Convective Outlook

[Harry]

Yes, certainly best chances seem reserved for Southern and Southeastern parts on Saturday/Sunday.

.........................................................for now!

Let's not begrudge us either people - we've had virtually nothing, either in actuality nor forecast! That's two Mays now (09 and 2010) where I haven't heard a single rumble, seen a single flash or even seen a decent looking Cb (excluding the USA)

[Thundery wintry showers]

Still too far off to put any meat on the bones, but better prospects than were showing yesterday. Next week looks quite convective across whole of the UK as low pressure moves in.

Yes indeed, critical IMO is the slacker low pressure and weaker-looking jet which allows a more prolonged breakdown of the HP and then a more showery (as opposed to dull & wet) outlook when the low gets in.

How typical all the fun looks reserved for the East again. <_<

Not necessarily. GFS 06Z suggests storms moving up the western side on the 6th June- by no means guaranteed, but in a southerly flow that kind of thing sometimes happens, with thunderstorms rumbling their way up central and western areas to the east of an approaching cold front.

Precipitation is surprisingly lacking over East Anglia and SE England on the 06Z but of course this may change on subsequent runs given that it's still a fair range out.

[Supacell]

06z different to the 00z in that the main activity now looks further west. But as TWS says, too far out yet.

A chance to of some thundery showers breaking out across the Pennines on Sat evening, which would be good for me <_<

[Stuart]

did i hear word on bbc news 24 about thunder risk but there did not say were

Edited June 3, 2010 by Stuart

[Nick F]

Probably need to wait until we are within the t+48 range, i.e. tomorrow morning's runs, to get a better idea of where storms may develop over the weekend. Meso models such as those from UKMO and NAE only go out to the t+36-48 range, and these tend to be the best at modelling where storms may develop and meso features such as a MCS.

[Stuart]

my best guest is from the borders down to the midlands. well i hopeing

[NorthNorfolkWeather]

I can only hope that the lack of anything substantial so far this season, means we are 'stocking up' electrical energy for a big storm soon!!!!

That sounds like my Gran, who, in the 70's during the 3 day week when we had rolling Power cuts, would turn off the lights when the power was on 'To save it for later" :-)

[Costa Del Fal]

Not necessarily. GFS 06Z suggests storms moving up the western side on the 6th June- by no means guaranteed, but in a southerly flow that kind of thing sometimes happens, with thunderstorms rumbling their way up central and western areas to the east of an approaching cold front.

Precipitation is surprisingly lacking over East Anglia and SE England on the 06Z but of course this may change on subsequent runs given that it's still a fair range out.

Would these be elevated in Nature???

Does look interesting on the GFS with some really heavy rain with it but im sure it will keep chopping and changing for a bit yet.

[BrickFielder]

At the moment I am not convinced of the thunderstorm potential for Friday, Saturday and Sunday, but I am considering next tuesday. The reason is the 850-500hPa lapse rates.

It is not very often you get a thunderstorm with 850-500hPa lapse rates below 25C.

Looking at forecast SkewT's it just might be possible to get a storm on Sunday providing surface temperatures sneak a little higher and dewpoints are up a little.

Then we must consider what the forcing mechanism will be (fax charts currently suggest low over south east) and whether cloud cover from residual storms over France will play a part. So too early to tell from my point of view, but some potential here.

As for Tuesday then I prefer the lapse rates and the fact that we have a slack low pressure overhead. Yet again I am not convinced by the forcing mechanism shown currently by GFS. I would perhaps expect an occulsion spiralling out from a low pressure as the fax charts show.Forecast SkewT's suggest modest instability, but notice that surface temperatures are down from Sunday and there is moisture all the way up meaning storms may not be that strong.

Still its a bit more interesting than having no potential.

[Coast]

Still its a bit more interesting than having no potential.

Thank you for that Brick, good to see you in here today (that in itself is a positive sign that the season might be getting underway!!!! )

[Nick F]

Looking at forecast SkewT's it just might be possible to get a storm on Sunday providing surface temperatures sneak a little higher and dewpoints are up a little.

Then we must consider what the forcing mechanism will be (fax charts currently suggest low over south east) and whether cloud cover from residual storms over France will play a part. So too early to tell from my point of view, but some potential here.

I suspect any storms that develop at the weekend will be associated with warm moist plume (with high theta-e values) advecting north out of France ahead of Atlantic trough to the west, and that elevated storms will develop above a stable boundary layer, so surface temps and dew points may not be an issue for storm development provided mid-levels become unstable as upper trough to the west destabilises the plume aloft. Also, storms may develop over hills/mountains of the west with help of orographic forcing.

As for Tuesday then I prefer the lapse rates and the fact that we have a slack low pressure overhead. Yet again I am not convinced by the forcing mechanism shown currently by GFS. I would perhaps expect an occulsion spiralling out from a low pressure as the fax charts show.Forecast SkewT's suggest modest instability, but notice that surface temperatures are down from Sunday and there is moisture all the way up meaning storms may not be that strong.

think it's too far off to go into specifics of forcing mechanisms, though there will be plenty of diurnal convective activity by the looks of it next week, some it surface based.

[ZONE 51]

Saturday night into Sunday morning looks potentially interesting, with a thundery trough developing across SE UK as warm moist theta-w plume axis advects north out of France across the SE corner with strengthening southerly upper flow. Storms could develop in plume axis.

