Storms and Convective discussion - May 2024

[Daniel Finch]

 Mark Parsons

[Sam jackson88]

 *Stormforce~beka* true but can always hope XD

[viking_smb]

 Thunders  when i was in school back in late 90s early 00's, I had double science (top of class in chemistry), PSHE, PE, maths and english/eng lit, welsh for some bizarre reason ( I didnt even turn up to the exam as didnt see the point), and RE which i found boring

Options wise I took IT (back then we had windows 3.1 and windows 95/NT), Design tech resistant materials, geography and travel + tourism, 

 

back to the weather I think it will be mostly kent way that will have the storms.

Edited May 1 by viking_smb

[*Stormforce~beka*]

 Sam jackson88 I'll be here on and off til midnight 

[Purplepixii]

 *Stormforce~beka* & @Sam jackson88 howdy neighbours, funny we’re all here again lol! Still think we should move to Kent though.

[Eagle Eye]

Convective Outlook (tomorrow afternoons risk to come tomorrow) ️ 

An upgliding theta-E ejection on the east side and parallel to a northwestward moving warm front should allow for an MCS to approach the south coast overnight with Supercellular activity possible mainly with feeding cells on the eastern side of the storm. Frequent lightning, 40,000 feet tall storms, some severe hail and some flash flooding are all possible.

 

Linear development should take place after initial surface development over France evolves from surface to elevated during the evening. With dry warm air, or on slightly less capped models a warm nose, intruding at the 925hPa level, a surface inversion layer forms and without surface heating as night falls, convection is very likely to transition to elevated well past the boundary layer where significant ascent begins to be forced with the development of stronger lapse-rates and a potential vorticity lobe stretches out to help with development into a full on linear MCS.

 

As it hits the south coast, the far eastern extent of the MCS may develop more significant potential with slightly lower LCL’s and energy pushing in more from the southeast into the Kent and Sussex coast generally on most but not all models. Some models have the eastern extent a lot further west between Brighton and the Isle of Wight, but those models are beginning to become outliers compared to most. This is where 3000+ J/KG of MUCAPE is possible for the development of these cells and the eastern extent is more likely to see frequent lightning given more depth of MUCAPE and more MUCAPE generally. 

 

The movement from northern France is northwest towards the central south to be hit first by the first part of the MCS but that appears to split or attempt to detach from what becomes the main MCS and weaken over the channel as it gets embedded into the warm front but may remain as thundery rain. That is not the main risk and occurs late in the evening. It is also not guaranteed to become much and may just be a feature of the warm front itself.

 

Whereas the overnight risk comes next with MCS development further SSE, orientated less parallel and more head on towards the south coast moving northwestwards from northeastern France andor Belgium towards the central southern and southeastern coasts. Then it should move NW and further inland towards southern parts of the Midlands. With very lightning favourable saturation and significant MUCAPE, likely 1500-2000+ J/KG and cloud heights possibly up to 12km as it appears likely to hit central southern and southeastern coasts. This is where most risk comes from. The AROME and UKV are very strong on this occurring with pre-MCS cells forced with the change in wind direction forcing wind convergence in a line between Belgium and the SE on a few models and if this does occur, then very strong energy is available for pre-MCS cells to form and frequent lightning is very much a possibility along with severe hail especially as it eventually combines with the MCS.

 

The most unstable buoyant layer has lifted indexes of around –9, which is extremely rare for UK risks and show the vigorousness of convection, hence the only reason why this isn’t a high risk is because of the worry over where the MCS hits. It would be in the SE but the Swiss models refuse to back down and they have been some of the best models, instead they focus on the central south with some convection extending east past Kent once it gets towards London way.

 

A large inflow layer with significant energy and large buoyancy means that despite strong low-level shearing, hail is possible between 1 and 1.5 inches. This especially evident where cells feed momentum where they combine or if a Supercell does form. Rainfall totals could also be fairly upwards of 30mm in places and a lot of that falling in a short amount of time with a lot of moisture available. Therefore there exists risk for flash flooding.

