Storms and Convective discussion - 20th March 2023 onwards

[Eagle Eye]

8 minutes ago, East_England_Stormchaser91 said:

Wow, that must’ve been spectacular. Most of our amazing storms here are governed by the dynamics in the elevated layers. 
Correction from earlier post, it must’ve been April 2005 when those storms passed through! Just looked at the charts archive! Was a very good setup indeed. 

The thing is that tomorrow is a cold front setup for the plume. It's a relatively dry warm nose ridge above the moist low-levels causing 'crud' lasting throughout most of the day I would imagine though for the SW that's less so with the diffuse cold front having passed in the morning  and then the secondary cold front acting like an occluded front with lifting and maybe more in the way with clearings of low-level cloud though I haven't seen the saturation forecasts yet. So it occurs on the boundary-layer cold and relatively warm SST's compared to the quite strong cold front and so the buoyancy increases very quickly from a quite suppressed atmosphere throughout the day. Not sure whether the speed of it being so strong would increase the buoyancy more than the models are showing but that might be a possibility. The thing is as always timing with the cold front and the open cold sector for the boundary-layer and above and whether that can manage to clear across the SE in time for the advection of lifted moisture to be more like recent UKV and AROME runs for the evening or whether most models are correct in confining the open sector to the SW and maybe towards the central south and moving slightly to the north. I will say this though, most CAM's tend to 'overcloud' and this setup relies heavily on the amount of cloud being low so it might be good that they are showing something for us. Alternatively, they could be being overprogressive.

[Metwatch]

34 minutes ago, LightningLover said:

15th April 1981 was also spectacular apparently (was only a twinkle in my mum's eye then); Warm uppers were advected WNW from France by high pressure, with a resultant prolific mid-level lightning show... But interestingly  only 5-7c at the surface here with fog and a keen NNE breeze!! 

Certainly an interesting case study! Surface flow with a chilly Northeasterly but at 500hpa a south Easterly flow!

[ChannelThunder]

A much more toned-down UKV this morning, which feels more realistic compared to the torrential thunderstorms shown yesterday! All of the outlooks are in agreement with parts of Ireland/NI and SW England being the best spots for any organised thunderstorms.

[Harry's House]

11 hours ago, LightningLover said:

Distinctly rare, but entirely possible to have more organised thunderstorms in Late March- I believe 23rd March 2005 was a great example, when elevated thunderstorms formed on the periphery of mild air being wafted up by a deep trough out west... 850's were only around 6-8c, but it did the job! Obviously they weren't May-September grade storms, but still!

On 23rd March 2005, I was living in Bulford and working at Larkhill, near Amesbury. The elevated storm was quite living during the late evening of that night. There had been thundery activity over Spain earlier.

[LightningLover]

6 minutes ago, Harry's House said:

On 23rd March 2005, I was living in Bulford and working at Larkhill, near Amesbury. The elevated storm was quite living during the late evening of that night. There had been thundery activity over Spain earlier.

Yeah I was meant to say, I got my source on that one from you a long while back in a different thread! Thanks for that  

[ChannelThunder]

Looking like a case of: I charge my camera batteries: nothing happens. I don't charge them: an elevated thunderstorm develops on the southern flank of the broader heavy rain moving NEwards this evening and tracks over the IOW and Hants/Sussex.

 

[alexisj9]

3 hours ago, ResonantChannelThunder said:

A much more toned-down UKV this morning, which feels more realistic compared to the torrential thunderstorms shown yesterday! All of the outlooks are in agreement with parts of Ireland/NI and SW England being the best spots for any organised thunderstorms.

There will be no day times storms here lol, but there was never going to be, we low cloud type fog.

[A Face like Thunder]

.... but be prepared to batten down the hatches along the Channel coast on Thursday / Friday. Yellow weather warning  for wind to 12noon Friday now issued.

[ChannelThunder]

Some meaty looking cells with apparent hail cores bearing down on Belfast, although no lightning being detected:

[ChannelThunder]

...and they're off!

Edited March 29, 2023 by ResonantChannelThunder
Duplicated post

[Guest]

46 minutes ago, ResonantChannelThunder said:

...and they're off!

And they've stopped.......

