UK Convective General Discussion & Forecasts

[rossco89]

Looks like we might be getting something here in Ayrshire. Some very heavy showers moving up the long the coast with a couple of flashes where I am. Sky is a lovely violet colour!

[ZONE 51]

Just popped back in as i now see we have a thundery period coming up for southern England, looks as though southeast could see thunderstorms, the risk starts today tuesday 25th october ,we could see thunderstorms and hail so really quite exciting, could someone take a look at this today as i have to go now, it does look interesting! maybe i might see a night storm!

[Coast]

ESTOFEX:

Storm Forecast

Valid: Tue 25 Oct 2011 06:00 to Wed 26 Oct 2011 06:00 UTC

Issued: Mon 24 Oct 2011 23:45

Forecaster: KOROSEC

... western France and south UK ...

Areas further north across the bay of Biscay and WNW France/SE UK will be affected by maritime airmass with very cold mid level temperatures. Expect widespread low-topped showers and thuderstorms in weakly sheared environment. Those could locally produce some marginal hail and excessive rain due to their slow moving nature. Activity will be spreading from SW towards NE as the upper cold core makes its progress towards northeast.

UKASF:

Last Updated: 18:16 Monday, 24th October 2011

Valid: 00:00 Tuesday, 25th October 2011 - 23:59 Tuesday, 25th October 2011

Areas Affected:

SLGT: SE, CS + SW England, S + W Wales, E Ireland, Northern Ireland, SW Scotland, Outer Hebrides

Synopsis:

Upper trough becomes increasingly negatively-tilted with two discrete centres, one south of Iceland and another moving northwards over the Irish Sea. Widespread coastal convection is expected behind the cold front.

Discussion:

Cold mid-levels (<-30C at 500mb) overspread the areas of interest behind a slow northeastward-moving cold front, steepening lapse rates. With warm SSTs and cold air aloft, up to 600 J/kg CAPE will develop, generating widespread showers over seas. Prevailing winds will allow showers to move inland, but given colder land surface temperatures they are likely to weaken the further inland they move.

Thus, lightning activity is likely to be quite a coastal feature, and locally there could be some significant rainfall accumulations from 'shower trains'. ELTs as low as -40C is supportive of lightning in places. Given cold air aloft, hail is likely in many of the showers, locally moderate in size.

DLS >50kts and LLS >50kts (speed) would suggest the majority of shear is in the lowest km of the atmosphere and this progressively declines during the day. Nevertheless, it may allow for some separation of updrafts and downdrafts to sustain cells, but a lack of directional shear precludes the risk of a tornado.

Main threats are moderate-sized hail and excessive precipitation. Showers will persist throughout the night close to coasts, increasingly so across the SE & E Anglia later.

[Coast]

Another day of messy rain, some of it convective:

Nice bit of CAPE along Southern coasts later this afternoon

NMM TT index looks good along the South through the afternoon:

[wimblettben]

Even though there is a good amount of CAPE around for the south I don't see there being any lightning due to the lack of surface heating. Any lightning activity is likely to only be reserved for the coasts and inland it will probably be just heavy showers.

So I am not really getting excited about it.

[Harry]

:yahoo:

So exciiiittteeeeeeeeedddd!!! On balance my chances I suspect are relatively slim, but the thought of maybe seeing some distant flashes is enough to get me going at the moment!!!

Reads very well on Estofex, UKASF, MetO...quite rare to see all mentioning the risk of thunder at the same time and all fairly confident as to timing and the rest of it!

Wooohooooo!!!!

Even though there is a good amount of CAPE around for the south I don't see there being any lightning due to the lack of surface heating. Any lightning activity is likely to only be reserved for the coasts and inland it will probably be just heavy showers. So I am not really getting excited about it.

Don't be daft man!!! (I'm not being offensive, just attacking pessimism after months of pants weather!!!!)

Where we lack heating, we will make up for in very cold uppers...for example, surface heating kicks off convection because the heated air rising. While we lack surface heating, upper temperatures will plummet...the effect of this is that the air near the ground 'heats up' relative to the plummeting air temperature above.

The further inland you are (i.e me) the risk falls away rapidly. The heat of the Channel, which at this time of year is around (I think) the 16-17C mark is sufficient for widespread convective and thundery weather around coastal areas and immediately inland.

In the past few years I've seen some very aggressive coastal storms at this time of year, producing quite frequent lightning and impressive echoes on radar...if I were in Dymchurch tonight I'd be very excited indeed

[wimblettben]

So exciiiittteeeeeeeeedddd!!! On balance my chances I suspect are relatively slim, but the thought of maybe seeing some distant flashes is enough to get me going at the moment!!!

Reads very well on Estofex, UKASF, MetO...quite rare to see all mentioning the risk of thunder at the same time and all fairly confident as to timing and the rest of it!

Wooohooooo!!!!

Don't be daft man!!! (I'm not being offensive, just attacking pessimism after months of pants weather!!!!)

Where we lack heating, we will make up for in very cold uppers...for example, surface heating kicks off convection because the heated air rising. While we lack surface heating, upper temperatures will plummet...the effect of this is that the air near the ground 'heats up' relative to the plummeting air temperature above.

The further inland you are (i.e me) the risk falls away rapidly. The heat of the Channel, which at this time of year is around (I think) the 16-17C mark is sufficient for widespread convective and thundery weather around coastal areas and immediately inland.

