west, however, convection is likely to break out during the evening as lower tropospheric temperatures drop somewhat in response to quasi-geostrophic forcing for upward motion. Model guidance show very high precipitation rates. It is likely that a few supercells will form initially."

 

"The focal point of the threat should travel northward across the English Channel and may well affect southeastern England during the 00-06 UTC time frame."

 

Just to make it clear, its not today which has the potential for great homegrown activity, thats for tomorrow! (however the odd thunderstorm could be expected in East Anglia)....today is all about imports from France!

post-17320-0-86281100-1405680473_thumb.p

post-17320-0-32508900-1405680474_thumb.p

Edited by Panayiotis
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