Conv/Storm Discussion 31/5 & Early June

[Stuart]

Nice pics mark

[PersianPaladin]

About 200kj of available CAPE ahead of a weak occlusion to the west; some decent low-level wind convergence in the northern pennines region with some help from orographic lift locally; although mid-level steering winds may hinder the movement of any convective development significantly eastwards except for perhaps the far north-west of County Durham, Tynedale and Northumberland. Rogue showers cannot be ruled out though. Good moisture feed for any development although lapse rates suggest a bit of a warmer layer aloft which will limit convection east of the pennines.

Lets see what happens anyway.

Edited June 3, 2007 by PersianPaladin

[Nick F]

Recent satellite images show a distict line of convection along a wind convergence line from South of London up thru the spine of England to Northumberland.

Gone rather cloudy here in T/Wells with alot of convective infill - some dark grey bases just to the East - so maybe a chance of a shower around here and maybe isolated showers elsewhere along the line NW of London. Main threat of heavy showers looks to be over NE England - where moisture is more evident looking at 12z soundings and capping more likely to be breached particularly with a combination of orographic uplift and wind convergence.

Main barrier to any widespread showers over Nern England is rather weak lapse rates aloft due to a nose of relatively warmer air above 650-700mb looking at Nottingham and Albermarle (NE England) Soundings. Also, high cloud from the frontal boundary seems to spilling in from the West over Nern England, which may limit insolation.

[Darren Bown]

All high level cloud here, but looking east I can see much thicker clouds. I'm just west of the convergence that's going on at the moment.

Daz

[Hywel]

Torrential rain here but no thunder or lightning yet!

[Snowyowl9]

Very heavy shower here too as the wind turned to the NW about an hour ago temp drop to 15.9c.

It came out of the blue!!

Edited June 3, 2007 by Snowyowl9

[Nick F]

1500hrs satellite of UK shows the convergence line nicely, upper cold front/trough arriving from the West ahead of sfc front maybe sparking heavy showers out of high cloud across North Wales, convergence still producing showers over the North Pennines too:

Some dark cloud bases lurking above the house here, looks like it will drop rain any moment. Tcu which has developed along the convergence line from here upto N England looks like it will be too capped to form anything more than a few showers here and there.

[PersianPaladin]

Well I can see the shower clouds several miles out to my west, but it looks like they will pretty much stay there and convection will likely not spill-over eastwards given that warmer layer and cap that is unlikely to be breached east of the orographic convergence zone....save perhaps an isolated location.

[Stormraider]

Looks to be doing the same over the Welsh border too PP, not moving very far if at all. Looks like they are fading anyway.

Have had one or two spots of rain... nothing more.

[stormchaser1]

Its looking very grey to the SW of me , cloud cover completeley masking the Sun, Temp here has dropped from 20.1c at 1400hrs to 15.8c at 1735hrs , dew point is 11.2c Humidity has risen slightly from 64% to 72% This cloud looks as though its travelling straight up the North Pennines

nigel

[johnholmes]

re the area of cloud on the sat picc above, from about Nottingham to Reading then se.

Take a look at the two sat piccs below, Saturday then Sunday, its the same line of cloud that has slowly moved east and is being overtaken/masked by more Ci Cs.

Unusual for such a feature to last on sat piccs for so long.

Saturday

Sunday

John

[PersianPaladin]

Pretty beefy shower broken out in the Yorkshire Dales region...probably to the west of Harrogate.

Teesdale region also developing local precip rates of 42 mm/hr and greater.

Also evidence of slow encroachment of the convergence zone eastward....will it maintain development? I doubt it. Looks like we are reaching peak development in the northern pennines region. No sign of any thunder\lightning thus far.

Edited June 3, 2007 by PersianPaladin

[stormchaser1]

PP

If and a big IF any storms develop down your way over night , try and keep um there till tomorrow morning , thats when i shall be heading down your way , First deliveries Lanchester area , around 0800

Nigel

[PersianPaladin]

PP

If and a big IF any storms develop down your way over night , try and keep um there till tomorrow morning , thats when i shall be heading down your way , First deliveries Lanchester area , around 0800

Nigel

Haha, if any storms actually manage to develop over my area tonight....I WILL run outside completely naked and scream like a wild yeti.

[stormchaser1]

Now you dont want me to smash the van up do you ???

I can imagine the headlines

No i wont post that one ha ha

All going well i should be in Consett tomorrow afternoon , down by Edmunbyers/ Blanchland/ Muggleswick areas, and if there are any decent piccys to be taken i will be ready ,

nigel

[PersianPaladin]

Well the BBC think that convection and scattered thundery showers are still likely in NE England this evening and tonight....but I think it will be a case of them (currently in the pennine region) slowly fizzling out by late evening...with only isolated downpours making their way eastwards.

If you do catch any cells tho....expect some beefy downpours.

