Uk Convective General Discussion & Forecasts, 20th June 2012>

[ardsar]

Best areas for this may be the South West initially and later London and Essex/Kent etc.... will be interesting if something can kick off Wednesday Night.

Guess i will miss them at home on Wednesday night as going upto Gatwick for a training day on Thursday. The drive home on Thursday could be interesting though.

Looking forward to the first real test of my boltek detector (website below). :-)

[Gael_Force]

Thanks Supacell for your info much appreciated,I'm not looking to drive around just looking to get myself in a good place to be if this event comes off,I'm looking at flying from Bristol to a location in France where storms could be quite active,so basically rather than looking for the storms be somewhere where they come to me.

Here is the 3 day outlook from the French orage specialist site, Keraunos. http://www.keraunos.org/prevision-orage-tornade-france-moyen-terme.html

I'm not sure if you read/speak French; if not, Google will do a passable job.

Regional radar http://www.meteo60.fr/radars_index-ouest.php

Real-time lightning for a small cost http://temps-reel.meteorage.fr/service_navigation.php

[AWD]

Storm Risk forecast for the next 5 days in Bristol

24/06 20%

25/06 11%

26/06 51%

27/06 80%

28/06 31%

How accurate are these things then?

Edited June 25, 2012 by Active Weather Dude

[Supacell]

I have to say, after planning long drives this week, i am thinking i would be better to stay close to home. A short drive NE may be all that is required if current outputs are correct

[P-M]

Top prize*, atm, looks like going to N and NE England going by current output- both GFS and ECM model thunderstorms dominating that region in general.

*rotating thunderstorms.

We're all still in the game, though.

I will bank that then from an IMBY perspective haha but seriously I agree that the drama and build up is fun even if we end up with nothing, although I am gutted when its a no show like....

[Harry]

Nope lol, but in that sort of situation you'd want an MCS

Nothing beats it!!

A yearly (sometimes several in one year) event in the 90s...they were the years

[mattyk1985]

Well I've booked Wednesday and Thursday off work so hopefully I havent wasted my holidays lol If it all kicks off though least I get to test out my new camera.

[Kain]

A yearly (sometimes several in one year) event in the 90s...they were the years

I can remember some cracking storms in the 90s. I can remember one, 1997 ish lasted all through the night! I can remember blagging a day off school the next day complaining I was tired staying up all night watching the thunder!

Truanting is wrong kids!

[Robbie Garrett]

A yearly (sometimes several in one year) event in the 90s...they were the years

I know, scared the ***t out of me those did.

RE: http://www.keraunos.org/prevision-orage-tornade-france-moyen-terme.html

Wednesday , the dorsal elevation will extend to the north, ensuring the continuation of an anticyclonic flow curvature. During the afternoon, a minimum dynamic will be positioned at the bottom of trough. At the same time, a strong pulse of mild and moist air in lower layers, characterized by values ​​of neighboring T'w 16 to 20 ° C at 850hPa, win areas stretching from the Pyrenees to northern- is. In fact, the vertical profiles will equip themselves with a strong instability in MUCAPE with values ​​generally between 800 and 1300 J / kg for MULI <-2K. In the absence of forcing structured, the risk should be limited to storm relief Pyrenees and Vosges. By late afternoon, some over premises shall not be excluded on the surrounding plains.These storms, such as single cell, can generate locally significant hail the Pyrenees (HCAPE> 750 J / kg).While the storm may disappear in the evening on the north-east, it will continue throughout the night on the edge of the Pyrenees Atlantiques, without showing any particular severity.

Thursday , the minimum altitude rapidly migrate from the Atlantic approaches to the British Isles, under the impulse of an anomaly tropopause relatively low virulent. It will drive a flow in southwestern lower layers, continuously supplied with air soft damp with values ​​of neighboring T'w 16 to 20 ° C at 850hPa.Strong momentum and will be up to the middle and upper floors, causing a ripple of the jet stream and therefore a divergent configuration on the target area, which will be positioned in left output stream.This dynamic will be grafted on a very unstable air mass. Indeed, the vertical profiles of MUCAPE present values ​​generally close to 1500 to 2000 J / kg. On an axis Pyrenees - Nord-Pas de Calais, the values ​​of MUCAPE can exceed 3000 J / kg for MULI <-10 ° K. This environment should allow the development of many strong thunderstorms over the area covered, with production of mono / multi grêligènes and possibly rainy strongly. Furthermore, primers supercells will likely also in the presence of deep shear marked. The potential storm will continue throughout the night in some areas.

Nb: Zoning risk of severe thunderstorms will continue to be refined in future newsletters, given uncertainties about the phasing / dynamic instability.

