Convective / Storm Risk Discussion - 14th June 2013 onwards

[ZONE 51]

I might not be able to update the new model data this morning. 

Things to watch - 

MCS thunderstorm now moving up from France possibly into parts of Sussex and Kent today.

Convective activity across the south heavy showers today.

Mid level cas/floccus signs indicating instability.

Heavy showers turning thundery/storms most likely east of south UK later today.

Imported thunderstorms south UK late eve/overnight. risk further north too although I am staying with south/se risk at this stage as things can change. nothing is certain for the south nothing is certain for the north but it could be that even north zones could end up with thunderstorms this week.

[Nick F]

Quite an active warm front across Nern France atm, bringing some thundery rain, this clipping east Kent. More thundery rain to the south looks like moving in across southern counties through Monday, as the warm front lifts north. Some thundery looking skies here in south Kent atm.

Edited June 17, 2013 by Nick F

[Lynxus]

Nice storms south of the UK.. Woah.

 

[Coast]

Nice storms south of the UK.. Woah.

 

 

Are they heading this way in the next 24 hours? Maybe......

MCS thunderstorm now moving up from France possibly into parts of Sussex and Kent today.

 

 

 

 

[Coast]

ESTOFEX have it all very close to our shores:

 

 

Storm Forecast

Valid: Mon 17 Jun 2013 06:00 to Tue 18 Jun 2013 06:00 UTC

Issued: Sun 16 Jun 2013 21:31

Forecaster: GROENEMEIJER

 

A level 1 was issued for W France, central France, NW France, the BeNeLux countries mainly for large hail, and to a lesser extent for tornadoes and severe wind gusts.

 

SYNOPSIS

 

Monday morning a mid-level low will be cutting off from the westerlies reaching the NW of the Iberian Peninsula on Tuesday morning. The system is sourrounded by a strong cyclonically curved mid-level jet with wind speeds in excess of 35 m/s at 500 hPa on its southern and eastern flanks. Along an axis from the southern UK toward the Alps, a ridge builds at mid levels with significant height rises. A plume of warm air is advected northward across much of western and central parts of Europe. Despite relatively strong lapse rates over western Europe and abundant humidity in some areas, a strong cap will likely prevent convective initiation in most places. Storms may however develop along the edges of the warm air and in the vicinity of mountain ranges. The extent to which this occurs is the greatest factor of uncertainty for this forecast.

 

NW, W and central France, BeNeLux...

 

Numerical models suggest that clustered convective activity will be ongoing over western France early on Monday. These storms appear to be associated with a maximum of warm air advection that is forecast to translate northeastward into the BeNeLux countries during the evening. The system, as simulated in the models is elevated and occurs on the cold side of an northward advancing surface warm front. This should mitigate the overall severe threat. Nevertheless, it is thinkable that some surface-based storms will develop as well, and benefit from strong deep layer shear (0-6 km bulk shear 25-30 m/s) and a strongly helical flow (300 m2/s2 storm-rel helicity). The environment would then be supportive of supercells with a risk of very large hail, severe winds and perhaps a tornado. Presently, this scenario is not supported by NWP models. With the elevated storms, severe hail should be the biggest threat. If confidence in the development of surface-based convection and/or in a high convective coverage increases, an update to a higher risk level may be warranted.

 

[Adi F]

Cape is not great for this evening but LI looks good.

[Coast]

GFS based Lightning Wizard charts have it remaining in France at midday:

 

 

Wish we'd gone on a chase through the Channel Tunnel now eh?

 

 

Will the mass of sea halt progress from imports?

 

 

 

 

Let me look at a later time-scale, as this could drag on through tonight into the early hours

[Lynxus]

ESTOFEX have it all very close to our shores:

 

 

Tbh, I trust estofex a lot. Every year they are almost spot on every time. ( Sometimes can be hit and miss regarding UK potential ) but for the rest of euro, its normally very accurate.

 

If they don't have a warning for us ( L1 or higher ) then I pretty much scrub any chances of a good storm.

 

That being said, We do have a warm pool of air moving in so I wouldn't be shocked if something did kick off in the south and southeast,

I cant see any obvious convergence so I suspect it would be surface based rubbish. But who knows.

[Coast]

So what about later today or early tomorrow?

 

MLCAPE pegs right back, as you might expect:

 

 

But look at The South coast:

 

 

 

Perhaps it's going to be an all night watch!

[Lynxus]

So what about later today or early tomorrow?

 

MLCAPE pegs right back, as you might expect:

 

 

But look at The South coast:

 

 

 

Perhaps it's going to be an all night watch!

 

 

I have a feeling its going to be "One of them summers" again lol.

Cant remember the last storm to pass through here now. Ive had to go and find em myself!

