UK Convective General Discussion & Forecasts - May Into June 2012

[Lewis]

Storm from the other month, larger picture to that in my signature, more of this please tomorrow ;

[Jane Louise]

Good luck for tomorrow all Maybe more of a chance for most of us tomorrow now we are in the month of June. I know June is starting off on a not so good note! but it looks like it's warming up after a couple of weeks of dull weather . Maybe a good sign for the start of our summer thunderstorms .

[Jane Louise]

8.55pm Tues

Moderate Risk of Scattered Thundery Showers Ireland & UK 09Z-21Z

Stronger Organised Convection Possible (as per yellow box)

Irregularities between models now much less obvious. GFS, NMM and WRF now pretty firm on the potential for a widespread thundery regime through Weds, Hence a Moderate Risk level is more appropriate!

An unstable environment builds within the post frontal sector. A number of surface troughs expected to develop from quite early on Weds morning. Relatively weak upper trough nudges eastward increasing lift with a number of moderate strength PVA Max's looking to further increase lift along the northern periphery of the upper jet stream. Some marginal overlay of vertical shear to instability looks to take place for southern UK as per yellow box. Though based on the forecast vertical wind profiles I do not ATM see this support developing supercell characteristics on any storm building in this sector (though this could change)! Whilst Deep Layer Shear would appear strong, the vertical velocities are not showing cloud tops reaching this level. This will means that any building storm cell will be unlikely to tap into this strong upper motion. Lack of convergence right across the board and the low level shear looks rather weak ATM with fairly straight lined winds at all levels. So not ready to suggest any risk of tornado development. Though this cannot be entirely ruled out.

Prime regions where lightning could be more prolific might be around W.Midlands later in the day. Also likely to be a risk of strong gusts (non severe). Confidence is fairly good for results ATM. Certainly worth a heads up and requires careful monitoring.

It would only take some minor changes within the models to increase the severe aspect of this outlook.

This post has been edited by Tony Gilbert: 05 June 2012 - 21:19

http://www.ukweather...-6th-june-2012/

[Lewis]

8.55pm Tues

Moderate Risk of Scattered Thundery Showers Ireland & UK 09Z-21Z

Stronger Organised Convection Possible (as per yellow box)

Irregularities between models now much less obvious. GFS, NMM and WRF now pretty firm on the potential for a widespread thundery regime through Weds, Hence a Moderate Risk level is more appropriate!

An unstable environment builds within the post frontal sector. A number of surface troughs expected to develop from quite early on Weds morning. Relatively weak upper trough nudges eastward increasing lift with a number of moderate strength PVA Max's looking to further increase lift along the northern periphery of the upper jet stream. Some marginal overlay of vertical shear to instability looks to take place for southern UK as per yellow box. Though based on the forecast vertical wind profiles I do not ATM see this support developing supercell characteristics on any storm building in this sector (though this could change)! Whilst Deep Layer Shear would appear strong, the vertical velocities are not showing cloud tops reaching this level. This will means that any building storm cell will be unlikely to tap into this strong upper motion. Lack of convergence right across the board and the low level shear looks rather weak ATM with fairly straight lined winds at all levels. So not ready to suggest any risk of tornado development. Though this cannot be entirely ruled out.

Prime regions where lightning could be more prolific might be around W.Midlands later in the day. Also likely to be a risk of strong gusts (non severe). Confidence is fairly good for results ATM. Certainly worth a heads up and requires careful monitoring.

It would only take some minor changes within the models to increase the severe aspect of this outlook.

This post has been edited by Tony Gilbert: 05 June 2012 - 21:19

http://www.ukweather...-6th-june-2012/

Interesting he goes for West Midlands, when all models clearly show it's East Mids, SE, Lincs and Yorkshire (Eastern areas)

[Costa Del Fal]

"Prime regions where lightning could be more prolific might be around W.Midlands later in the day. Also likely to be a risk of strong gusts (non severe). Confidence is fairly good for results ATM. Certainly worth a heads up and requires careful monitoring. "

Lets hope so as its about damn time we had something here. Still waiting for my first storm of the year!

[BornFromTheVoid]

A thunderstorm's down burst caused this in Ireland a few hours ago.

http://www.rte.ie/ne...y-flooding.html

[Chris.R]

some lowd sferics on the radio atm, sound quite close but can't hear any thunder or see any lightning though

[Chris.R]

moderate showers here now, getting progressively heavier. Looking interesting

[Lynxus]

Right.

As estofex hasnt got any info today I suppose ill have to go hunting the models.

Google & Netweather have had a lightning symbol over my location all week. So fingers crossed.

Im sure it will change at the last moment.

Not much in the way of "convergence" so I can only assume its unstable air already.

[VillagePlank]

Looking good ... skew-T's for Heathrow,

Showers will form in a moderately (first time this year I've used that word) convective environment; some of those showers will be severe, but only one or two and only in favoured areas such as those with the added benefit of orographic lift. Local flooding is a real risk around lunchtime.

