Uk Convective General Discussion & Forecasts, 26th June 2012>

[Deluxe]

Harry are your eyes spinning round and round?

Too many sources!

[Paul]

I've just checked the emerging GFS 06z (which I think many people will be encouraged by TBH) has a 70% storm risk for London throughout tomorrow morning............QUE??????????

Paul, is that link you provided working ok? Which charts does the 'storm risk' tool link to?

They're using the same data but the maps are using a broader brush so to speak whereas the forecasts are pinpointing that exact location and applying a set of rules to it in order to show the storm risk.

[dave reid]

Good morning all.

Im heading out this eve with the hope of seeing some action out across the channel.

My grirl friend wants to be heading home by midnight as she is working early Thurs. Are we thinking it could kick off b4 then with some french imports or am I going to be gutted when i get home and check the radar to see it light up at 1am.

Will be heading somewhere between Kimmerage bay and portland, any thoughts on how far west from Bournemouth I should go. I promise not to blame anyone If Im in the wrong place

Just a little excited now :o

[Steve C]

This must be why the potential is so:

a) interesting

b ) infuriating

c) hard to understand

d) easy to understand when drinking beer

(delete the options as appropriate........)

Cheers Coast.

I'll now go to my local tonight and watch Spain v Portugal and have a few pints. I'll then work everything out for tomorrow, with total confidence.

[Keraunic]

I always like a good storm, but if good ol' Norwich gets one and Southport doesn't I will be even more flabbergasted!

It'll gast my flabber as well. in a nice way. Fingers crossed an all that. Hey, UEA my ol uni.

[Supacell]

I've just checked the emerging GFS 06z (which I think many people will be encouraged by TBH) has a 70% storm risk for London throughout tomorrow morning............QUE??????????

Indeed, the 06z is an upgrade for many with more of the country being affected. As for today, i think Norfolk, Cambs and Lincs still the place to be, and East Yorkshire later this evening. I will be heading out shortly towards these areas.

[AWD]

After seeing the latest tweets from my local forecaster Ian Fergusson, for the West Country, it doesn't look too promising now. UKMO high res models downplaying any thundery activity for my region!

Sorry, on phone do can't provide link!

[Harry]

They're using the same data but the maps are using a broader brush so to speak whereas the forecasts are pinpointing that exact location and applying a set of rules to it in order to show the storm risk.

Coolios, cheers Paul.

They must use wholly different formula, as on the chart London is slap bang in the middle of a 70% risk bubble....precip breaks out in the London region also on the overlay...wierd!

After seeing the latest tweets from my local forecaster Ian Fergusson, for the West Country, it doesn't look too promising now. UKMO high res models downplaying any thundery activity for my region!

Sorry, on phone do can't provide link!

Is he using the MetO models though?

GFS taking a very different line the MetO models.

Having said that, on this day last year when he poo-poo'd the risk he was spot on (as I'm sure you'll remember it all kicked off on the 28th in the end)

Edited June 27, 2012 by Harry

[AWD]

Is he using the MetO models though?

GFS taking a very different line the MetO models.

NAE and UKMO high res models ( UKMO GM 4 ) or something!

[Paul]

Coolios, cheers Paul.

They must use wholly different formula, as on the chart London is slap bang in the middle of a 70% risk bubble....precip breaks out in the London region also on the overlay...wierd!

Don't forget the forecast won't update to the 6z data until the run is complete

[Costa Del Fal]

Pretty uninspiring tweets from Ian Fergusson. Part of me says with all this instability transferring across to the UK tonight, id be amazed if nothing kicks off but then another part of me just thinks of the utter failure of these set ups in the last few years with just heavy rain and lightning limited to the English Channel. Been many years since true overnight lightning and from a long lasting storm and with our current weather patterns, I cant help but feel the same will happen again.

[Carl46Wrexham]

Upgrades...downgrades...sidewaysgrades...westward shifts...eastward shifts...

To hell with this...I for one am giving this part of the forum a swerve for the next 24 hours...no radar watching...no forecast watching. I'm going to go the old fashioned way about this event/non-event. If anything happens for me it will come without prior knowledge...and will be more enjoyable as a result.

If nothing happens..the NSC page will get a battering of posts.

Edited June 27, 2012 by Carl43Wrexham

[Deluxe]

Upgrades...downgrades...sidewaysgrades...westward shifts...eastward shifts...

To hell with this...I for one am giving this part of the forum a swerve for the next 24 hours...no radar watching...no forecast watching. I'm going to go the old fashioned way about this event/non-event. If anything happens for me it will come without prior knowledge...and will be more enjoyable as a result.

If nothing happens..the NSC page will get a battering of posts.