This morning's fax charts show a developing cold front at Sun 00z (shown by triangles with dots between) marking the western edge of the warm moist plume, this then shifting east by 12z:

Still too far off to put any meat on the bones, but better prospects than were showing yesterday. Next week looks quite convective across whole of the UK as low pressure moves in.

its time to get those cameras set for saturday night im so sure the SE is in for a fantastic display

i just love these hot clear days. then the build up to potential storms!

Edited June 3, 2010 by nimbilus

[Harry]

its time to get those cameras set for saturday night im so sure the SE is in for a fantastic display

i just love the hot clear days and the build up to potential storms!

Apologies if I've misunderstood your post nimbilus, but certainly in recent memory plume thunderstorms, particularly imports, are preceded by generally hazy and murky skies, as both the anvils race over us quite early on ahead of any arriving storms, plus should there be mid level instability as I'd associate with this type of set up, the development of Altocumulus (specifically Altocumulus Castellanus - oh yeah!) throughout the afternoon period.

If the skies were clear and sunny (like today and yesterday which have been glorious!!) I'd probably be concerned...but to be honest that's just based on my quite limited experience watching storms.

All of which is an aside really - looking at the latest GFS run, with the exception of maybe one or two home grown storms of which the consensus is are likely to be weak, I cannot see us getting any imported stuff from France, with even eastern most Kent missing out on this occasion (surprise surprise!!) - I still think 4 days out is too far in advance though to take GFS seriously - with hints that the breakdown from the West could be slower, GFS may be overcooking the breakdown and wrongly keeping it just to our East... until late tomorrow and into Saturday, I wouldn't take the charts, especially GFS, too seriously at this stage.

Edited June 3, 2010 by Harry

[ZONE 51]

Apologies if I've misunderstood your post nimbilus, but certainly in recent memory plume thunderstorms, particularly imports, are preceded by generally hazy and murky skies, as both the anvils race over us quite early on ahead of any arriving storms, plus should there be mid level instability as I'd associate with this type of set up, the development of Altocumulus (specifically Altocumulus Castellanus - oh yeah!) throughout the afternoon period.

If the skies were clear and sunny (like today and yesterday which have been glorious!!) I'd probably be concerned...but to be honest that's just based on my quite limited experience watching storms.

sorry i wrote it wrong harry , yes of course the skys preceding storms especially imports would occur , i look out for altocumulus floccus to as this is my fav Edited June 3, 2010 by nimbilus

[Harry]

sorry i wrote it wrong harry , yes of course the skys preceding storms especially imports would occur , i look out for altocumulus floccus to as this is my fav

Ah ok cool - if I remember correctly, the 'mackerel sky'...indeed, one of my faves too

[Costa Del Fal]

GFS 12Z (although not loading on NW for me so using Wetterzentrale) still shows an area of very heavy precip moving into SW England, Wales, West Mids, Northern England through Sunday. Thundery potential perhaps as the charts show the rain developing in the Bay of Biscay area all of a sudden.

[Guest FireStorm]

I Truly love elevated storms for the evening and overnight. Can sit in the garden watching the IC dancing away merrily in the cloud tops!! Saw my 1st proper elevated storm with IC and no thunder, no rain, and no wind at all to speak of a number of years ago and was in total awe. I pray I see many more like it

[Mesoscale]

BBC weather just put that t word back into there sunday forecast!

fingers crossed for a couple of imports to come over from france

[The PIT]

GFS 12Z (although not loading on NW for me so using Wetterzentrale) still shows an area of very heavy precip moving into SW England, Wales, West Mids, Northern England through Sunday. Thundery potential perhaps as the charts show the rain developing in the Bay of Biscay area all of a sudden.

This evening forecast had that out in the eastern areas and edging into the north sea.

[Costa Del Fal]

This evening forecast had that out in the eastern areas and edging into the north sea.

The GFS likes to disagree.

[Costa Del Fal]

Interesting FAX output this afternoon with regards to Sunday's storm potential- developing cold front and trough further west than on previous output, with low centred towards the south-east. Certainly some scope for thunderstorms late afternoon to evening period on Sunday across a few parts of the country.

Very good but still scope for Change. GFS has it even further West but interesting nevertheless to see the Fax move it West too.

[Stormyking]

You know the latest 12z for saturday evening into sunday, i noticed theres a alot of heavy rain too coming up from fracne or Bay of Biscay, anyone know if here along South coast we may see some thunder and lightning, I know it is still 2 days off but it has got me interested.

[Rob]

You know the latest 12z for saturday evening into sunday, i noticed theres a alot of heavy rain too coming up from fracne or Bay of Biscay, anyone know if here along South coast we may see some thunder and lightning, I know it is still 2 days off but it has got me interested.

the potential is there, but at this stage impossible to say really, keep an eye on the charts over the next day.

[Costa Del Fal]

You know the latest 12z for saturday evening into sunday, i noticed theres a alot of heavy rain too coming up from fracne or Bay of Biscay, anyone know if here along South coast we may see some thunder and lightning, I know it is still 2 days off but it has got me interested.

There is this could be thundery (elevated in nature) however id wait till tomorrow evening at the earliest to say really. Positioning is still open to question though at the moment most charts seem to have moved it West from this morning when it was shown to be in the East.

[Ian Fergusson]

There is this could be thundery (elevated in nature) however id wait till tomorrow evening at the earliest to say really. Positioning is still open to question though at the moment most charts seem to have moved it West from this morning when it was shown to be in the East.

Agreed. UKMO-GM also yet to be convinced on the E-W positioning (sizeable error margin) and a more westerly bias for plume engagement wholly plausible. We'll await the next runs with interest. Timing of the breakdown also open to major uncertainty (Saturday evening onwards seems a reasoned punt for some districts...stress 'some')