Storms and Convective discussion - 1st May 2022 onwards

[TJS1998Tom]

Hoping later this month there's some thundery action with all this cloud being in the way, unless we get something in the morning

 

[sunnijim]

The heads have blown off the French cells and sent the sun in here.

The sky does look to be reminiscent of pre storm skies down the years....

Can be somthing of a guide rather than model watching and radar disappointment as the current French mass looks to just disintegrate as it starts crossing water.

It maybe after midnight that conditions become ripe for developments nearer our shores.

Edited June 4, 2022 by sunnijim

[Dami]

Grey over the channel 

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[Azazel]

Feeling really quite juicy out there in the sun and some solid towers going up to my south 

[sunnijim]

22 minutes ago, lottiekent said:

Exactly what I was saying earlier. Was warm earlier but the wind has just gotten stronger and stronger. It’s only 15.4c outside now!

Just driven back to Brighton from SE London.

Have noted some wild fluctuations in Temperature,

21c SE London.

Just before Clacket Lane on the M25 13c under heavier cloud.

20c as I approached Brighton.

[sunnijim]

2 hours ago, Lance M said:

UKV has certainly struggled to get a grasp of this event, with several different evolutions of what may occur over the last 48 hours.

Here we go again with a different outcome, but a very interesting one it has to be said:
 

I don't want to spam the place with too many images, but remember that UKV charts are available for free now here if you didn't know  : https://www.netweather.tv/charts-and-data/ukv

 

After saying a little earlier that I didn't want to get too hung up on models,

The irony of that set of charts isn't lost on me.

I often seem to be overseas when thunderstorm classics hit Brighton.

Could it be that I have just left the SE London storm zone in favour of my other base on the South coast.

You betcha

Edited June 4, 2022 by sunnijim

[Harry]

Not overjoyed at that mass crossing the channel. As pointed out by @staplehurst and others, that could serve to spoil the atmosphere later tonight 

[Petorious]

6 minutes ago, Harry said:

Not overjoyed at that mass crossing the channel. As pointed out by @staplehurst and others, that could serve to spoil the atmosphere later tonight 

Hard to tell at moment, though the fact its all going to happen with nocturnal cooling creating the storms, the mass of high cloud coming from the south may not effect things for later, at least that's what I've been lead to believe? 

[Flash bang flash bang etc]

Isn’t a trough supposed to be the main initiator later this evening around 00:00 ?

People getting too excited about the stuff in the channel - it’s gonna burn itself out I think. Eyes to the turn of the night - that’s when things could get interesting… and very, very damp

[StormLoser]

Why do I get an uneasy feeling this isn't going to work out?  I'm not going to call it a (unmentionable 4 letter word of total disappointment popular in this Forum) but... 

I'm not feeling the potential over southern UK. A lot of the earlier unstable cumulus has vanished from here and I could be forgiven for thinking it is March.

I do hope I am wrong.  And as for a trough...ermmmm...

Edited June 4, 2022 by StormLoser

[Turquoise]

Personally I think the French storms at moment are not the event we are anticipating. I think surface based violent storms will shoot up inland around CS/SE within next few hours and slowly track north, probably turning to rain only around midnight by the time it reaches the Birmingham area and northwards 

[Flash bang flash bang etc]

1 minute ago, Azuremoon2 said:

Personally I think the French storms at moment are not the event we are anticipating. I think surface based violent storms will shoot up inland around CS/SE within next few hours and slowly track north, probably turning to rain only around midnight by the time it reaches the Birmingham area and northwards 

Just a tiny bit of wishful thinking, perhaps?

[Turquoise]

Just now, Flash bang flash bang etc said:

Just a tiny bit of wishful thinking, perhaps?

Hmm perhaps. All the ingredients are in place, just needs one to start popping off but with this set up it's hard to predict especially with varying models

[ChannelThunder]

A cell has popped off over the sea to the southwest of Jersey, indicating that we can expect elevated developments over the water from now on.

[lottiekent]

1 hour ago, sunnijim said:

Just driven back to Brighton from SE London.

Have noted some wild fluctuations in Temperature,

21c SE London.

Just before Clacket Lane on the M25 13c under heavier cloud.

20c as I approached Brighton.

Down to 14.7c now and fully clouded over

[alexisj9]

1 hour ago, Jamie M said:

Shearing on those cells over France are impressive with lots of cirrus spilling into the SE.

Good map above shows the level of shear in France at the mo! 