Edited June 25, 2012 by Robbie Garrett

[multi cellular thunderstorm]

I have to say, after planning long drives this week, i am thinking i would be better to stay close to home. A short drive NE may be all that is required if current outputs are correct

You look to be in a pretty good place at the moment.

I will be quite limited on Thursday, got to see the olympic torch with my girlfriend from about 6pm onwards, and roads around here are closed from 4pm, so if I do go out anywhere I will have problems getting back.

Might have a little Lincolnshire chase on Wednesday but not sure if it's worth it yet.

[Aaron]

very high dew points widespread on Thursday.. perfect

[Costa Del Fal]

Massive CAPE downgrades (as expected) on the 18z now. Looks nothing unusual now really.

[mattyk1985]

Looks like a major downgrade this latest run. Bth for Wednesday and Thursday, was to be expected though, still plenty of swings and roundabouts to go.

[Robbie Garrett]

Massive CAPE downgrades (as expected) on the 18z now. Looks nothing unusual now really.

Each run varies, this has been discussed to death over in the model forums. They all have different data inputs, as I said the likely hood is showers. It's a start.

[Costa Del Fal]

Each run varies, this has been discussed to death over in the model forums. They all have different data inputs, as I said the likely hood is showers. It's a start.

Yes each run varies but come on, you cant deny this isnt expected.

[Lewis]

A downgrade on CAPE values on the 18z

i think tonight's 18z is probably as bad it will get, it's at it's eastern most extreme, still us guys in the East and NE along with EA/SE should get some very nice storms, 900-1000 cape and LI of -4 can produce spectacular storms.

The CIN showing the likely areas for convection

Still plenty of time for upgrades.

Lewis

[mattyk1985]

You chasing on Wednesday n Thursday Lewis?

[Lewis]

You chasing on Wednesday n Thursday Lewis?

Hi Matty,

yep i'll be out both days, I'm kind of worried about the timing of the cold front engaging with the plume for thursday, I have a funny feeling that the cold front might want to push through a little earlier.

Feel free to add me to facebook: https://www.facebook.com/eastyorksforecaster

Anyone may add me

Lewis

[Robbie Garrett]

Yes each run varies but come on, you cant deny this isnt expected.

Yeah I know mate. But to be fair, I was watching everyone hyping it up... yeah I added to it, posting graphs. But to be fair, a forecast is exactly that and is never set in stone, last year was so dissapointing... 3000 k/jl - 33*C and some mad dewpoints and -8 LI across the UK, and a stalled cold front.

[mattyk1985]

How early? Guessing that would be a disaster/

[Norfolk Sheep]

I think I might practise dropping some saucepans on the kitchen floor

The problem with an overnight MCS is that over this side we end up with cloudy conditions until late in the afternoon - never fails!

And the only thing I remember about El Gordo was having to watch everyone else's videos whilst gnashing my teeth

[Lewis]

This is my biggest worry, and is one of the major factor/player which will decide whether Eastern and NE areas will get thunderstorms, or just a damp squib.

The cold front is expected to move through around 11am-12pm across NW England, N england running in to Yorkshire.

The warm moist air, and high CAPE values start building around mid-day around the East Midlands/SE England. Energy and CAPE values rapidly head North.

There's very little in the way of CIN, and dew points are generally lower than the other models on the GFS, against the NAE for example.

So this suggests to me, that the cold front may move though quickly, leaving us with overcast conditions, and a damp squib basically, if it moves through too quickly we lose our trigger.

GFS = Knife edge.

So it all goes down to this CF on Thursday for Northern areas.

If it goe's smoothly it'll be a cracker, but it can easily go wrong!

The ideal situation is for it to stall and slowly move ENE'wards, but this would be asking too much.

Lewis

Edited June 25, 2012 by Humber

[Liam J]

Well that's me off work for a week.... now wheres these storms at

Still looking good for Thursday, I just hope the front doesn't steam roll through to quickly!! Best charts we've had this season so far..... What could possibly go wrong

Need the front to stay away until we get decent some decent heating and cape kicking off or it's goodbye.....

Edit : 18z was a slight downgrade? Still not terrible though and time is one our side ATM, have faith.

Edited June 25, 2012 by Liam J

[I Cumbria Marra I]

Liam, whats our chances?

[Liam J]

The hi res Hirlam is showing dew points climbing to 15c+ overnight into Thursday from the south, no cape/lift index charts from this model? I can't find any. NAE will be coming into range overnight.

Liam, whats our chances?

I'd say moderate ATM, the timing of the front will either make it or break it. I'd like my heavy rain to be accompanied by flashes and bangs....

Edited June 25, 2012 by Liam J