Storm & Convective Discussion - 1 September 2015 onwards

[Cloud 10]

A few more strikes showing up now which is a bit un-expected.

 

[Summer Sun]

Rumbles of thunder and heavy rain over Darlo

Edited September 12, 2015 by Summer Sun

[Gorky]

Cracking storm in Scarborough at the moment. Constant thunder... hail over half an inch across and serious amount of rain... Car alarms going off on my street!

[Beverley Lass]

Yes, I heard frequent thunder about 15 mins ago, but we missed the storm really, no rain.

 

B.

[Condor Vitesse]

Cracking storm in Scarborough at the moment. Constant thunder... hail over half an inch across and serious amount of rain... Car alarms going off on my street!

Great day for the Goldwing parade!!!

[Gorky]

Quick vid.. Can't here the thunder over the noise of the rain on the porch roof though :/

 

Edited September 12, 2015 by Gorky

[Winter Cold]

Glad the east coast got something today at least. Shame you can see all that lightning being wasted now out in the north sea    typical!

 

I took this pic just now of the big shower passing north of Sheffield

 

Edited September 12, 2015 by Winter Cold

[mike57]

Had a storm down the coast at Bempton at about 15:30 lasted about 15 mins, nothing like the Scarborough one, but heavy rain for 10 minutes, a number of C-C flashes, didnt see any C-G. There seemed to be some disoragnised rotation and some very gusty winds, would have chased it but was heading off into the North Sea. Some after storm pictures below

[Mokidugway]

Convective cloud building now .

[Flash bang flash bang etc]

Will be watching this cam later (if I'm awake at the time!) - it's where we were for our summer hols and heavy storms predicted after midnight tonight. Great streaming view of the harbour and in the general direction of said storms:

http://www.sanarysurmer.com/la-Webcam-de-Sanary

[Summer Sun]

Wednesday doesn't look a good day at all heavy rain for most parts at some point during the day and strong to gale force winds for some

 

[alexisj9]

Wednesday doesn't look a good day at all heavy rain for most parts at some point during the day and strong to gale force winds for some

 

Had lightening down here in the SE on our local forecast for wednesday. 

[Greeny]

Monday is still looking interesting, although shear is pretty weak, the centre of a low is forecast to cross England according to GFS and the metoffice fax chart which brings some convective potential and steepened lapse rates for the country. Then winds at the surface pick up from Monday evening in some places.

 

Edit: I just noticed on the NMM that a wind convergence zone sweeps northeast from southwest England to central England by 21z which could be the trigger for storms if surface heating is slack. Still have tomorrow to go through yet though so could change before Monday.

Edited September 12, 2015 by Greenday

[East_England_Stormchaser91]

Off topic a bit, but check this amazing lightning show going on just off Marseille!!

 

http://www.viewsurf.com/univers/plage/vue/13870-france-languedoc-roussillon-marseillan-live

Edited September 12, 2015 by East_England_Stormchaser91

[Flash bang flash bang etc]

Off topic a bit, but check this amazing lightning show going on just off Marseille!!

 

http://www.viewsurf.com/univers/plage/vue/13870-france-languedoc-roussillon-marseillan-live

Oh poo stripes, I slept right through and missed it. Was watching on radar last night and it looked awesome and there's a lot of great quality cams for that area. I think this is a good time of year for those coastal towns because of convergence and temp differences so the storms can be huge - and like last night they can last for hours!

On a slightly connected note I have a slo-mo video of a multi-forked CC lightning bolt from our holidays to Sanary but - and here's the unusual thing - normally you see the strokes weaving through the air but these were so fast they were there one frame and not there in the next - and this was at 750 fps!

It seems to me it was a completely different form of lightning altogether!

I'll upload the vid if I get time today...

[Nick F]

Off topic a bit, but check this amazing lightning show going on just off Marseille!!

 

http://www.viewsurf.com/univers/plage/vue/13870-france-languedoc-roussillon-marseillan-live

 

Yes, some strong multicell storms training along the Cote D'Azur overnight and still this morning, generated  by the upslope feed of air off warm Med waters and helped by an upper trough drifting east seen by dark stripe on WV imagery. Would love to be there watching these out to sea!

 

Satellite and radar

 

WV imagery this morning:

 

Risk of supercells and muticell storms training along the Med coast of NW Italy/Gulf of Genoa today - which could bring excessive rainfall amounts and a risk of flash flooding. Estofex have a Level 2 for the region with talk of 3K CAPE close to and over the Med with potential for 300mm falling in places helped by the orographic forces along that rugged coast:

 

http://www.estofex.org/

 

Already we've seen deadly floods further south over southern and eastern Spain early last week and flash floods in Sicily too mid last week. Mediterranean SSTs, particularly the western Med, seem to be above average this year, which seems to be fuelling powerful supercell storms and MCSs when the right conditions come along.

