22nd into 23rd Aug 2011 - Storm/convective Forecast Discussion And Reports

[gpspete]

you may wish too keep an eye on my website ignore most the most the website its no longer working properly and i am rebuilding it at present

but my lightning page is working http://www.bicesterw...uk/StormVue.php

the wide area storm page is several detectors correlated to try and correct positions but may show less than the true amount of strikes

if storms are local my pc may be turned off so it may go down though

Edited August 22, 2011 by gpspete

[EML Network]

As always Brighton seems to be right on the edge of the action, sod's law as we had some very active storms late June, which i missed due to being at work, and now that im at home this evening, i'd likely have a better chance of seeing something if I were at work ...ggggrrrrrr

Still I'm not really sure any of us are going to get anything , other than a good soaking, which is at least something to look forward to.

Just goes to show how dull this summer has been, when I actually get excited about the prospect of it raining heavily.

[Harry]

Currently parked in Folkestone overlooking the harbour, lovely spot, very hazy, poor vis, reminds me of the precursor to a large storm which hopped across channel in 2007 the classic murkyness! Incidentally my wife has kicked me out today, cant go anywhere else until she calms down,so am doing some storm chasing instead, anyone on south coast between dover and hastings over next 24 hrs let me know

Aw mate that's a bit raw! You are in arguably the best spot for spotting storms tonight - you might well be waiting until the wee early hours (2-3am I suspect) IF anything should come along.

[Coast]

You are in arguably the best spot for spotting storms tonight

The Dungeness/Lydd area and maybe Beachy Head. I've still got to get into work first thing in the morning so I will be viewing from the bedroom window if I hear anything, then possibly a quick sortie out to the seafront if it really kicks off.

Got the MetO rain chart now that someone was asking about earlier

SST's still OK and currently 18.2 DgC in Pevensey Bay and 17.9 DgC in Folkestone:

http://www.channelco...me_data/charts/

[GadgetWeatherFreak]

I live in the Brookland area near Lydd which is a few miles from you but have driven to Folkestone to start with, i've got my supplies i'm here until tomorrow, one thing i haven't got and thats coffee ! If i had known that i was being kicked out i would've made a big flask up, i kind of feel i'm on the frontline here, wish i didn't have a glass roof, not sure the faraday effect will work if i get struck !

[Eskimo]

Hi guys, I'm new to this thread, mainly based over at 'theweatheroutlook' but came over here because it's interesting what people are saying about this set up. Not sure what will happen tonight, but as someone else mentioned, there is a probability that a lot of the convection will get going 8pm onwards when the air becomes more moist and prone to convection. With storms brewing over Western France close to the centre of the low pressure at the moment, the prognosis is that most of the convection will appear over the same area and slowly but surely that precipitation and the unstable airmass will push over the channel towards the UK. Now if anyone is interested in a time when the storms will approach and make landfall here in the sunny isles then you are looking at 11pm onwards. But my guess is as good as anyone else's.

Edited August 22, 2011 by Paul Carter

[tomp456]

Please come to Worthing. You know you want to.

Good luck tonight y'all

[Coast]

Hi guys, I'm new to this thread, mainly based over at 'theweatheroutlook' but came over here because it's interesting what people are saying about this set up.

Hi Paul and welcome! What's the feeling on TWO for the area likely to see any potential?

[Harry]

Hi guys, I'm new to this thread, mainly based over at 'theweatheroutlook' but came over here because it's interesting what people are saying about this set up. Not sure what will happen tonight, but as someone else mentioned, there is a probability that a lot of the convection will get going 8pm onwards when the air becomes more moist and prone to convection. With storms brewing over Central France close to the centre of the low pressure at the moment, the prognosis is that most of the convection will appear over the same area and slowly but surely that precipitation and the unstable airmass will push over the channel towards the UK. Now if anyone is interested in a time when the storms will approach and make landfall here in the sunny isles then you are looking at 11pm onwards. But my guess is as good as anyone else's.

Hi mate welcome to the forum!

Yeah if you're looking for much more info than you already have then you might be a little disappointed!

