6 July 2011 - Storm/Convective Forecast, Discussion And Reports

[cmimrie]

London and South East (which includes Hampshire)

Where can you see this, I can't see anything on the website?

[Purplepixii]

Here

[Stuart]

Last Updated: 21:27 Wednesday, 6th July 2011

Valid: 06:00 Thursday, 7th July 2011 - 05:59 Friday, 8th July 2011

Areas Affected

Most of the British Isles

A well developed, vertically stacked area of low pressure will be centred near western Ireland with various occlusions and upper troughs wrapped within it's circulation. Areas of positive vorticity advection combined with a broad upper trough axis centred near Ireland will combine for an unstable atmosphere across most of the British Isles through Thursday and into Friday.

Discussion:

A large area of convective potential is possible. In fact almost all areas across the British Isles have the potential of seeing at least a sharp shower/heavy downpour and rumble of thunder.

Main risk of thundery activity will likely set up near an upper trough/band of PVA that looks to push out of eastern Ireland during the morning and into western parts of Britain around midday before moving into eastern Britain during the afternoon. Midday SBCAPE values will likely be in the range of 600-800j/kg across NE Ireland before increasing to similar values into afternoon across Britain.

**An area of complication will be E/SE England as a band of cloud associated with an occluded front brings showery rain during the morning (some of which could be heavy). This will likely lose it's definition into the afternoon, giving way to some sunny spells which will allow for surface based convection to form. Therefore, thunder risk in this area will likely be a little later in the afternoon.

DLS values will be weak to modest in the range of 25-30kt, this may just be enough for some tilting updrafts, but storms will likely form lines/clusters anyway due to vorticity banding around the low. LLS shear looks best during the morning across northern Britain and Ireland so convergence funnels will be possible with showers there. (It should be noted that funnels are fairly common in this synoptic setup (vertically stacked lows) in Britain during the summer time, mainly due to the multitude of convergence boundariess available to showers. Funnel / tornado risk will be greatest along these convergence boundaries during the middle of the day in the N and W, however LLS becomes more favourable during the afternoon across SE England, so heavier showers (stronger updrafts) may bring the risk of funnels later in the afternoon to East Anglia and SE England.

In summary, it's a complicated broad convective set-up with a zone of heavier/thundery showers likely developing in the west during the morning and moving eastwards into the afternoon

http://www.ukasf.co.uk/storm-forecasts/32

[Raytheon]

Heavy rain that past 40 mins ago over Corscombe, Dorset in the South West. Heaviest rain we've seen for a while.

Currently its soaking the girlfriend in Yeovil up the road.

[Dom W]

Had some heavy showers pass by Shotton in the last few hours, I thought I was going to hear thunder at some point.

[lorrie]

had heavy rain in seaham but no thunder thought we may have had

[Dom W]

had heavy rain in seaham but no thunder thought we may have had

I agree the skies looked very threatening, saw some very heavy rain heading for Seaham earlier; between 8.30 and 9.00

[Alex95]

Look at those heavy showers across Western England and Wales now - they will require very little daytime heating to turn into thunderstorms. I have said this before, but tomorrow's setup is better than a Spanish Plume for much of Northeast England, and can be better elsewhere too as those Spanish Plume storms can be spoiled slightly by low visibility.

[shuggee]

New thread for Thursday open now:

There's also the general thread for more storm information.

[Gord]

Each shower that's coming through here seems heavier than the last. I would be looking forward to tomorrow if I lived further east right now.

Quite a squally night out there right now.

[Costa Del Fal]

Each shower that's coming through here seems heavier than the last. I would be looking forward to tomorrow if I lived further east right now.

Quite a squally night out there right now.

Indeed, could be a fairly showery night but nothing too interesting all the same. A small chance of something here tomorrow Thundery wise but a better risk Friday imo.