28th Aug 2011 - Storm/convective Forecast Discussion And Reports

[Coast]

Well another grim and grey start to a day, but I have been observing some convection going on in the Channel

ESTOFEX currently have no forecast for Europe (?) but UKASF have a slight risk as follows:

Forecaster: Dan

Last Updated: 22:11 Saturday, 27th August 2011

Valid: 00:00 Sunday, 28th August 2011 - 23:59 Sunday, 28th August 2011

Areas Affected:SLGT: Midlands, East Anglia, London and Kent

Synopsis:Large upper trough/low continues to sit over the northern North Sea on Sunday with upper trough axis over the British Isles, slowly rotating eastwards. Greatest convection potential exits under the base of said trough, decreasing as the base passes through highlighted areas.

Discussion:Cold mid levels will steepen lapse rates as a result of diurnal heating. A couple hundred J/kg CAPE are likely to result in quite a few scattered showers, though less widespread and heavy compared to Saturday. Given Saturday's greater coverage and intensity of showers than initially anticipated, and a similar airmass still present, a marginal SLGT threat level has been issued to highlight regions with a slim chance at any noteworthy convective potential.

It must be noted that lightning is likely to be quite isolated, if any at all. Greatest instability exists in the afternoon across East Anglia primarily. ELT's are not particularly favourable (at best -5C) but locally some colder values are possible in any deeper pockets of convection. Marginal DLS and LLS precludes severe weather. Showers will rapidly decrease in coverage after sunset.

SkyWarn have an update in place:

SKYWARN UK SEVERE WEATHER WARNING #050

ISSUED: 2215UTC THURSDAY 25TH AUGUST 2011 (GJ)

UPDATED: 1130UTC SATURDAY 27TH AUGUST 2011 (GB/GJ)

SKYWARN UK HAS ISSUED A SEVERE WEATHER WARNING FOR THE FOLLOWING REGIONS:

EASTERN ENGLAND

NORTHERN ENGLAND

EASTERN SCOTLAND

NORTHERN SCOTLAND

ORKNEY AND SHETLAND

IN EFFECT UNTIL 2100UTC SUNDAY 28TH AUGUST

DEEPENING LOW WITHIN A TROPICAL AIRMASS GENERATING HEAVY RAIN WITH THUNDER

SEVERE WEATHER IS EXPECTED IMMINENTLY, OR OCCURRING, SOMEWHERE WITHIN THE REGIONS INDICATED. THREATS WITHIN THIS WARNING INCLUDE, BUT ARE NOT LIMITED TO:

HEAVY RAIN...PERSISTENT RAIN...FLOODING...LIGHTNING...GALES...STRONG GUSTS...FUNNELS/WEAK TORNADOES

DISCUSSION:

MODEL CONFIDENCE HAS BECOME BETTER ALIGNED WITH THE UKMO NAE, CREATING STRONG CONFIDENCE IN A SEVERE WEATHER RISK THROUGH THE WEEKEND. A LOW FORMS TO THE SOUTHWEST TRAVERSING FRANCE INTO THE SOUTHEAST OF ENGLAND OVERNIGHT. STRONG CONVECTION WILL OCCUR AND WRAP AROUND THE LOW CENTRE INTO SOUTHERN AND CENTRAL UP TO NORTHERN ENGLAND DURING FRIDAY. THE LOW MOVES DUE NORTH UP THE EAST COAST THROUGH SATURDAY INTO SUNDAY BEFORE STALLING OVER NORTHEASTERN SCOTLAND. PRECIPITATION ACCUMULATIONS ARE WIDELY 20-30MM ACROSS THESE AREAS WITHIN RESPECTIVE 24HR TIMEFRAMES, HOWEVER ACCUMULATIONS OF 40-60MM AS A RESULT OF CONVECTIVE ELEMENTS AND ESPECIALLY THE SLOW SPEED OF THE SYSTEM NEAR THE EASTERN AND NORTHEASTERN COASTS ARE SUFFICIENT TO TRIGGER A WARNING. PLEASE MONITOR WEATHER AND TRAVEL INFO AS NECESSARY. THIS WARNING MAY BE UPDATED.

Nothing close according to 21st OWS:

No CAPE or negative LI:

Some appears to get going later in the afternoon:

Strong area showing on the Scottish Borders for KO:

Lower level lapse rates up again:

Higher levels nothing special:

But here is the chart of the day, look at that tornado risk in NE Scotland!!!

[Lauren]

I'll eat my hat if we get a storm today.

[Chris K]

Wow currently having an absolute downpour of rain. One minute it was sunny, the next its dark outside and soaking.

[IanR]

not expecting anything here today, saw about 6 flashes of lightning over the merseyside area within a large cell around midnight ,close enough to hear the distant rumbles , it was fairly infrequent so I went to bed !

[Nick F]

Heavy shower just cleared here in west London, though lightning IMO will be rather isolated today if occuring at all.

Looks like a bit of a break coming up as high pressure moving this coming week, with nothing interesting storm-wise on the horizon for now.

[Chris K]

We just had a torrential shower and as it is moving away to the East, we have had 3 power surges just now as well. Possibly lightning some place nearby as this happened the other night when there was lightning to the east of Bristol, but I haven't seen any here during the shower. Very unusual this is first year I've seen our whole town gets power surges every strike during storms, usually it just flickers. Can't see anything confirmed on sferics though so am not sure.

EDIT: Looking to my south-west, dark storm cloud over the River Severn Estuary direction near the Severn Crossings. May be hitting Bristol soon and it looks like its developing slowly.

Edited August 28, 2011 by Bugganuts

[Bluebreezer54]

Some lively convection bubbling up here on the South Coast in the last hour or so. Brief but heavy downpours heading west to east, Lauren might need to get the salt and pepper ready !

[Chris K]

Another torrential shower. Not expecting anything thundery the energy just isnt there. But getting several short bursts of intense rain!

[Raidan]

Distant thunder heard NOT by me but was told by 3 people,they said it was heard just after 4pm coming from north Bristol direction.

[Chris K]

Distant thunder heard NOT by me but was told by 3 people,they said it was heard just after 4pm coming from north Bristol direction.

Yea I heard it to the East of me. Showers seem to be dying now. Not much storm potential forecast for a while now I think. Not for this week anyway.

[weatherobsuk]

Scotland seeing their own Force 10 winds today, out into the North Sea with this associated LP. causing problems for shipping.

http://www.bbc.co.uk/news/uk-scotland-highlands-islands-14699853

[Aaron]

You know, I can't help but feel jealous, I want some "real" weather..