As with pretty much every forum and weather related website there's low confidence in respect of where in the UK, if anywhere, will see convective stuff or whether it will merge to give more frontal type precip with occasional embedded CBs bringing sporadic thunder.

Heavy/torrential rain is pretty much certain in a zone ranging from Norwich diagonally down towards the IoW and eastwards towards Kent. BBC at the moment pointing to more clustered thundery showers rather than prolonged frontal rain, whereas their own pressure charts (courtesy of the MetO) points towards more of a frontal feature.......throw in the potential for an MCS and it really is a guessing game..........

Edited August 22, 2011 by Harry

[gpspete]

just been sat in garden watching the local gliders (about 1/4m to airfield) mostly cable launched today they are certainly finding some lift and climbing rapidly after release

perhaps we may get some local grown later

the sferics in channel have died away know but i still hope for later

Edited August 22, 2011 by gpspete

[Azores Hi]

One thing is for certain, the area north east of the low in the BoB is getting rather good at propagating MCS's. I'm just watching the 5th one of the day pop up on Radar just west of Rennes.

The potential is certainly there!

Edited August 22, 2011 by Azores Hi

[Harry]

MetO reverted back to "heavy rain, thundery at times with local downpours possible"

Confidence is really not all there across the board.....

[chionomaniac]

I'm going to stick my neck out waaaaaay too far now. Here's where I think might catch it and I'm going for 0230 hrs to 0400 hrs, 23/08/11 for the best time:

Also just seen this for storm helicity:

Are you basing this outlook in the GFS, Coast?

The 12Z NAE is far more favourable:

[Coast]

just been sat in garden watching the local gliders (about 1/4m to airfield) mostly cable launched today they are certainly finding some lift and climbing rapidly after release

Are you basing this outlook in the GFS, Coast?

The 12Z NAE is far more favourable:

Well mostly, yes. Unfortunately they have more charts where I can tell what they mean!! I have looked at some Met O stuff and Netweather's own NMM charts and they seem to match for the wee small hours currently

Some critical values for Total-Totals Index, only to be used for coverage of thunderstorm if they occur, and to be used in combination with CAPE, LI and KO index:

44-45 = isolated thunderstorms

46-51 = scattered thunderstorm

52-55 = scattered to frequent thunderstorms

[Harry]

GFS looks pants to say the least!

[Joey.G]

Think now may be a good time to re-share this link that somebody else once posted here. You can watch the progress of the low over the past 24 hours in one animation

http://www.yr.no/satellitt/europa_animasjon.html

[winter watcher]

Afternoon all, The question i would like to put to you all is what has gone wrong since this morning? I checked in then and everyone had a certain amount of confidence for tonight. So whats changed in the last few hours it all seems doom and gloom now?

[Robbie Garrett]

Rain showers and thunderstorm rain for Heathrow EGLL 221115Z 2212/2318 07005KT CAVOK TEMPO 2301/2308 7000 SHRA TSRA

Between 01 and 08z tomorrow that's 2am-09am UK Local!

[Harry]

To be fair, I don't remember there being that much confidence this morning! This was always going to be a bit of a knife edge scenario - with fairly high confidence over rainfall, less so in respect of severe/convective weather.

The low is pretty much on track - but there's just little confidence as to whether it will produce thunderstorms (or better an MCS), frontal heavy rain with occasional thunder, or just rain which is occasionally heavy and not electrified. The low en route has been responsible for triggering big thunderstorms including numerous MCS on its track north from Spain/Portugal. As for guessing what it'll do in the coming hours is causing a lot of raised eyebrows and question marks.

Rain showers and thunderstorm rain for Heathrow EGLL 221115Z 2212/2318 07005KT CAVOK TEMPO 2301/2308 7000 SHRA TSRA

Between 01 and 08z tomorrow that's 2am-09am UK Local!

Sounds good to me

[staplehurst]

MetO reverted back to "heavy rain, thundery at times with local downpours possible"

Confidence is really not all there across the board.....

Different forecasters, different opinions

GFS looks pants to say the least!

I'm not following the GFS, it really hasn't dealt well with the past few days and I don't think it represents tonight's events very well either...

