Convective / Storm Chat And Discussion

[Lauren]

It's suddenly got very windy here with strong gusts.

[tomp456]

today has been such a let down!

[camiscool]

Indeed the first storm potential for the south east and it didnt happen

[Guest]

The shower that I mentioned above was a great one. Clouds were moving all over the place, and I think I got a picture of some rotation, will upload off my phone tomorrow hopefully. No thunder unfortunately, but lots of torrential rain, great structures, and some nice visible hail cores as well. The only thing missing was the thunder really.

[NL]

Neil Bradshaw's webcam shows the shower clouds starting to creep onshore across Tyne and Wear:

http://www.southshie...27s_weather.htm

Got small hail off those showers, expected so much more....

[Coast]

A little surprised myself at the lack of thunder activity today

I was too. Although it looked increasingly like not being in my area, I thought further up the East coast would see something. Hey Ho!! that's nature!

Quiet again for a while now:

[Harry]

Earlier indications from GFS of some heat and moisture flirting with us later this week.

CAPE/LI figures to die for over the continent (as ever from GFS a week in advance)

Something to talk about in the coming days at least

[Lauren]

It's all gone quiet for the UK!

[Coast]

It's all gone quiet for the UK!

Owww, still plenty of time to whip up a storm this year. I think the relatively early start and the fact that the recent one was quite a belter, has whetted peoples appetites - but I'm afraid this is a waiting game!

[Harry]

It's all gone quiet for the UK!

Not IF the 6z GFS verifies for around 5-6 days time

[Lauren]

Not IF the 6z GFS verifies for around 5-6 days time

You do I have no idea what that means don't you?

Explain in simpleton language please

[Harry]

You do I have no idea what that means don't you?

Explain in simpleton language please

Lol...

GFS is currently showing very high levels of CAPE/very low LI values across the continent and to a lesser extent, spilling into SE England over the coming weekend. My big 'IF' centres on GFS' ability to vastly over-egg CAPE/LI figures 5+ days in advance, therefore I am expecting a fairly big reduction nearer the time (providing the predicted pattern remains similar)

06z indicates that these charts were generated based on data observed/calculated at around 6am this morning.

If a chart 'verifies' then it means it comes true.

The next charts will be based on data observed and/or calculated at noon today - denoted by '12z'

Hope that helps

[NL]

You do I have no idea what that means don't you?

Explain in simpleton language please

GFS Global Forecast System http://en.wikipedia.org/wiki/Global_Forecast_System and the 06z stands for 6am zulu or more commonly called GMT. http://wwp.greenwichmeantime.co.uk/info/zulu.htm

Hope that helps Lauren.

[Coast]

Loving that GFS chart, now if it could just suck the CAPE in across the Channel straight over Kent and Sussex - kaboom!

The GFS Meteogram also shows it remaining interesting this time next week (usual caveats apply):

The KO index, a measure of instability taken by comparing the values at low (1000 to 850 hPa) and mid (700 to 500 hPa) levels, looks favourable at this point too:

KO Index = blue lines with values. (S = >+6 = stable, L = < -6 = unstable).

Vertical motion forced by dynamical forcing at 500 hPa = zones in color (hPa/hour). Critical values KO:

> 6: no potential risk thunderstorms.

2-6: small potential risk for thunderstorms.

< 2: potential risk for thunderstorms.

Vertical motion: large negative values = strong ascent

Combination of both:

Stable KO region + negative motion = frontal zone. If the negative motion is positioned on a strong gradient in the KO indices between a stable and unstable zone: front is potentially unstable with risk for severe embedded thunderstorms

Unstable KO region + negative motion = active upper trough with risk severe thunderstorms

Unstable KO region without negative motion = air mass instability which may produce thunderstorms due to diurnal heating (mainly in the afternoon)

http://translate.google.co.uk/translate?hl=en&sl=de&u=http://www.wetter3.de/ko_index.html&ei=3DjRTeqmNouEhQekrYGPDQ&sa=X&oi=translate&ct=result&resnum=5&ved=0CD4Q7gEwBA&prev=/search%3Fq%3DKO%2Bindex%26hl%3Den%26prmd%3Divns

Yes, I know - all far too big to view!

[Harry]

Loving that GFS chart, now if it could just suck the CAPE in across the Channel straight over Kent and Sussex - kaboom!

The GFS Meteogram also shows it remaining interesting this time next week (usual caveats apply):

I hate those usual caveats

[Guest Kent-Weather]

I'll believe it on the day myself. Pretty to look at though. If only

[Jane Louise]

I have my fingers crossed that it all pans out for us. Still a bit of time to go yet though. So not getting my hopes up yet Lol

[Lauren]

Lol...