[JK1]

so chance for Worthing area this time? I hope

[Coast]

so chance for Worthing area this time? I hope

 

Maybe, compare the NMM MLCAPE and TT index charts for 15z today and then 04z tomorrow, the LI/CAPE is unbelievable right over Eastbourne and the surrounding area tomorrow early doors!!!

 

 

 

 

[Summer Sun]

New update from UKASF late last night

 

Synopsis:

 

Trough disruption over the eastern North Atlantic will result with a sharpening upper trough over Iberia. The British Isles will sit beneath a slight upper ridge, on the forward side of the upper trough. At the surface a warm front will straddle the English Channel/northern France for much of the forecast period. Behind the front, an airmass characterised by high ThetaE will slowly advect northwards through Monday.

 

Discussion:

 

Firstly, it is worth noting that this forecast period runs until midnight Monday night (ie 23z Monday). It is likely that thunderstorms will develop/continue beyond this forecast period over parts of the highlighted (and possibly other) areas.

... SE, CS & SW ENGLAND ...

As high ThetaE continues to advect northwards through the latter stages of Monday afternoon, and through the evening and overnight, isentropic upglide will allow scattered elevated showers and thunderstorms to develop over the English Channel and neighbouring coastal counties in an environment of significant MLCAPE. In addition, surface-based thunderstorms over northern France will become increasingly elevated above the PBL as they continue to drift slowly northwards through the evening hours. Best period of development appears to be from 18z through to the end of the forecast period.

30-40kts DLS (corrected for elevated potential) will allow elevated thunderstorms to become reasonably well-organised and last for some time. Due to the elevated nature of the convection, severe weather will be limited somewhat, but hail is possible (perhaps a local event >2.0cm in diameter) in any stronger cores, along with the risk of local flooding given PWAT values >30mm with slow-moving storms.

Even at this stage, two main uncertainties will affect this forecast, both of which NWP tend to struggle to resolve. The first is the nature of the Iberia trough disruption, and therefore how far north the zone of elevated convection reaches - the SLGT may need to be extended further north if conditions warrant nearer the time. The second uncertainty is how much mid-level convection will be generated. Given the amount of instability forecast, it would be preferable to upgrade *some areas* to a MDT, but at present the areas most likely to see more widespread convection (and hence coverage) remains uncertain. Therefore, we may upgrade to a MDT during Monday, depending on the forecast evolution.

 

http://ukasf.co.uk/storm-forecasts/251

[Rustynailer]

Looks like rain and thunder heading North towards my location at the moment. Fading slightly as it moves North.

I hope for something later on today looking at Summer sun's comments above.

[Coast]

While we are waiting, a couple of webcams to keep an eye on:

 

http://www.rouen-live.com/

 

http://www.paris-live.com/

[Mapantz]

I may well head up to the Purbeck hills this evening, radar depending of course.It's pretty warm and humid here for this time of the morning. Temp at 17.8°C humidity at 78% dew point at 14°C that makes my humidex 21.1°C Fingers crossed for later on. 

[Coast]

I may well head up to the Purbeck hills this evening, radar depending of course.

 

Tilly Whim or Durdle Door? 

[Mapantz]

Tilly Whim or Durdle Door? 

 

Unlikely i'll go that far, it's a bit dodgy at night time and more so with all the land slips. The Purbeck hills have a higher vantage point, facing South you can see right out to sea, facing North, you can pretty much see half of Dorset, sometimes you can be above certain cloud levels too. Brillaint view point and only a 4 mile trip!

[Stormyking]

Theres a lot of AcCas about here, also a mid level show just passing to the East of us . 

What I like is the are of blue sky is and the sun coming out, and feeling very warm and muggy, hopefully it will help to feed some goodness later!

 

Edited June 17, 2013 by Coast

[nanu]

shame its all breaking up as its moved north, which is what usually happens every year.. anyway do we have any hope of any home grown stuff?? because the sun is shining and its lovely and warm out now.

[Harry]

Air feels as though its getting muggier...in comparison with first thing this morning at any rate.

 

Looking forward to the next few days...the unpredictability of it all makes it all the more interesting

[Eskimo]

Theres a lot of AcCas about here, also a mid level show just passing to the 

That's a storm chasers dream cloud!

[chionomaniac]

Anyone seen the DP's for Wed afternoon - 21C through a large portion of Southern England ( according to the GFS). Juicy - It will go bang! 

 

CAPE and LI good as well.

[Tom Jarvis]

Theres a lot of AcCas about here, also a mid level show just passing to the East of us .

What I like is the are of blue sky is and the sun coming out, and feeling very warm and muggy, hopefully it will help to feed some goodness later!

Sorry about the angle of the photo

Does that mean you are seeing lightning or something else

Ps it is still cloudy here

[Coast]

Anyone seen the DP's for Wed afternoon - 21C through a large portion of Southern England ( according to the GFS). Juicy - It will go bang! 

 

CAPE and LI good as well.

 

Best potential of the year so far in this part of the World