 

Closer to home, looks like an interesting few days coming up with low pressure systems queuing up to attack us from the SW, particularly as some potent shortwave troughs with quite cold air contained in them drop SE from the southern tip of Greenland and interact with these lows that have Tm air wrapped up in them. GFS develops some reasonable CAPE across southern Brtiain on Monday in the rPm airmass and again on Wednesday ahead of a deep low moving up from Biscay that formed from the remnants of ex-tropical depression Henri.

Edited September 13, 2015 by Nick F

[Flash bang flash bang etc]

Looks like a potential storm feature is possible that would move up NEwards tomorrow morning from the channel through Hants, Surrey and into London (based on clues picked up from various sources). I don't know how potent but the word 'thunderstorm' is actually quite a vague term here in the UK and it could mean a flash and a bang or something a bit more significant.

Either way looks like even at work I'll be in the path of some reasonably exciting weather.

Also looking good down near the coast in Portsmouth area for weds but a long way off and my forecasting method isn't based on direct model reading which probably makes it quite inaccurate.

Either way a good week for weather coming up so I'm excited :-)

[Rain123]

Looks like a potential storm feature is possible that would move up NEwards tomorrow morning from the channel through Hants, Surrey and into London (based on clues picked up from various sources). I don't know how potent but the word 'thunderstorm' is actually quite a vague term here in the UK and it could mean a flash and a bang or something a bit more significant.

Either way looks like even at work I'll be in the path of some reasonably exciting weather.

Also looking good down near the coast in Portsmouth area for weds but a long way off and my forecasting method isn't based on direct model reading which probably makes it quite inaccurate.

Either way a good week for weather coming up so I'm excited :-)

Good. We need some exciting weather round here.

[Supacell]

Potentially good thunderstorm set up for tonight and more especially tomorrow. It does require a few parameters to fall favorably though for the best of it to be realised.

 

Tonight it looks like an increase in CAPE close to the south coast and just inland from here from around 00z onwards. This could promote an increase in thundery activity during the early hours within the showers that will tend to run into the south as a developing area of low pressure moves up from the south-west with an occluded front pushing north. Wind shear is weak and so organised thunderstorms are unlikely but I would not be surprised to hear some reports of thunder even before dawn tomorrow.

 

 

It is into tomorrow that my interest increases as some decent SBCAPE develops and expands from the south into a good proportion of England and Wales south of N England behind this occluded front. Euro4 seems to indicate scattered convective cells developing within this post frontal zone and moving slowly north through the morning invigorating along a line moving northwards through the Midlands in the afternoon. Currently the best of the instability remains ahead of any deep layer shear though and this would reduce the possibility of anything organised but low ELT's, CAPE in the region of 300-500j/kg and decent lapse rates may allow for some electrically active pulse type storms running north with this line. 

 

 

The line is marked by an area of wind convergence and this could promote the chance of storms organising along this line.

 

 

There is a lot of moisture available within a humid TM airmass and this could mean some torrential downpours with a lot of rain falling in a short space of time. It may also work to limit convective potential though as extensive cloud cover may scupper chances during the day.

 

 

 

Showery rain moving into the south coast this evening has the potential to contain some convective and weakly thundery cells during the early hours. This moves northwards through to northern England by midday/early pm tomorrow as a weakening feature. 

 

Behind this a few heavy showers could break out along a convergence zone and push northward through CS England and into the Midlands through the day to sit across N England by evening (WRF moves this through a little slower and thus it does not get as far north as on GFS). Should there be any surface heating this is likely to promote thunderstorms to develop as it pushes northwards and these could focus across this convergence zone. Extensive cloud cover and thus lack of surface heating could prevent cloud tops attaining the required height for storms. Any thunderstorms that do develop could be quite electrically active at times but will likely be of the pulse type variety.

 

Should surface heating occur and shear overlap instability and convergence then this could allow for more organised and possibly severe storms, although this looks unlikely looking at the current suite of charts I have seen.

 

[Winter Cold]

Thanks for that Supacell, ill be watching with interest tomorrow then! Hope we get something decent. Maybe a day to set the timelapse up in the afternoon anyway

[Costa Del Fal]

Wednesday just looks like the usual SE takes all event now.

[Paul]

For our extra subscribers, we have a 500 metre rainfall radar available now:

 

https://forum.netweather.tv/topic/84002-new-500-metre-rainfall-radar-first-look/

[Flash bang flash bang etc]

Wednesday just looks like the usual SE takes all event now.

Wasn't it always gonna be like that?

[I remember Atlantic 252]

Wasn't it always gonna be like that?

 

Yes it was, thunderstorm wise

[Maxum]

met office have warnings out now 

 

For Monday 

 

 

http://www.metoffice.gov.uk/public/weather/warnings/#?tab=warnings&regionName=se&fcTime=1442185200