Good luck with that

[Eskimo]

Good luck with that

I'll give it about half an hour.

[Bobby]

The NMM is still tasty for those in the SW

NAE also looks good

40mm/hr rain rates, I can't imagine no thunder from that sort of intensity.

Edited June 27, 2012 by Barb-

[Evening thunder]

Hmm I don't like this talk of uninspiring tweets from Ian Fergusson, although if those aren't thunderstorms on the graphics on the BBC web site I don't know what they are.

Edited June 27, 2012 by Stormmad26

[Coast]

To hell with this...I for one am giving this part of the forum a swerve for the next 24 hours...

Light weight!!!!! This is the really fun bit, it's like a treasure hunt with five different maps and thousands of different people who all think they know where it's buried!!!!

#comeonyoustorms

[Nick F]

My storm forecast for today and overnight until 0600hrs Thursday:

Valid: 27/06/2012 11:00 - 28/06/2012 06:00

Headline: ... THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FORECAST...

Synopsis

Upper trough over the North Atlantic approaches western Europe during the forecast period. A broad warm sector continues to lift north across the UK during Weds behind warm front. While cold front approaches to the SW of the UK towards end of forecast period ahead of parent low moving into to the SW of Ireland. Minor shortwave troughs move NE in the warm sector, one indicated across central UK and another approaching SW UK tonight.

... ENGLAND, WALES and S IRELAND...

Warm/humid airmass in place today, with dew points reaching 16-18C on latest obs across central and E England, will become increasingly unstable with surface heating ... GFS indicated several 100 j/kg CAPE this afternoon across the eastern half of England. Mid to upper profiles will be relatively warm/moist with not particularly steep lapse rates as a result, but weak upper forcing and surface heating (cloud clearance permitting) may lead to isolated to scattered heavy showers and thunderstorms across parts of central and eastern England this afternoon. 20-30 knts of deep layer shear may allow some organisation of cells, with a risk of gusty winds and torrential downpours.

Later today and overnight, an elevated mixed layer (EML)/ high theta-e plume will advect N into SWern/S UK and S Ireland. This airmass characterised by steeper lapse rates will destabilise ahead of approaching short wave trough - bringing a risk of thunderstorms north overnight and into Thurs morning across parts of England, Wales and perhaps S Ireland. Increasing deep layer shear towards the SW will perhaps organise cells into an MCS that will track NE across SW and central S England, Midlands and E Wales towards the end of the forecast period/ 0600hrs Thurs. With perhaps more isolated storms breaking out further east. As storms will be generally elevated in nature, increasingly strong low-level shear will unlikely be utilised, though there is a severe threat possible in the form excessive rainfall from storms, so have issued a SLIGHT risk. Storms may also be capable of strong wind gusts and hail. Storms will edge further north and east during Thurs morning as shortwave and cold front following continue to move N and E, this will be covered by a later forecast.

Issued by: Nick F - Forecaster for Netweather

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[BrickFielder]

Yes its all a bit tricky to forecast. First Off lets look at todays posibilities.

Today

Models show that there is some instability available.

NMM Vorticity modelling shows a band of approaching vorticity approaching parts of the midlands and a weaker band approaching the north.

Looking at Satellite charts and comparing to other models then I think all models are likely to sligghtly wrong about placing and timing today.

There are a number of problems though with expectations that today will produce storms. First up is cloud cover and next is the rather weak mid level lapse rates.

Looking at the forecast SkewT's for today then cloud tops look limited and their seems to be moisture most of the way up through the atmosphere.

Providing the models are not too far off then storms are likely to be rare and I would not expect much more than a heavy shower. Favoured areas would be aeras with sunshine possibly towards humberside and lincolnshire.

Tomorrow

Its still too early to say much about tomorrow especially as this is a fairly dynamic situation. Met Office fax charts still suggest a trough in the warm sector ahead of the cold front. Whether that trough will occur is hard to tell with models disagreeing. Theres also suggestion of embedded storms in the cold front.

Mid level lapse rates look better tomorrow, although not exceptionally steep.

Forecast SkewT's suggest with the right forcing we could get storms tomorrow. Notice how cloud tops are forecast to be higher today and the wind field curves.

Before the storm enthusiasts get to excited there might be some caveats on the potential. First up dewpoints above 16 C are pretty rare in the UK and some models regulalry forecast dewpoints too high. So instability might be a lot less than predicted. Second up this airmass is coming up from the south and arguably Spain. Typically you get and elevated mixed layer which is not showing up well of the forecast modelling in my view. That means storms may not be surface based. Third up cloud cover may play a role or conditions may be ripe but without a triggering mechanism. Fourth the timing may not coincide with maximum daytime heating.

