Uk Convective General Discussion & Forecasts, 16th August 2012>

[lilclairey2012]

the pink sky has brought some heavy-ish rain. hopefully thunder will follow.

[Shaun L]

We got hit by heavy rain, well exceptionally heavy rain.. But it wasnt a thunderstorm. Still waiting to hear thunder this year!

Unreal Stephen. This side of the Wirral we had the thunder.

[Allseasons-Si]

Beautiful half rainbow here earlier from the shredded remains of the South Wales rainfall that dated to come this way. Amazing that 3 mm of rain brings a warning. Perhaps it was for the rainbow??

like this one took about 30 minutes ago

[Allseasons-Si]

That shower has died from stoke,BUT,check out them in south whales developing,come on

[Darren Bown]

The sky is completely black to my SW. Something must be brewing.

[shadowfax]

Sky was a strange pink and has now gone very black to the southwest of me and the wind is picking up.

[Allseasons-Si]

The sky is completely black to my SW. Something must be brewing.

Yeah darren,it's prob the little shower just in front of that main stuff.

[Darren Bown]

Sky was a strange pink and has now gone very black to the southwest of me and the wind is picking up.

Can see the same thing. Radar isn't showing anything exciting but I am thinking it could be something that has happened the last 15 mins or so?

[Stuart]

sorry not posted much today

Synopsis:

Sharpening upper trough will be present to the west of Britain as a thermal ridge builds to the east. In-between the two, a strong jet will be aloft with a waving surface cold front beneath, associated with a plume of very high ThetaE. Several foci for convection exist, with the most widespread sferic coverage expected over the N and NW of Scotland.

Discussion:

... N SCOTLAND ...

To the north of the waving cold front, with a rather slack surface flow, local convergence zones will form and a few showers and thunderstorms will develop. 600-800J/kg CAPE will provide the most frequent lightning over the NW Highlands, and possibly along the Moray coast where the best low-level convergence and DLS is present.

Dry air aloft will allow hail to fall in any stronger cores, potentially >1.5cm in diameter. PWAT in the upper 20s mm combined with slow storm motion may result in local flash flooding, but only after considerable moistening of the mid and lower layers has taken place since forecasting soundings are very dry.

Showers/storms are expected to decrease in coverage and migrate eastwards during the afternoon hours.

... IRELAND, N IRELAND ...

A few hundred J/kg CAPE will develop in response to diurnal heating, allowing a few showers to form. Rather poor CAPE will result in weakly-electrified storms.

... ENGLAND, WALES ...

Along a waving frontal boundary, which is classified by a plume of high ThetaE, some occasional pulses of elevated convection may form, moving northeastwards along the front, which itself will migrate slowly eastwards during the day.

While up to 1000J/kg MLCAPE would allow elevated storms to become quite electrically active, the rather isolated and 'sporadic' nature of storm distribution due to local plume destabilisation means we are unable to highlight any specific areas for MDT coverage level.

Also, PWAT is forecast to be up to 42mm, but rather dry mid and lower levels will require sufficient moistening for excessive rainfall to become a problem at the surface.

http://www.ukasf.co.uk/storm-forecasts/209

[Allseasons-Si]

Can see the same thing. Radar isn't showing anything exciting but I am thinking it could be something that has happened the last 15 mins or so?

what's that darren,a supa cell,come on let us in,i haven't got my crystal ball today lol

no,seriously i am waiting in despair now with all these pulses,somethings got to blow

[The PIT]

like this one took about 30 minutes ago

Yup highlight off the evening certainly going to be a quiet night this side of the Pennines. Amazing how those hills to south and south west kill everything off for us.

[Allseasons-Si]

Yup highlight off the evening certainly going to be a quiet night this side of the Pennines. Amazing how those hills to south and south west kill everything off for us.

Yes your'e right PIT,we need a shift from SW to S or SE for us up here to get something,it seems the showers die of death as they come up the western slopes,THEN reform to the E or NE of us,we are shelted in this S.yorkshire pit lol

[Sunny Android]

Unless the southern part intensifies it's going to miss Warrington and everything SE of Bury.

Looks like West Lancashire will get the worst !

[Darren Bown]

Unless the southern part intensifies it's going to miss Warrington and everything SE of Bury.

Looks like West Lancashire will get the worst !

There are lines of rain forming South of the band. Still nothing exciting though lol.

[carl1980]

Very heavy rain here

[Allseasons-Si]

Skies have gone dark to my SW with another shower from stoke area,lets see if this fizzles out.

[Cheshire Freeze]

Unless the southern part intensifies it's going to miss Warrington and everything SE of Bury.

Looks like West Lancashire will get the worst !

Yep too far north for most of Manchester etc from that main band. Think once that has pushed through, that's mostly it for the night?

[Darren Bown]

21:15 - intensifying of the band eastwards

Heavy rain here now.

Edited August 17, 2012 by Darren Bown

[Allseasons-Si]

Ok,a broader picture,there is some nice radar returns SW of cornwall,no sferics as of yet but keep a peeping eye.

anyone in for a long night?

Edited August 17, 2012 by allseasons-si

[Snowynorth]

flash of lightning around southport way again

[Darren Bown]

I

flash of lightning around southport way again

I saw that too, I thought I was imagining it!

[A.J]

Yep too far north for most of Manchester etc from that main band. Think once that has pushed through, that's mostly it for the night?

In a word, no......moisture rich high theta-e air will continue to pump overnight from the SW approaches so that pulses of heavy thundery rain will continue to develop and train NEwards along the front....Always the chance of some elevated convection giving a high based light display for the lucky few

Nick's lurking around the thread, so head's up for an incoming in-depth forecast (hopefully!)

Edited August 17, 2012 by ajpoolshark

[Nick F]

http://www.ukasf.co....m-forecasts/209

I agree with the forecast for storms across N Scotland, but the frontal boundary further south across England and Wales is shown by all models to weaken considerably during the Saturday, as it drifts towards eastern England, so risk of storms will diminish from early morning.

The frontal boundary develops a wave Saturday evening/night and drifts north again as warm front to lie from Cornwall to the North York Moors on latest fax for 12z Sunday. Most models show the front reactivating from the SW on Sunday, with pulses of heavy rain and storms moving NE along the boundary across SW England, Wales and N England during the afternoon. Further east, Hirlam and to a lesser extent GFS and ECM show an area of precip pushing NE from the channel across SE England Sunday afternoon, which I can only assume would be elevated thunderstorms - perhaps the NW edge of the high theta-w plume destabilising.

[paul m]

Its normally me having a huge moan and groan but mother nature can be a cow. All the ingredients are there but her magimix has broken down. Still plenty of time yet so im just relaxing radar watching. Bit annoyed as the better half has pinched me beer though!!!!!!

[IanR]

saw one flash about 15 minutes ago, nothing since, just as the cartoons say at the end,,thats all folks.