Convective/Storm Discussion

[Harry]

Not expecting much here today :lol: Probably the Kent and EA coasts are favourable for action, or seeing some pretty nice Cb's out at sea, otherwise going to be little, despite GFS' 40-50% storm risk.

Noticed that the Friday 00z FAX chart has a trough sitting slap bang over me at midnight tonight. Might be worth a watch.

Edited November 5, 2009 by Harry

[Tn9]

Not expecting much here today

Me neither,N France seems quite in on the good showers again,what with the warm water and all,[which is is colder in the summer and interferes with our northern tracking storms]seems like heads they win ,tails they win too ,had what i thought was a fair old shower coming yesterday,but was all spent time it reached here,nice sunset though :winky:

[TonyH]

Local flooding of a minor nature today in the north of the County where 50mm has fallen since yesterday evening in parts. Persistent showers streaming off Cardigan Bay almost constantly, with my area seeing generally fewer and lighter showers (only 10mm here), and further to the SW the showers have largely missed.

[NL]

A level 1 severe risk for southern Wales, south west stretching along the south up to a small part of the south east of England mostly for severe wind gusts but an isolated tornado is possible. Most of Ireland and outermost western parts of the UK under a thunderstorm risk from ESTOFEX for Friday.

http://www.estofex.org/

[Coast]

A level 1 severe risk for southern Wales, south west stretching along the south up to a small part of the south east of England mostly for severe wind gusts but an isolated tornado is possible.

Been showing up for a short while, that one

Not backed up by the UKASF, yet. But look at TORRO's forcast!!!

Friday November 6 2009 is another day which could be potentially interesting, although it must be stressed that the conditions don't look as favourable tomorrow as they did for Tuesday (at this stage). Frontal system moves east tomorrow, with a notable 'surge' of lower theta-w air behind the cold front in central/southern parts of the UK tomorrow afternoon. Initially, though, an upper ridge will be in place, but an advancing trough is progged to impinge upon the frontal plume through the afternoon. This looks like causing the front to become more active as it does so - slight instability is progged just along and ahead of the frontal zone across the area of interest...the surge of lower theta-w air may lead to another line squall, and 0-1km shear looks sufficient, should a line develop, for misocyclones to evolve. These would bring the risk of strong gusts and perhaps tornadoes. Behind the front, a marked surface trough is progged to appoach SW England and S Wales in the early-mid evening hours. A short line of convection may accompany this, again with a chance of strong gusts - tornadoes may be possible in favoured coastal locations, such as the Bristol Channel, where topography may assist the development of low-level vorticity. These showers and perhaps thunderstorms will spread eastwards across S England tomorrow night, although stronger convection is likely to remain close to the south coast.

What do the pretty pictures show?

Verrrryy interesting for early evening onwards!!!!

[Harry]

This sounds awesome! My excitement is unconfined! But I am far more unfamiliar with these sorts of setups (ie autumnal) than I am with Springtime and Summer...so I am basing this on the prognosis from Torro and Coast's excitement

[Coast]

so I am basing this on the prognosis from Torro and Coast's excitement

Controlled, but still:

[Coast]

No hints in the Cambourne 12Z sounding

[Harry]

Boooo!! What is noticeable though, should any convective potential begin to form later (as is predicted) the wind parameters do look fairly in favour of possible tornadoes....so bloody irritating though isn't it - we spend most of the year with some nice CAPE and more often than not, some good 'parcel' conditions, BUT, lack favourable window parameters to keep things remotely intense or severe.

On this occasion, we lack everything else BUT wind parameters.....not fair, lol

[Coast]

Yep, I guess anything coming this way will be later on, possibly even after the booze induced sleep of a Friday night!!

Mind you, a tornado would wake me up :unsure:

[Jane Louise]

TORRO'S latest warning!! could be fun tonight aslong as everybody stays safe.

http://www.torro.org.uk/site/forecast.php

[Coast]

TORRO'S latest warning!! could be fun tonight as long as everybody stays safe.

especially where coastal topography comes into play (e.g. Bristol Channel).

I hope you catch a storm before the year is out Jane Louise, but keep your head down! :lol:

[Stuart]

Good i am in the Yellow box

[Jane Louise]

I hope you catch a storm before the year is out Jane Louise, but keep your head down!

Thank you Coast, I have moved house now where the good storms are meant to be lol (only 10 minutes away from my old house lol)

Knowing my luck if anything does happen, it will be ruined by the big firework display tonight up the road. ( I expect I will think the bangs and flashes from the fireworks are a thunderstorm) lol

[A.J]

hmmm...interesting forecast for this evening/overnight...I'll be watching NW Radar with keen interest! :lol:

[Harry]

I agree, I think the worst (or best :lol:) of any conditions will occur nearer coastal areas. That is not to say however thunderstorm activity won't initiate further inland. An injection of warmer and more humid air is expected to appear across more inland areas of C and S England overnight, which would have IMO a similar effect to that which you get from the warm SSTs.

I think while coastal areas would be rather more at liberty to get excited, more inland activity cannot be ruled out, and for this reason I think Torro are right to have issued a far wider risk area.

Any events though, as mentioned, are likely to be shortlived, while bursts of intensity rather isolated - so it is fair to say many in the box will get nothing more than a shower....hopefully not, but the higher of probabilities.

Edited November 6, 2009 by Harry

[A.J]

Just so that everyone who happens to be included in TORRO's risk box doesn't get their hopes up, the main risk of general or severe storms will be confined to near coasts. The SW, south Wales and near to the south Coast is where the main risk lies. A few 100j/kg of CAPE across relatively warm SSTs with steep lapse rates should provide sufficient instability for storms, with a trough following on behind the main front tonight.

I'm certainly not expecting anything remotely convective for Birmingham, or any close surrounding areas.

Sorry mate, but I disagree with you on that last point...I would expect some lively showers to pass through the west midlands later on tonight....Time will tell :winky:

[SteveB]

Didn't realize storms were reported for tonight.

[Harry]

An almost mini squall line has just past through - some torrential rain at times and occasional gusty winds. Nothing sferical about it however.

Having said that, its the trough rattling across the SW at present which is the feature to keep an eye on. Some already nice echoes coming from it, and with it expected to intensify later, could get interesting.

[Nick F]

Didn't think much of the severe potential touted by TORRO and Estofex associated with the frontal system moving east earlier, there just didn't look like there'd be any instability despite the upper level divergence, so was hesitant about issuing a convective forecast.

However, tonight/tomorrow we see lapse rates increase from the west as upper low moves in from the west, so expect some isolated lightning near west and SW coasts especially towards Atlantic and Irish Sea coasts of the west ...NW forecast issued until 00z Sunday:

http://www.netweather.tv/index.cgi?action=convective;sess=52b45afc78ab15e46d0458b7a9d4ca4b

[MP-R]

Torrential driving rain with very strong winds here at present, not sure if there is a bit of hail mixed in either. Looked at the radar and a squall line has most certainly set up - what a nice surprise!

http://www.raintoday.co.uk/

[WeatherXP]

Radar shows some pretty intense cells near the southwest, but no lightning activity as yet.

[Nick F]

Recent sferics over Weston to Bristol area, anyone got thunder there?

[Marcus_surfer]

keeping an eye out for those showers over southern ireland, they could bring some nasty downpours later, had some hail showers here last night

[Nick F]

There is some sferics showing over SW Ireland now in that rash of heavy showers there merging together associated with a trough and occlusion moving SE. Given the rather steep lapse rates moving E with cold upper low, could be some moderate size hail in these heavy showers + the odd lightning strike and gusty winds.