In the past few years I've seen some very aggressive coastal storms at this time of year, producing quite frequent lightning and impressive echoes on radar...if I were in Dymchurch tonight I'd be very excited indeed

I'm not getting excited because I am in south Wiltshire which is quite a long way from any coast. So therefore unless I travel over 30 miles it is unlikely that I will see any lightning.

[philglossop]

That shower that came through about 20 minutes ago had some soft hail mixed in. Plus whats that leaving France...........could that become electrical?

[Robbie Garrett]

Where have you been all my life??

[Coast]

Even though there is a good amount of CAPE around for the south I don't see there being any lightning due to the lack of surface heating.

Well, we have had some pretty good sunshine most of the morning, so that will help things along.

That shower that came through about 20 minutes ago had some soft hail mixed in. Plus whats that leaving France...........could that become electrical?

Nothing on the detectors yet, still a few hours to go maybe?

[wimblettben]

There is a whole stream of dark altocumulus blocking out the sun so my chance is even more slim now.

Hopefully it will clear away later.

[Harry]

There is a whole stream of dark altocumulus blocking out the sun so my chance is even more slim now. Hopefully it will clear away later.

Altocumulus can be a good sign!!

What type of Ac is it ben?

[wimblettben]

Altocumulus can be a good sign!!

What type of Ac is it ben?

It's hard to tell but I would say that it is Altocumulus lenticularis.

It is quite flat and isn't lumpy.

[Lauren]

A nice thunderstorm would round my birthday weekend off nicely. A present from Thor maybe?

[Harry]

A nice thunderstorm would round my birthday weekend off nicely. A present from Thor maybe?

Happy Birthday Lauren

It's hard to tell but I would say that it is Altocumulus lenticularis. It is quite flat and isn't lumpy.

Hmm...the 'lumpy' ones are better, although it does signify moisture at mid levels which isn't a bad thing.

There's a line of activity moving North from the Channel at the moment and has your name on it. The SW is favourable during more daylight hours before diverting eastwards towards evening time and overnight.

I think where things develop it could be quite rapid...I often find the later into the year you get, development can be quite quick along with electrification (i.e get flashes from fairly innocuous looking clouds)

[philglossop]

That lot from France that I mentioned above is just arriving. Gone very black in the Channel.

[Lauren]

Happy Birthday Lauren

Hmm...the 'lumpy' ones are better, although it does signify moisture at mid levels which isn't a bad thing.

There's a line of activity moving North from the Channel at the moment and has your name on it. The SW is favourable during more daylight hours before diverting eastwards towards evening time and overnight.

I think where things develop it could be quite rapid...I often find the later into the year you get, development can be quite quick along with electrification (i.e get flashes from fairly innocuous looking clouds)

It was yesterday, but we're spreading the celebration over three days. Saturday was Thorpe park, yesterday family and cake and Wednesday a posh steak dinner. So I still consider myself celebrating!

[Harry]

It was yesterday, but we're spreading the celebration over three days. Saturday was Thorpe park, yesterday family and cake and Wednesday a posh steak dinner. So I still consider myself celebrating!

Wow now that is making the most of it it's mine next week and I'm writing down tips as I type

[wimblettben]

Starting to allready lose hope now. It is just raining lightly at the moment.

[Harry]

Fair amount of convection kicked off in the past hour or so...some nice dark skies around London at the moment with some nice towers about.

Sets up an interesting evening/night IMO.

[Robbie Garrett]

Fair amount of convection kicked off in the past hour or so...some nice dark skies around London at the moment with some nice towers about.

Sets up an interesting evening/night IMO.

Would be nice to get a nighttime MCS, last time I remember one of those was during the 1999 brixton bomb in Iceland. Not sure if anyone remembers that, but on that evening it was extremely thundery, with constant lightning. Also during that period, the bomb went off.

However I think we've had a few since, but cannot for the love of life remember.

It was yesterday, but we're spreading the celebration over three days. Saturday was Thorpe park, yesterday family and cake and Wednesday a posh steak dinner. So I still consider myself celebrating!

Happy Belated Birthday Miss, hope you had a good day and interesting few days

Edited October 25, 2011 by Robbie Garrett

[wimblettben]

Nothing showing up on StrikeStar apart from one old stray strike in southeast england!

[Raytheon]

The prediction Bristol might get some seems to ring true down here in Yeovil ... (See pic)

As for me, the partner and I were just heading out the door to go chase when our grumpy landlord and her bratty 13 year old daughter jumped us. Now im having to paint her room whilst landlord chainsmokes in my face

#prayingtobehitbyCG

[wimblettben]

The prediction Bristol might get some seems to ring true down here in Yeovil ... (See pic)

As for me, the partner and I were just heading out the door to go chase when our grumpy landlord and her bratty 13 year old daughter jumped us. Now im having to paint her room whilst landlord chainsmokes in my face

#prayingtobehitbyCG

You don't need to worry because there's nothing out there to chase anyway.

It would be a waste of you're time unless you were planning on storm chasing down the Dorset coast.

[multi cellular thunderstorm]

Getting a little interesting here in Nottingham, it's pretty dark to the south and the radar is showing some showers heading this way.

A handful of strikes on the Netweather detector too.

Got a timelapse going and another camera ready for some stills just in case.

At the very least it looks like some heavy showers on the way, I wasn't expecting this until late tonight.