Storm & Convective Discussion - 01/03/15 onwards

[IanR]

Convection a bit flatter today and change in cloud direction

Edited May 1, 2015 by IanR

[IanR]

Did an overnight timelapse and caught my first lightning flash for 2015 at around 30s or 1.20am. The flash was to the north, somewhere over Lancashire.

that was very me, my friend heard the thunder, he said only one rumble,  I was asleep   ,  and one bolt does not make a storm ,  *off back to the NSC*  

[Thunderbolt_]

Hmm yes, interestingly enough the BBC are giving me a forecast for thunder on Sunday, and they've been saying this for a couple of days now. Certainly one to watch...

 

[IanR]

there was a little thundery activity over this area a couple of nights ago during the early hours 

[NorthYorksWeather]

Some pockets of decent SB cape tomorrow afternoon/evening. 

 

One to keep an eye on, especially for tornado alley (Lincolnshire and East Yorkshire)

[cheese]

Yeah I'm actually looking forward to tomorrow - after the rain has cleared in the afternoon temperatures will rise to 16C, accompanied by dews of 11-13C, so will be the first proper  humid feeling day of the year. Let's wait and see.

[Nick F]

 

THERE IS A RISK OF THUNDERSTORMS FORECAST

 

Valid: 03/05/2015 0600z to 04/05/2015 0600z

 

Synopsis

 

Upper trough will reside to the west of the British Isles on Sunday, with a slow-moving surface low pressure area to the NW of Ireland. Sets of weather fronts will move NE across UK and EIRE in the morning bringing bands of rain, followed by brighter but showery SWly flow.

 

... EIRE, N IRELAND, THE MIDLANDS, SERN, ERN and N. ENGLAND, S SCOTLAND ...

 

Increasingly colder air in the mid-levels will overspread moist post frontal SWly flow at the surface ... which, combined with surface heating, will create increasingly steep lapse rates across central and southern UK and Ireland. The increasingly unstable airmass in wake of frontal rain moving NE in the morning will support development of heavy showers and isolated thunderstorms with surface heating. Increasingly diffluent flow aloft with approaching left exit region of SWly jet streak over Nern France and some 30-40 knts of deep layer shear may help organise any storms that develop over Sern/Ern England and The Midlands, with a risk of hail, localised flooding and strong wind gusts the main threat ... though the risk of severe weather appears too low (less than 5%) to warrant a Marginal risk.

 

issued by Nick Finnis

[Lauren]

Forecast for thunder on Tuesday. I'm going to take that with a truckload of salt.

[Flash bang flash bang etc]

Dunno about today (lots of stubborn cloud here) - but tomo night seems like a good bet for something. My money is on that but will have my camera handy today all the same ;-)

[Supacell]

GFS is still developing showers and an area of slight CAPE in the post frontal warm airmass across the Midlands into Lincolnshire and East Anglia this afternoon. It is fairly early on with the best chances being through the afternoon, drying out through the evening, although showers continue to pepper western areas. If GFS is on the mark then the southern portion of this CAPE could benefit from around 20 knots of deep layer shear which could help organise any showers or storms that do form. It is a low risk and dependent on some sunshine breaking through, without the sunshine I do not see any storms. 

 

The Met Office, BBC and Euro4 all show showers breaking out somewhat later from mid afternoon through to the evening in pretty much the same places as the GFS. A more pronounced area of showers develops in a line from around Cardiff to the Wash on Euro4. 

 

Overall I think there is a chance today for anyone across the Central slice of the country to get some heavy showers and maybe a weak storm - Midlands/Lincolnshire/EA. A stronger storm may develop across the SE Midlands and move into East Anglia.

 

Tomorrow night sees an area of heavy rain move up from France on what will have been a day of big thunderstorms for them. There is the chance that some of this thundery activity could clip the SE and far east of East Anglia, giving the risk of some overnight thunderstorms. This is subject to change though, any shift east would keep the thundery stuff over the Continent, something we in the UK have become very accustomed to. A shift west and more of us could see something thundery.

[BrickFielder]

Different models not entirely in agreement about the potential today, except perhaps that there is a risk of storms developing in east Anglia late in the afternoon. Lincolnshire and Norfolk late afternoon appear to be prime locations for potential.

Mid level lapse rates are not stunning but seem enough to give storm potential. (26 degrees difference typically needed for a storm but above 30 is ideal, so 28 is within the realms of possibility)

Triggering for storm potential is a bit more tricky. There is some post frontal vorticity which declines as the front moves away , there is not much in the way of on shore winds , little I the way of low level wind convergence and slim evidence of orographic lifting (effect of hills and mountains) playing a part. What I think we are left with is some questionable low level convergence.

If they do materialise then netweathers NMM model shows some interesting mid level vorticity as a result of developing storms.

With model agreement tricky it is hard to pinpoint today.

There does appear to be low level wind speed shear today so a strong updraft could pick up low level vorticity. Directional sheer through out looks poor which generally speaking you would see from a marked tornado risk. Storms can and do make their own environments and that is what I think the NMM mid level vorticity charts are suggesting today (You could get a surprise). Since temperatures are not that high today, lapse rates are not outstanding, and instability is not the high the risks of a severe storm today are pretty low.  Key areas would be eastern England late afternoon and perhaps a line just north of the M4 corridor.