You can see the line of convection is pretty organised up the spine of Northern England: -

Edited June 3, 2007 by PersianPaladin

[multi cellular thunderstorm]

This seems to suggest that the convergence has moved further west.

http://www.meteorologica.info/UKstreamlines.htm

I'm suprised those heavy showers over the Pennine area are not thunderstorms

[PersianPaladin]

This seems to suggest that the convergence has moved further west.

http://www.meteorologica.info/UKstreamlines.htm

I'm suprised those heavy showers over the Pennine area are not thunderstorms

Those streamlines are either talking about about very high level winds or they are just plane wrong (or illustrating a much earlier time).

[Thundersquall]

The convection looks quite nasty with some big downpours in places.

The Met Office radar also shows this quite nicely, with a line of heavy downpours along the Pennine Chain

to NE of Manchester. Another line of heavy showers and downpours has recently developed to

the NW of Birmingham.

National radar: http://www.metoffice.gov.uk/weather/uk/radar/

North West enlargement (notice on this one pixel on

the Pennines shower band is white (torrential):

http://www.metoffice.gov.uk/weather/uk/nw/...test_radar.html

West Midlands enlargement:

http://www.metoffice.gov.uk/weather/uk/wm/...test_radar.html

Flash Warnings of Severe Weather announced:

http://www.metoffice.gov.uk/weather/uk/uk_...t_warnings.html

These must be very intense downpours if they locally produce 30mm rain!

Edited June 3, 2007 by Thundersquall

[Carl]

Met Office have just updated their weather warnings-

hese are issued when severe weather is expected in the next few hours.

Local areas affected

Warning type

Valid from

Valid to

North East England:

Durham

Heavy Rain 1835 Sun 3 2359 Sun 3

A line of thundery showers is likely to affect the western half of both Durham and North Yorkshire, particularly over the Pennines. Very localised downpours could bring as much as 30mm of rain to a few places. The public are advised to take extra care and refer to the 'Highways Agency' for further advice on traffic disruption on motorways and trunk roads.

Issued at: 1836 Sun 3 Jun

North East England:

Northumberland

Heavy Rain 1839 Sun 3 2359 Sun 3

A line of thundery showers is likely to affect Northumberland during this evening. Very localised downpours could bring as much as 30mm of rain to a few places. The public are advised to take extra care and refer to the 'Highways Agency' for further advice on traffic disruption on motorways and trunk roads.

Issued at: 1839 Sun 3 Jun

Carl

[Stormraider]

Im under that mass of yellows and reds Nwest of Birmingham... been raining about 20 mins now, one or two heavy bursts and a cool W Wind... Doesnt seem to be electrified so far...

[Thundersquall]

This seems to suggest that the convergence has moved further west.

http://www.meteorologica.info/UKstreamlines.htm

I'm suprised those heavy showers over the Pennine area are not thunderstorms

Wow, that convergence between Glasgow and Eninburgh suggest real fireworks as the evening progresses.

East wind meets west in a few locations here which is potentially quite hazardous if the conditions are perfect.

Edited June 3, 2007 by Thundersquall

[Stuart]

I hope I see some storms later this evening

[PersianPaladin]

Met Office have just updated their weather warnings-

hese are issued when severe weather is expected in the next few hours.

Local areas affected

Warning type

Valid from

Valid to

North East England:

Durham

Heavy Rain 1835 Sun 3 2359 Sun 3

A line of thundery showers is likely to affect the western half of both Durham and North Yorkshire, particularly over the Pennines. Very localised downpours could bring as much as 30mm of rain to a few places. The public are advised to take extra care and refer to the 'Highways Agency' for further advice on traffic disruption on motorways and trunk roads.

Issued at: 1836 Sun 3 Jun

North East England:

Northumberland

Heavy Rain 1839 Sun 3 2359 Sun 3

A line of thundery showers is likely to affect Northumberland during this evening. Very localised downpours could bring as much as 30mm of rain to a few places. The public are advised to take extra care and refer to the 'Highways Agency' for further advice on traffic disruption on motorways and trunk roads.

Issued at: 1839 Sun 3 Jun

Carl

Looks better for the likes of Mark (MCS) than me. North-west Durham and Northumberland were my original prediction areas for any lee of pennine developments...(if they should occur).

[Nick F]

This seems to suggest that the convergence has moved further west.

http://www.meteorologica.info/UKstreamlines.htm

I'm suprised those heavy showers over the Pennine area are not thunderstorms

Basically the lapse rates above 850mb over Nern England are unlikely to be steep enough to support t-storms with a layer of realtively warmer drier air aloft preventing upward movement, this is shown on 850-500mb lapse rate charts - ideally you need 25C + lapse rate gradient for storms, the chart shows this is occuring over France where recently cells with sferics have occured over NW France:

12z Nottingham sounding showed this warm dry nose above 800mb and decrease in lapse rate. Even with a convective temp of 24C, cloud tops would still struggle to rise above 400mb, ideally cloud tops would need to reach higher than that for thunderstorms:

There is chance that colder may arrive aloft from the West this evening which may help cloud tops gain greater height, even if it is just heavy showers, as insolation and max heating has all but gone with cirrus infill taking place from the West.