Means while it's now overcast here due to those storms. Believe it or not, quite active in the channel on the French side.

[Guest]

Latest UKV indicates a 12am-1am initiation in the SE for storms tonight. Forget the ones currently over the Channel Isles.

Destabilisation for us occurs later tonight.

[sheikhy]

7 minutes ago, Steel City Skies said:

Latest UKV indicates a 12am-1am initiation in the SE for storms tonight. Forget the ones currently over the Channel Isles.

Destabilisation for us occurs later tonight.

Mentioned this earlier!!!!i think our storms are forecasted to erupt across southern england!!!

[alexisj9]

An obvious bow echo Infront of the rain now showing in parts, this will blow out soon.

[Josh Rubio]

Think some people need to look closer to home rather than looking over the pond 

[staplehurst]

I've seen a few posts about it not "feeling stormy" or "warm/humid enough" for storms. That's the beauty of elevated thunderstorms - it can be as cold as you like at the surface. In some ways, the colder the air at the surface, the more 'forced lift' potential should a warm airmass be pushed northwards towards the UK (because warm air will be forced over a layer of colder, denser air, creating ascent). Ultimately thunderstorms have little interest in whether we think it's warm or cold at ground level, because it's all about relative temperatures rather than absolute. That's how you get thunder snow in the winter! 

The idea behind elevated thunderstorms is that they can be partly driven by a process called isentropic lifting/upglide, which in a nutshell is where warm, moist air is forced up over a cold, dense airmass near the surface. This is common in the warm season over the English Channel and southern England, and is often responsible for our overnight "plume" thunderstorms. I've modified this vertical cross-section of Theta-E to hopefully give a better idea of the lifting of the warm air as it moves further north...

 

The 12z sounding from Trappes unmodified yields 1,700 J/kg CAPE but it is capped by a warm nose at 850-900mb. However, the cap is small (20 J/kg CIN) and easily eroded by surface heating which is what we've seen over France this afternoon. If you modify the sounding to representative surface temperatures and dew points then you're left with explosive deep convection with 2,500 J/kg CAPE. These storms are surface-based, and so as soon as they dip their toe in the SSTs of just 13-15C in the English Channel then they're not going to respond too kindly and will likely decay (with lightning largely staying over the Continent).

 

The big issue with France getting all excited is it completely washes out the atmosphere in that area and significantly modifies the thermodynamic profile. The 12z AROME picks up on this signal, with a large pool where CAPE has been used and the atmosphere is much more stable.

However, the air over the English Channel (especially near the south coast) and across southern England is still relatively unstable, as confirmed by the earlier 12z sounding from Herstmonceux which yields 350 J/kg CAPE from parcels lifted from the ~830mb layer (if you could lift it from the warm nose at the ~920mb layer there would be much more substantial CAPE). You can also find convergence generated by outflow from earlier French storms can (perhaps temporarily) provided an uptick in elevated convection on the leading and/or western edge of the broader precipitation shield.

An elongated PV strip stretches currently from northern France across Biscay down to northern Spain, and the leading edge of this is likely driving the storms near the Channel Islands. So in the short term, it is this area that is likely to produce active thunderstorms, the focus shifting slowly towards Cen S England. However, as the PV strip eventually reaches the south coast, it will likely engage more with the residual instability 'tongue' late evening/towards midnight and this is when model guidance suggests a fairly rapid increase in elevated shower/thunderstorm activity over central southern England. That said, they are naturally struggling with the earlier French convection (no surprise!) and how that may impact things tonight. It seems, because the French exports are so slow moving (due to weak steering winds) that this may not hamper things too much across S/SE England later tonight - but those locations on the coast it is very much dependent on how quickly things can initiate before the instability plume moves inland. An interesting evening/night to come either way!

Edited June 4, 2022 by staplehurst

[Rufus Butterfield]

Arrived in Bedford now, hoping for something tonight 

[Zak M]

2 minutes ago, Rufus Butterfield said:

Arrived in Bedford now, hoping for something tonight 

Fingers crossed eh. 

[AnvilCrawlers]

I'm just wondering if the cell around jersey can hit us in Somerset.thats best hope I think we will get here.

[ChannelThunder]

18 minutes ago, staplehurst said:

I've seen a few posts about it not "feeling stormy" or "warm/humid enough" for storms.

The same posts happened before the May events, too! Seems they're always going to happen unless it's > high twenties!

Thank you for the detailed update! Good to know that the instability is still there for the central South.

Edited June 4, 2022 by Lance M