 

[Mapantz]

The NMM 3 model (which I can't show here) has the shower activity in Wales and the Southwest bang on! It shows activity dissipating until later this afternoon ,when it rears up again, similar to what the NMM 4 shows. As Brickfielder mentions, there is a fair bit of disagreement across the low res models, as there was with last nights frontal rain. It'll be interesting to see how this pans out?!

Edited May 3, 2015 by Mapantz

[Harry]

GFS is still developing showers and an area of slight CAPE in the post frontal warm airmass across the Midlands into Lincolnshire and East Anglia this afternoon. It is fairly early on with the best chances being through the afternoon, drying out through the evening, although showers continue to pepper western areas. If GFS is on the mark then the southern portion of this CAPE could benefit from around 20 knots of deep layer shear which could help organise any showers or storms that do form. It is a low risk and dependent on some sunshine breaking through, without the sunshine I do not see any storms. 

 

The Met Office, BBC and Euro4 all show showers breaking out somewhat later from mid afternoon through to the evening in pretty much the same places as the GFS. A more pronounced area of showers develops in a line from around Cardiff to the Wash on Euro4. 

 

Overall I think there is a chance today for anyone across the Central slice of the country to get some heavy showers and maybe a weak storm - Midlands/Lincolnshire/EA. A stronger storm may develop across the SE Midlands and move into East Anglia.

 

Tomorrow night sees an area of heavy rain move up from France on what will have been a day of big thunderstorms for them. There is the chance that some of this thundery activity could clip the SE and far east of East Anglia, giving the risk of some overnight thunderstorms. This is subject to change though, any shift east would keep the thundery stuff over the Continent, something we in the UK have become very accustomed to. A shift west and more of us could see something thundery.

 

Agreed - an exciting couple of days coming up.

I think supacell has hit the nail on the head for the best chance of storms today, any where from the Bristol Channel to the Wash seems best located, perhaps 20-25 miles or so south of that line and may 100 miles or so towards the N/NE of that line. I think the southern counties will probably miss most of the action today, though the sun has been glimpsing through the cloud this morning and it is a very warm and humid (feeling) airmass. 

 

Tomorrow looks a corker of a day in terms of warmth and sunshine, with the breeze increasingly steaming in from the south during the afternoon. While I am a little tickled with excitement over tomorrow night's prospects (given my thunder count for 2015 currently stands at NIL), in my experience early May is too early for imports and I, at this stage, predict while some no doubt heavy rain will trundle northwards with maybe the odd spark,  I expect electrical activity to follow the French coast and into Belgium (if any), perhaps scraping the Kent/Sussex coast at best. I know its a little bit pessimistic, but in my experience perfectly realistic for this time of year.

[chapmanslade]

Big showers now forming along the SW peninsula and moving NE passing through here

[East_England_Stormchaser91]

Sun is full on out now and the ground rapidly drying out from this mornings rain.

Promising signs so far!

[Paul]

Today could be a decent day to use our free storm radar apps

 

Android:

https://play.google.com/store/apps/details?id=com.netweather.stormradar&hl=en_GB

 

iOS

https://itunes.apple.com/us/app/netweather-storm-radar/id976072666?ls=1&mt=8

[Ǝssex Ǝasterly]

First few strikes appearing now SE of Chippenham 

[A.J]

First few strikes appearing now SE of Chippenham 

yep, thunderstorm to the south of Devizes, around 15 miles from me

[BlueHedgehog074]

A dark, very heavy, shower just passing by to the South of here in Solihull and heading towards Coventry/Nothern Coventry. Netweather radar shows some red and dark red spots in it, so possibly some hail contained within the shower.

Edited May 3, 2015 by DiagonalRedLine

[Thunderbolt_]

A dark, very heavy, shower just passing by to the South of here in Solihull and heading towards Coventry/Nothern Coventry. Radar shows some red and dark red spots in it, so possibly some hail contained within the shower.

 

Very nice clouds there. It looks like you're iin quite a good spot today. I'm not expecting too much up here, unless the clouds break ths afternoon, but you never know.

[gottolovethisweather]

I can see a tasty ole storm out West right now, should hit Newbury/Andover area within next fifteen minutes or so, likely to produce first sferics and Thunder of the season for me.

 

EDIT: more likely the worst of the showery outbreak will hit A34 region North of Newbury towards Oxford region, very shortly.

Edited May 3, 2015 by gottolovethisweather

[BlueHedgehog074]

Very nice clouds there. It looks like you're iin quite a good spot today. I'm not expecting too much up here, unless the clouds break ths afternoon, but you never know.

Thanks Scott. Looks like something could happen here shortly (although no thunder heard from any of the showers to my South-West and South yet). Does seem to mostly a Wales, Midlands and Eastern UK event today, though. But hopefully perhaps if some sunshine does start breaking through where you are, then maybe something thundery could still happen for you.

[Harry]

Sun finally coming out here...whoop!

 

Certainly the distribution of the convective activity currently in line with charts posted earlier by BF. The fact there is activity further south obviously pleases me...to see some nice Cb structures rolling north would please me in all honesty...not seen an anvil for probably nearing 6 months now

Edited May 3, 2015 by Harry

[A.J]

nice line of showers/storms drifting up across the west country...I might well hear a rumble or two in the next hour or two

[Supacell]

I am all set and ready to chase now on what looks like being the first proper convective day of the season. I am hoping that more storms can develop a bit further north.