[LightningLover]

12z UKV brings back some interest for Sussex/Kent dwellers for around 20:00-21:00; Some seemingly elevated showers/storms forming just ahead of the cold front boundary.

[ChannelThunder]

59 minutes ago, Alderc said:

And they've stopped.......

I'll take the blame!

[Jamie M]

Lovely stuff.

[Eagle Eye]

Convective Outlook ️

Thu 30 0100 - Thu 30 2000

In England a shortwave trough behind a clearing cold front will provide instability in band's of converging vorticity most likely in the slight risk area in England. Similar in Ireland and parts of Scotland but behind an occluded front with no real shortwave trough just based off surface heating.

Surface heating is likely to yield 700+ J/KG of SBCAPE and given cloud clearing as the edge of the cold sector leaves around 2PM across England favouring kinematics in areas of convergence. An AOI has been added in the most supportive area for the strongest pulse storm organisation favourable for lightning.

Around midday though further west of the AOI is when storms are likely to fire. Given increasing buoyancy and heating though mostly pulse-type with little-shearing mostly based in the low-levels but no real hook expected.

Compared to previous events recently, saturation is unlikely to be a problem and is rather modest though I suspect given surface-based convection hefty downpours with the best conditional PV towers.

Lightning may organise best in the AOI given slightly better shearing and not over-saturation.

Interestingly, lapse-rates look to be very steep with cold upper air and surface heating allowing for them to steepen as the day goes on and that really supports good updrafts for hail a couple CM's big.

An almost entirely similar risk in the other slight so I feel very little need to go into more depth.

So most support is for sporadic lightning, organising for a time potentially, hefty downpours and some hail.

[ChannelThunder]

Starting to look very blocked towards the end of next week. The sort of block that doesn't budge in a hurry. Could be a very quiet start to the season in this thread.

[Rufus Butterfield]

Driving test tomorrow; hopefully won’t get caught in a downpour.

[Eagle Eye]

Last night photo dump.

What would've been a good photo if it weren't for the time.

I know this is the convective thread but just had to share this

And a couple time-lapses.

 

 

[BlueHedgehog074]

Some lovely shots, Eagle Eye. Particularly of the Mammatus cloud. What a big blanket of it you had! The motion of it was interesting too.

[Windblade]

14 hours ago, Jamie M said:

Lovely stuff.

Typical. Stops sparking as it approaches me and then starts again once it's past and out of range! 

[Arnie Pie]

A slight chance today

https://www.youtube.com/watch?v=Zl7EDcyizmY

 

[Metwatch]

Small time-lapse of some attempts at decent convection this afternoon, some pretty high wind shear and fast paced mid level winds today.

850hPa flow at around 40mph from the latest GFS run for midday. 

Edited March 30, 2023 by Metwatch

[toggerob]

14 hours ago, Rufus Butterfield said:

Driving test tomorrow; hopefully won’t get caught in a downpour.

Good Luck! let us know how you got on.

We had one rumble of Thunder in Buxton at 12:37pm this afternoon after a deluge lasting some 30 mins, roads instantly turning to rivers and traffic slowing down to a near-crawl. Unfortunately I was running some work errands so wasn't able to 'storm chase' or pull-over to take some pics, but at least I was in the middle of the fun.

[Eagle Eye]

Small chance that this produced high precipitation Supercellular characteristics for a few minutes earlier. Supported by the hodographs around the area from the GFS forecast slightly.

Supercell favourable tends to be straight strong deep-layer shear. Multicellular tends to be diagonal deep-layer shear. You can see its quite weak and in-between the two.

Edited March 30, 2023 by Eagle Eye

[Rufus Butterfield]

1 hour ago, SNOW_JOKE said:

Good Luck! let us know how you got on.

We had one rumble of Thunder in Buxton at 12:37pm this afternoon after a deluge lasting some 30 mins, roads instantly turning to rivers and traffic slowing down to a near-crawl. Unfortunately I was running some work errands so wasn't able to 'storm chase' or pull-over to take some pics, but at least I was in the middle of the fun.

Passed it! It did chuck it down at one point, but it was brief.

Edited March 30, 2023 by Rufus Butterfield