Surface heating is in play today, as well as other mesoscale features: a complex scenario, but one that, I think, will produce at least thundery showers, and some thunderstorms.

Best time is early afternoon, the show is over by evening.

Edited June 6, 2012 by Boar Wrinklestorm

[Coast]

Morning all!

Sorry, a lack of early morning internet causing a 'Coast outage'

Surprisingly none of the dedicated sites have anything about storm forecasts for today, I guess that's down to manpower during this holiday period, rather than a drought of potential action?

Here's a few charts and data that might give us a clue if anything is on it's way:

21st OWS show something over Scotland and the beginnings of something in the Channel straights:

Strong possibility of lightning almost anywhere today according to the AFWA ensembles:

GFS has it starting on the SW coast around midday:

Then BAM!!!! right through the middle of the country later:

Nice bit of CAPE lurking there:

Convergence running West to East through the Midlands and 100 miles or so either side:

Here that border which seems to form the centreline of interest:

SBCAPE through the middle of the Country all the way from Wales to the East coast:

and a very interesting area of tornado chances in this blue edged area:

Helicity out over Lincolnshire and East Anglia:

A generally quite interesting day I would have thought???

If we can get some heat into things..........

[Robbie Garrett]

I will be heading to Heathrow today, hopefully I am in the usual firing line that's Heathrow Airport.

[Coast]

I will be keeping an eye on this wave through the day:

Might get a few hefty hail showers mixed in there?

[VillagePlank]

CAPE is certainly high enough to produce a hail risk. T/storms are possible almost anyway, today. Defo a radar watching day.

Edited June 6, 2012 by Boar Wrinklestorm

[MP-R]

Some huge downpours over southwest England at the moment - anyone down Exeter way reporting thunder?

[Lewis]

Have towers building quite rapidly here in East Hull.

The NMM runs from yesterday was suggesting a lot of cloud cover, certainly not the case up to now, although cloud cover is increasing slightly.

NMM continues to show massive cape and LI values, with cape around the 900-1100 values with a lifted index of -4, there is sufficient energy across this part of the region until sun down.

Looking like an interesting day.

Lewis

Edited June 6, 2012 by Storm Force Lewis

[wimblettben]

It is more like persistent rain here at the moment with no breaks in the cloud.

No thunder to report here yet.

[Methuselah]

Plenty of convection going-on here...

[Coast]

[BrickFielder]

I looked out the window this morning and saw a low cloud base with low clouds fairly zipping along. My first thoughts were that this was typical post frontal weather with a modicum of low level horizontal vorticity. While I think this will back off during the day it made me think of that low level vorticity as a potential source for tornadoes.

Looking at forecast charts for mid level winds however looked more uniform in strength which suggests super cell development ought to be off the cards today. Forecast SkewT's show a marked warming at around the 400hpa level moving up from the south which will limit cloud tops. Combine poor surface temperatures (meaning weak low level updraft strengths) and chances of tornado development looks extremely meagre.

What I do like is the potential lapse rates through the mid levels which should create some moderate instability.

We do have two potential surface wind convergence points today. A weak one around the bristol area and a more pronounced one around the Liverpool/Manchester area. With the trough bringing in moisture across the UK these could be good areas for convection initiation.

Vorticity charts show a mixed picture with the 700hpa charts suggesting positive vorticity advection for Ireland , Wales and parts of the south midlands early on, shifting through to east anglia, north midlands and the Liverpool to Hull corridor.

500hpa vorticity charts show positive vorticity advection (approaching vorticity) through the west midlands and an area moving into east anglia.

Key for me today is the potential cloud top height and where the tropopause is highest.

The zero degree isotherm is moderately low for this time of year and lift through that region could be relatively strong. This suggests some potential for hail and lightning. Overall the highest risk place of seeing a storm is likely to be southern Ireland, with perhaps a risk for east anglia and parts of midlands following. Late afternoon then I think Liverpool , Manchester across to Hull may see an isolated storm. I should note that some models do not rate the convective potential today, seeing at most a few heavy showers. Again I don't think its going to be a classic storm day with temperatures on the low side, low level winds a touch to brisk and mid to upper level conditions not ideal.

In summary, I am not sure what will happen and you are best just enjoying the radar watching or whatever comes your way.

[syncmaster]

cloud on the increase now in this neck of the woods as lewis says, sun out and temps creeping up, feels humid today....clouds certainly getting some height to them.

feel a drive out coming on later lol,,,,

16c and just having a sun shower,,,,,

Edited June 6, 2012 by syncmaster

[I Cumbria Marra I]

heard thunder at 5 am this morning!

[Chris.R]

Did I just see the word Liverpool? OMG!! Also now I know where those sferics were at 5 this morning.

[tara303]

Just gone dark, winds up and heavy rain - !!!!

[Costa Del Fal]

A lot of murky grey cloud out there today. Could significantly hamper things but lets hope it shifts.