Convective/Storm Discussion Thread 25/5/16 onwards

[Ben Sainsbury]

Is it often to find any MCS where the MCS itself, only have a couple of strikes from it, but were still getting the occasional strikes from this large mass of rain?

[Gordon Webb]

latest news 24 forecast should give william hope as they have showers over the area overnight then a lull with further heavy showers/storms into the afternoon midlands and SE forecast to be in drier slot and dull on E coast with drier further north very similar saturday with showers again focused in south maybe one or 2 further N sunday mainly dry with showers dying then a question mark for mondy of how far west rain gets , thats it in a nutshell

[Staffordshire]

1 hour ago, Costa Del Fal said:

Indeed this was the day of El Brumo. What a stunning event that was. Really quite dark even at 8am in the morning with some of the heaviest rain I have seen and very frequent lightning. I remember the main roads being very quiet as everyone either tried avoiding the storm or pulled over as the rain was so bad!

Yes, it was incredible how dark it went, i often look back and imagine how much more intense it could have been had it not sparked off so early, maybe hitting around 2-3pm.

[Gordon Webb]

16 minutes ago, Staffordshire said:

Yes, it was incredible how dark it went, i often look back and imagine how much more intense it could have been had it not sparked off so early, maybe hitting around 2-3pm.

I also remember that day , got as black as hell and I thought we were in for a pasting fortunately for me if went just to my north and the only time I some anything from that storm was on the news

[William Grimsley]

Just sat in a car park on my way home from Exeter. Lots of Altocumulus Castellanus cloud has come over recently with a heavy downpour visible to the SW. Could be an interesting night. Good luck folks!

@Mapantz, can't wait to see your 'Oops!' look tomorrow!

Edited May 26, 2016 by William Grimsley

[Supacell]

I was chasing across Lincolnshire on the 28th June 2012. The rain was unreal, the heaviest I have witnessed with lots of flashes of lightning.

Nothing of interest for here this weekend but I may have to take a trip down towards the SW if it looks good for Friday/Saturday. 

[Mapantz]

7 minutes ago, William Grimsley said:

Just sat in a car park on my way home from Exeter. Lots of Altocumulus Castellanus cloud has come over recently with a heavy downpour visible to the SW. Could be an interesting night. Good luck folks!

@Mapantz, can't wait to see your 'Oops!' look tomorrow!

haha - It'll be worth it to be wrong, but I'm still not convinced.

[William Grimsley]

Gone very dark here and had some big convective drops on the way home.

[Supacell]

An interesting 48 hours coming up I feel. It is a difficult one to call as there are still big differences between the models. For example, the 06z Euro4 has only the extreme SW and west of Wales affected by showers tomorrow, whereas the GFS has a wide swathe of showers and storms breaking out from London to Wales. Arpege is interesting with a feature running into the SE from the continent tomorrow night. The Netwx version of the NMM shows similar to GFS.

A lot of agreement on showers moving into the SW this evening and overnight but CAPE is rather weak until around the middle of the day tomorrow. Problem with these overnight showers is the chance of leaving behind residual cloud which could hamper the chance of homegrown showers, very much the story of storms in the UK a lot of the time. The CAPE values being shown on GFS are based on a temperature of around 18-19c which will require some heating by the sun to achieve. 

[cheese]

I prefer not to think about 28th June 2012.. sticks in the craw just a little bit, lol. Been quite a few years since the last good storm here.

Edited May 26, 2016 by cheese

[Staffordshire]

I'm aware this isn't really on topic, but whilst we're on the subject, does anyone have any radar grabs from June 28th 2012, or maybe even the animation?

[Ben Sainsbury]

A few lighter showers breaking out over Southern England right now, got my eye on it!

[William Grimsley]

Took this photo of Altocumulus Castellanus cloud looking SE from Exeter:

[Nick F]

Back from a holiday break, so back to looking at convective potential when it arises.

Risk of storms increasing over the next few days for southern areas, as we import increasingly moist air from the near continent, but as always, not everyone will see storms, so some will be disappointed by the potential for the next few days, most favoured areas look to be S/SW England, Wales and increasingly Ireland.

Anyway, risk of some storms developing across S/SW England and Wales this evening and overnight, uncertainty over coverage and eastern extent though. Storms struggling to get far over the Channel now over the cool sea, though further forcing for scent of an increasingly moist airmass moving N out of France tonight and cooling cloud tops may allow storms to develop here.