Edited August 22, 2011 by staplehurst

[Harry]

Different forecasters, different opinions

I'm not following the GFS, it really hasn't dealt well with the past few days and I don't think it represents tonight's events very well either...

Very true - it totally missed this morning's monster MCS!

[Robbie Garrett]

Sounds good to me

TAF Updates soon, I'll see if it's a PROBABILITY or a 100% likely to happen, at the moment it's a 100% of a temporary change from CAVOK (Clouds and VIS OK) with a PROB30 of HEAVY Thunderstorm in Rain, but saying this those storms we had on the 27th June, that was a PROB30, with no 100% likely.

EGLL 221115Z 2212/2318 07005KT CAVOK TEMPO 2301/2308 7000 SHRA TSRA PROB30 TEMPO 2302/2308 3000 +SHRA +TSRA BECMG 2304/2307 5000 BR -DZ SCT007 BKN010 TEMPO 2306/2312

[Staffordshire]

Hey guys, just got back from seeing the relatives down in Chichester. Just wondering if I am missing anything coming back today or should I have stayed longer? Oh and did Lichfield get anything over the weekend, is there a website where I can view radar outputs for satarday,

[Harry]

UKASF update

Central, Southern and South-East England

Synopsis:

A complex synoptic pattern is forecast during Tuesday as frontal systems associated with a convective area of low pressure drift northwards out of France and affect many Central, Southern and South-eastern areas of England during the day. Increasingly cyclonic conditions are expected further north and west with some scattered showers and perhaps longer spells??? of more frontal rain across Ireland later, despite some reasonable drier and brighter conditions at times.

Discussion:

A highly complex mixture of both dynamic and convective precipitation is expected to push northwards out of France this evening in association with the surface low pressure which is forecast to drift northwards, as highlighted above, overnight and through Tuesday. The primary threat of convective activity may well occur during the overnight period tonight and through into the early hours of Tuesday morning.

The threat of thunderstorms exists in association with some extreme instability over in Northern France which is associated with the surface low pressure. Frontal zones are likely to act as primary sources of more dynamic and persistent precipitation, but the convective nature of the low pressure is likely to bring a threat of some heavy and thundery showers northwards out of France, across the English Channel and into southern areas of England overnight. DLS (0-6KM) and helicity across Northern France is of significant levels, with a significant threat of well organised multicellular thunderstorms and perhaps even an MCS. These well developed environmental conditions for organised thunderstorm activity is likely to be a primary reason why heavy and thundery showers are likely to traverse the English Channel and affect parts of the south overnight.

It is prudent to add that this kind of synoptic setup is notorious fickle and extremely difficult to forecast. As if often the case the lack of surface heating over the English Channel usually signals some weakening or total dissipation of thunderstorm activity. However, with a marked, albeit small, trough associated with the surface low pressure leading to a region of DPVA there is once again further evidence to support some well organised thunderstorms moving across the English Channel and affecting southern areas overnight.

A general region of heavy rain, showers and thunderstorms early on Tuesday is likely across the region highlighted. As the day progresses the convective risk is likely to reduce and any heavy precipitation is forecast to gradually clear away out into the North Sea. At the moment the primary risk of severe weather is from frequent lightning activity and torrential downpours leading to localised flooding. The severe thunderstorm threat, with a risk of large hail, severe wind gusts and tornadoes, is forecast to remain over in the near continent with the majority of the forecast models keeping the severe DLS and helicity values again over in France.

Depending on how the remainder of the evening develops, it may well be prudent to upgrade theSLIGHT risk to a MODERATE risk, but for the time being given the highly complex nature of the synoptic setup a SLIGHT risk will suffice

More promising IMO!

Satellite imagery continues to show the LP spawning more thunderstorm cells too

[Robbie Garrett]

Furthermore, Area D (London/East Anglia and South East) Occlusion and Warm Fronts moving North North East at 20knots with the Fronts overhead south downs or so at - Ocasional 7km visibility in Showers of Rain With TSRA (Thunderstorm In Rain) in area D1 is a cold front moving East at 10knots) (English Channel and France) and MAINLY FRONTS.

So in English, best of the weather will be the South East, however most likely France/English Channel according to MetOffice Aviation.