In other words the forecast may be subtly wrong enough so that we get no storms tomorrow and there are already some worrying aspects to the model output that mean confidence is low in the outcome.

[Kain]

My storm forecast for today and overnight until 0600hrs Thursday:

Issued by: Nick F - Forecaster for Netweather

Nick your a star Given me a little hope after seeing that 0% crap

Just been down the shop and man its muggy out there, I'm sweating like a nun in a brothel!

[Chris K]

So much variation in models I'm finding it to be a confusing and frustrating setup, yet still very interesting to follow..

Met Office still keen on minimal ppn coming into the SW tonight and a big bulk heading across Ireland and NW england into Scotland.

Tweets from our local BBC forecaster also now saying it is less likely we will get anything of note.

Estofex giving us a level 1 with the possibilites.

GFS CAPE not great for us here but not bad either - we are still in range during the morning.

Other models that people have been posting like NMM and NAE also hint at a better chance for the SW tonight into tomorrow morning...

I don't really know what to expect! I don't think I'll bother staying up though tonight. It just seems too knife edge for this area at the moment. Outside it also feels quite cool with all this drizzly muck.

I look forward to hearing stories and seeing videos of anything that does develop anywhere else in the country, but personally, at this moment, i'm not hopeful for where I live - we've been here many times before and ended up in disappointment.

Still something could happen and if not....2 months of summer to go!

(sorry my post was a bit biased into looking at the SW propects rather than the country as a whole)

[Coast]

So much variation in models I'm finding it to be a confusing and frustrating setup, yet still very interesting to follow..

I've been reading some of the forecasts and thoughts from knowledgeable people here and in other places and I have to say, not any of them are in 100% agreement at this stage. This one could be a hit, a miss or something in between in any place and that's about as accurate as I can say currently!!!!

[Liam J]

Eagerly awaits Nick F's later forecast......

Getting a little bit excited here.... *dances*

[Robbie Garrett]

Just having a look through the aviation models,

A secondary low feature develops out over the Bay of Biscay, I remember mentioning this the other day, with that kink in the pressure possible developing some Thunderstorms to head NNE/NE across the English Channel into the UK.

GFS keen on that secondary low feature to set up in the bay of Biscay.

Last time I saw a secondary low feature like that setup, it almost wiped out Belgium. Of course this secondary low is in a far better position than you think.

http://www.youtube.com/watch?v=1vlMW1dUivE

With a good amount of cape around about that time in that area of the world.

There's enough CAPE/LI overnight to start things off for something big early morning for the south coast and possible the south east of England.

Looking at the terminal area forecasts from the MetOffice, they are thinking something along the lines of PROB30 for winds to be south westerly at 23015G30KT (This is quite a bit) with 2000 meters in Heavy Thunderstorm Rain in the early morning, so rather than going to bed at stupid hours, go to bed early and get up at 5/6am depending on this evenings forecasts.

It's definately indicating something for the South East Tonight, and the precipitation models thus agree. 09z-12z (10am-1300 local)

LONDON/GATWICK EGKK 270704Z 2707/2812 24010KT 3500 BR BKN003 BECMG 2707/2709 9999 NSW BKN008 BECMG 2709/2712 SCT020 BECMG 2718/2721 VRB05KT 7000 PROB40 TEMPO 2720/2802 4000 BR -RADZ BKN005 BECMG 2802/2805 13010KT 9999 TEMPO 2808/2812 8000 SHRA BECMG 2809/2812 21010KT PROB30 TEMPO 2809/2812 18015G25KT 4000 +SHRA TSRA BKN014CB

LONDON/HEATHROW EGLL 270504Z 2706/2812 23007KT 9999 FEW012 SCT025 TEMPO 2706/2710 BKN010 PROB40 2706/2708 4000 -DZ BKN004 TEMPO 2721/2806 5000 BR -RADZ BKN006 BECMG 2723/2802 14010KT TEMPO 2806/2812 7000 SHRA BECMG 2808/2811 22012KT PROB30 TEMPO 2808/2812 23015G30KT 2000 +TSRA

LONDON/STANSTED EGSS 270459Z 2706/2812 25010KT 6000 BKN005 BECMG 2706/2709 9999 BKN014 BECMG 2709/2712 SCT020 PROB40 TEMPO 2709/2718 8000 SHRA BECMG 2715/2718 VRB05KT BECMG 2718/2721 6000 TEMPO 2720/2803 4000 RA BR BECMG 2803/2806 14012KT 9999 TEMPO 2809/2812 7000 SHRA PROB30 TEMPO 2809/2812 18015G25KT 4000 +TSRA

Edited June 27, 2012 by Robbie Garrett

[Stuart]

a bit better for me on thu now so crossing my fingers