GFS is currently showing very high levels of CAPE/very low LI values across the continent and to a lesser extent, spilling into SE England over the coming weekend. My big 'IF' centres on GFS' ability to vastly over-egg CAPE/LI figures 5+ days in advance, therefore I am expecting a fairly big reduction nearer the time (providing the predicted pattern remains similar)

06z indicates that these charts were generated based on data observed/calculated at around 6am this morning.

If a chart 'verifies' then it means it comes true.

The next charts will be based on data observed and/or calculated at noon today - denoted by '12z'

Hope that helps

I understand now, it was manly the 06z that was confusing me. I already understand the CAPE/LI stuff.

GFS Global Forecast System http://en.wikipedia....Forecast_System and the 06z stands for 6am zulu or more commonly called GMT. http://wwp.greenwich...k/info/zulu.htm

Hope that helps Lauren.

Thanks also.

I can only hope that map comes true, it's only fair.

That is some serious storm potential on the continent!

[Supacell]

And what a difference a day makes!

Lets hope the 00z GFS is a blip as it shows any warm, thundery stuff remaining across Europe this weekend. (I haven't looked any further than early next week as it is basically pointless to).

[Mesoscale]

Id love to see my areas rainfull totals, seriously lacking any rain.... 06z looked good but come those models toy with us all the time there not acurate at this time scale.

I realy hope it holds together though.

EDIT: yeah just looked through GFS none of the good CAPE/LI comes our way for the foreseable future! haha I even saw the lifted index at 14 lol

Edited May 17, 2011 by Mesoscale

[Lauren]

I am currently doing a raindance AKA cleaning the windows.

It will therefore definitely rain the next 24 hours.

[Thundery wintry showers]

After a pretty convective start to May (albeit with some areas missing a large majority of the showers) we may well be sliding into a pretty mundane spell of weather with the NW-SE split bringing warm dry weather and variable cloud to the SE, and cloud and rain to the NW. That setup is always just one or two steps away from bringing us a Spanish plume, but it relies upon the jet slowing down, and at the moment it looks like it may be kicking into gear.

[Harry]

And what a difference a day makes!

Lets hope the 00z GFS is a blip as it shows any warm, thundery stuff remaining across Europe this weekend. (I haven't looked any further than early next week as it is basically pointless to).

Indeed - GFS is a fickle beast and requires the upmost care more than 3-5 days in advance.

But, having said that I am often encouraged when GFS reduces us 3-4 days in advance - it is certainly not outside the realms of possibility that it will spread back towards our shores. Our best storms have always been those which have appeared possible a day or two in advance as opposed to several days which seldom comes off.

If you compare the last two runs (12z and 06z), the 12z tries to edge the juice slowly back towards our shores.

The synoptics are somewhat variable to say the least...there is significant wiggling in the charts with regards the progression and development of Lows to our West. At the moment, weak ridging is always prevalent towards us in the South...strong enough to keep depressions at bay.

Thursday's charts will be more of interest IMO - I'd still take these, as those before, with a pinch of salt.

[A.J]

Indeed - GFS is a fickle beast and requires the upmost care more than 3-5 days in advance.

But, having said that I am often encouraged when GFS reduces us 3-4 days in advance - it is certainly not outside the realms of possibility that it will spread back towards our shores. Our best storms have always been those which have appeared possible a day or two in advance as opposed to several days which seldom comes off.

If you compare the last two runs (12z and 06z), the 12z tries to edge the juice slowly back towards our shores.

The synoptics are somewhat variable to say the least...there is significant wiggling in the charts with regards the progression and development of Lows to our West. At the moment, weak ridging is always prevalent towards us in the South...strong enough to keep depressions at bay.

Thursday's charts will be more of interest IMO - I'd still take these, as those before, with a pinch of salt.

Just a quick note Harry...from my understanding, it's probably best to compare like for like runs (ie yesterday's 12z and todays 12z as opposed to consecutive runs) as I believe from the winter model threads that the 4 daily runs each use different data sets....I think :unsure:

[Harry]

Just a quick note Harry...from my understanding, it's probably best to compare like for like runs (ie yesterday's 12z and todays 12z as opposed to consecutive runs) as I believe from the winter model threads that the 4 daily runs each use different data sets....I think :unsure:

Agreed - my lack of clarity always centres around which data set tends to be more accurate.

I remember reading some time ago that the 12z TENDS to verify more than the 06z (which is relatively promising) however I have no specific evidence to back that.