 

Overnight, initiation may occur north of the MCS as a forcing band develops perhaps due to gravity waves as the very tall potential of these storms gives that risk. Similarly, storms could trail behind to the south and east if the MCS is particularly strong enough. Some of which may last well into the morning because of the significant energy available.

 

Eventually it should weaken wherever it is around 4am to 6am into thundery rain. This is where the potential weakens and any trailing cells are the main risk but only really on the UKV.

 

There is still a lot of difference between the models but frequent lightning they almost all agree on. Along with some severe risk and generally quite significant storms. Along with the upscaling into an MCS at least of sorts on pretty much all of the models.

[CoventryWeather]

Do wonder if the storms over the Dutch German border are possible developments to watch tonight. Know they are surface based, but could develop storms around them as they approach the southern north sea..

[Thunders]

Coffee #1 made and now being consumed 

[Biggin]

Fair bit of activity over w Germany / e netherlands atm. Blitzorturong:

 

[ChannelThunder]

I'm not a mod, but if people can refrain from using the word 'bust' (if actually applicable) until at least the scheduled time of the storms, that'd be great! Just a little pet peeve from previous recent events...

[Thunders]

 ChannelThunder fr

[Thunders]

With the storms over Germany, here are the reflectivity and velocities 

[SilverWolf]

 ChannelThunder Agreed.. some of the best weather I’ve ever experienced (be it snow, storms, whatever), ‘predicted’ or otherwise, have occurred very quickly, often within  less than a couple of hours of radar watching. As you a say a ‘bust’ should be during or after an event, and even then just 20 miles down the road can often be epic during a bust. 

Edited May 1 by SilverWolf

[StormLoser]

I wish you all happy storm watching! Me? Storm Loser took the train to Durham to see his elderly mother. Family comes first. The day after I arrive, all the action starts....   How typical is that!  Anyhow. I will watch from afar. Enjoy!

(Breaks down in tears...)  

[Thunders]

[*Stormforce~beka*]

 Purplepixii I'm on the way ... I'll pick Sam up then you after. That said ... I don't drive so I'll be on the train  

[ChannelThunder]

 SilverWolf exactly! I've seen the word brought out on here prematurely, shortly before Blitz has then litten up! Obviously every situation is a bit different, but it can't be called a bust until it's actually appropriate to do so based on timings and severity on model runs and outlooks.

[*Stormforce~beka*]

 ChannelThunder what time are we looking at near our location?

[matty40s]

For the unexpected, keep an eye on the east of Northampton, north of Milton Keynes....massive clouds going up, out of warning area, but humidity is currently 95% and there is plenty of sunshine to drive it.

[Metwatch]

Briefly spitted just now. Flow is coming in from the south east and it became lighter from the east after the shower passed rather than from the west during the majority of the time here. Light levels were really poor for a moment, a bit funky. I think that often happens when it's hazier than usual and any showers amplifies the darkness (hence you get daytime darkness events during much stronger storms with dustfalls i.e July 1968). This afternoon specifically reminds me a little of April 2019, one of the days that month which brought some decent thunderstorms around here, that also came in from the south east, might have been the 8th. I do wonder if some dust is being brought up given the pattern.

Regardless it's nice for this month to start off feeling quite seasonal, 17-18C sunny spells earlier but also hazy and a little humid. I guess since it's been quite cool up until the last few days, this exact same humid air will feel warmer than it might do if it was in September following summer; acclimatization.

 

Edited May 1 by Metwatch

[ChannelThunder]

 *Stormforce~beka* 1-2am by looks of it. Latest Arome is far from encouraging down here though...

[Frosty hollows]

 Biggin Yep . They've been getting quite the show all afternoon!

[*Stormforce~beka*]

 ChannelThunder I won't bother staying up then! Thanks 

[Rufus Butterfield]

Seems to be an interesting feature shown for Friday morning for Lincolnshire and areas further west, not sure how thundery it will be though.

[Eagle Eye]

Current developments suggest the central south and slightly further west than most models are in with a shout but Belgium is well on course as well. Hopefully this continues to evolve.