Storm & Convective Forecast

Issued 2016-05-26 17:05:48

Valid: 26/05/2016 1800z to 27/05/2016 0600z

DAY 1 CONVECTIVE FORECAST - THURSDAY 26TH MAY 2016

Synopsis

Elongated upper low extends from west of Iberia NE toward the UK on Thursday, with a weak cyclonic SWly upper flow across southern UK. Flow veers with height from E to NEly flow at the surface. An area of increasing instability will move N out of N France this evening, bringing a risk of thunderstorms across parts of S England and S Wales.

... SW/S ENGLAND, MIDLANDS and S WALES ...

Subtle shortwave trough, visible on WV imagery, ejecting NE towards NW France this afternoon from the base of upper low to west of Iberia has engaged increasingly moist airmass advecting north over N France this afternoon to produce an area of thunderstorms across Brittany, Normandy and now across the Channel Islands/western English Channel. These storms appear, for now, to be weakening as the cross the cool English Channel ... however, further forcing for ascent of moist airmass spreading north out of N France this evening and overnight may produce mainly elevated thunderstorms across the above areas - particularly in the early hours as cloud tops cool. Vertical shear will be weak, around 20-30 knts, so no severe weather anticipated, though enough shear  for some multicell clusters that may produce locally heavy rain that may lead to flooding, gusty winds, hail and frequent cloud-to-ground lightning. There is some uncertainty over eastern extent of storms moving N and NE - with SW England and S Wales currently at greatest risk, though isolated storms can't be ruled out further E and NE.

DAY 2 convective outlook for Friday 27th May will be issued later this evening

[William Grimsley]

Hello there! http://estofex.org

[Ben Sainsbury]

2 minutes ago, William Grimsley said:

Hello there! http://estofex.org

Level 1 it's a miracle!

Valid: Fri 27 May 2016 06:00 to Sat 28 May 2016 06:00 UTC

A level 1 was issued for SW UK mainly for excessive rain and isolated large hail.

Somewhat weaker CAPE and DLS still support at least temporarily organized multicells during the forecast. Large hail and strong to severe wind gusts will be possible and an isolated tornado event can't be ruled out, especially during the late afternoon/evening hours, when LCLs drop to 800 m or less. Widespread activity could support a few cold pool driven line-ups with a more concentrated severe wind gust risk, but this will be heavily dictated by the mesoscale. Finally, slow storm motions and clustering storms increase the excessive rainfall risk at least on the local scale. This is especially true over S-UK.
During the night, a slow weakening trend is anticipated, but troposphere remains still supportive for scattered thunderstorms with isolated large hail and excessive rain.

Edited May 26, 2016 by Ben Sainsbury

[William Grimsley]

Just wondering if this is actually going to effect me or whether I'd have to go all the way to N Devon again. Not sure why there's nothing issued for tonight. Anyway...

Just checking in on that cell over the Channel Islands, seems to be intensifying on the western edge, maybe it's that lovely forcing that Matt was on about...

Edited May 26, 2016 by William Grimsley

[William Grimsley]

1 hour ago, Ben Sainsbury said:

Is it often to find any MCS where the MCS itself, only have a couple of strikes from it, but were still getting the occasional strikes from this large mass of rain?

I'd say not, that would mean the stuff to the south would be an MCS... LOL.

Also, still looking at that Channel Islands cell, I can see at the surface the motion is more westerly whereas higher up it seems to be more NW'ly, that's quite a bit of shear... But, even so, I'm struggling to see where these thunderstorms are going to originate from. Do we need to clear the crud left by the thunderstorms first? I'd presume not as MLCAPE is now taking over from SBCAPE.

Edited May 26, 2016 by William Grimsley

[Milocation]

looking fairly clear, hoping that the French storm makes its way up here

[Mesoscale]

10 minutes ago, LimoPreacherman said:

looking fairly clear, hoping that the French storm makes its way up here

Haha wishful thinking? 

[Milocation]

8 minutes ago, Mesoscale said:

Haha wishful thinking? 

gee thanks!

[Tim Bland]

Current storm is heading North East towards Belgium ....

 

[Supacell]

I finish work at 1pm tomorrow and it is looking increasingly likely that I will be heading in a SW direction afterwards

[Gordon Webb]

34 minutes ago, Supacell said:

I finish work at 1pm tomorrow and it is looking increasingly likely that I will be heading in a SW direction afterwards

seems an easy decision as the showers/storms will be focused over the SW portion of the country and that goes for this evening and overnight as well even though the midlands is mentioned in some forecasts the chances of that are very minimal indeed I suspect , not that I'm having a go at any forecaster just in case my comment is taken the wrong way

[East_England_Stormchaser91]

7 hours ago, Harry said:

80 strikes in 20 mins??? Pah! That's nothing old bean - remember this event from last year? This was kicking out about 80 strikes per minute  

The things I'd do to see a similar event this year. Here's what I got from that night!