Ben Sainsbury

The explosive development of the storms along the south coast, look very impressive on the Sat24.

Just for fun of course, but home-grown MCS anyone?

Can you elaborate, I'm not sure that I know what you mean?

That time again for thunderstorm activity is upon us, let's take a look at how things are shaping up for tomorrow. General consensus is for CAPE values to reach between 400-500J/kg in some of the more favourable locations tomorrow, severe parameters look relatively limited for tomorrow so no severe potential unfortunately. Saying that there is a possibility of seeing a FC or two tomorrow given decent LLS and wind convergence zones. Convergence zones along with strong heating look to be the prime factor for initiating storms and these are evident across much of East Wales/Central Areas along with parts of Dorset into Devon. Storms moving SW throughout the day and evening. Beginning with the GFS: As always CAPE values are being well overcooked here by more than double. Storms I don't expect to be as widespread (and a little east compared to other models), though again Central Areas/CS-SW England are the most favourable locations. Next the ECMWF: CAPE values not exceeding 400J/kg, similar to various Skew-T charts I've analysed. ECMWF has a main focus on Devon, although fewer showers across Central areas. A last look at the NMM Model and EURO4: The NMM model showing the formation of several convergence zones across Central areas and the SW, although again the majority of the higher res models favoring much of the SW over Central areas. Therefore the general coverage of storms looks to be better over the SW regarding my forecast and if I had to choose a particular location tomorrow I'd have to say in and around the Yeovil area.

Was only just yesterday the Met Office were predicting UV levels to hit 6 and now they predict UV levels of 7 for Sunday and Monday. Gonna have a cracking tan by the time Bank Holiday finishes!

Have anyone taken or have seen any pictures regarding today’s storm (supercell) over parts of East Anglia today, would be interesting to see the structure of that thing as it developed into a supercell?

My post regarding the storm potential for the last few days is found here: Because of other commitments I hadn't had the time to update on the potential, until Saturday morning when I was freed of my A-Level work. To be clear, I haven't actually bashed any forecaster I continually go on about the uncertainty and the challenging nature of forecasting storms are what inspire me of these top forecasters regarding Dan, Nick and so on. The only point I ever made was regarding ConvectiveWeather's post after having updated the MDT area to cover where I live, after we had finished with all our storm activity. I regularly applaud those who put in the hard work and this is an example of me saying thanks towards CW. And finally, that chart which you originally quoted me in was away of condensing various forecasters and simplifying it for those struggling to understand what areas would receive what storms at whatever time. No hard feelings.

I understand what you're saying, but did the following storms really warrant a moderate for our area? Whilst there was still some fairly frequent lightning, wasn't anything as significant as what was earlier witnessed. If after the earlier storms passed and someone told me that there was a 45% - 60% of seeing more lightning, I'd be complete and utterly surprised as by that point the favourable conditions were much further east. Just my opinion and by good heart, but good to see another side to things.

I love ConvectiveWeather but whilst the forecast was accurate for many areas, they moved the MDT zone westwards after we had received all our lightning across Bristol, Bath into Wiltshire? Bit like the Met Office as people mentioned, issuing a yellow warning for rain when people already received all their rain and wasn’t getting anymore aha!

Here's an overview of all the lightning strikes during our thundery period over the last 36 hours. We have totaled almost 12,000 strikes! I really didn't expect too much from where I am in Bristol, but boy was I wrong can say I've used all my luck on this one; the loudest thunder I have EVER heard! As a whole CS England done extremely well, whereas North Midlands/NW England unfortunately have done poorly compared to what could have happened. It's quite interesting to note also, that it is incredible to witness such strong elevated storms this early in the season. Whilst elevated storms aren't affected by SST's, generally earlier in the season they cannot prolong their intensity. The last 36 hours couldn't have been more different, as a result of the favourable conditions above the boundary layer. Can only be a good sign for the future... right?

Interesting, so effectively the the upper level winds have prevented the storm from "suffocating itself" but displacing the updrafts and downdraft, prolonging it's intensity and growth in size?

I'm not convinced that what we have just south of Reading is an MCS. Can you explain why it is an MCS, as to me CAPE values are nothing exceptional and lack of DLS and SRH values, result in lack in organisation and structure. Not to add the area of intense precipitation isn't completely huge and lightning activity isn't anything significant. I'm open to learning, which is why I'm asking thanks!

Looking increasingly promising for those ahead of the band of heavy rain and frequent lightning across Gloucester and Wiltshire. Lightning activity should be enhanced within the next few hours through the process of nocturnal cooling, which in effect steepens lapse rates.

If things edge too Far East tonight, I might have to make my first storm chasing trip ever! Very promising

Sat24 shows extremely promising signs at the moment over NW France for tonight. Large developments within a short time frame along with new sferics!

I'm sure many are wondering why with such large values of CAPE and strong heating that many areas aren't experiencing strong thunderstorms. In my POV, high pressure is still too strongly in control. The high begins to move away from 4pm onwards which is when we should see further initiation. Unfortunately we want low pressure when we have storms, as now the high pressure is effectively pushing down on the storm updrafts preventing them from growing to a considerable height for any lightning activity. Hope this clears things up.

The showers formed North of Cardiff are a positive sign for those further NE of North Midlands etc. Further SE however, the main area of showers across South Devon are beginning to peter out. The area of cloud whilst expanding seems to be thinning across these areas at the moment.

We have lift-off, small areas of precipitation have developed over South Wales. (Difficult to tell whether radar glitch or not) Some half decent convection taking place over me here, beginning to build up in height somewhat. Sat24 shows this rapid developments in last 15 minutes.

Well here are the Euro4 for 9pm and midnight. Much of North Wales and West Midlands actually miss out, very different compared to NMM Model. According to Euro4, CS/SE England into East Midlands look a treat.

Whilst I normally have trust in Euro4, I'm rather skeptical for what it producing during the day now. At 9am, they have shown no storms to have initiated at all! And they don't even show any storms to initiate until 3pm across SW/CS England, risk looks a little eastwards compared to various other models.

To simplify some of the forecasts I've seen, I've identified the main periods of what storms to expect across the UK tomorrow. We are looking at 3 periods of storms. Ignore the key in the bottom-left I use these for my own storm forecasts.

I completely understand apologies if I was also harsh! It's difficult to explain, when the conditions are marginal a forecast will always be issued than not. Therefore times like this more times than not the forecast will be wrong, so I agree with you there. Anyhow I like that a lot of forecasts have been produced by a large variety of forecasters this time, provides me with greater confidence. And as a matter of fact to me it seems like an eternity since Nick have issued a "Yellow Thunderstorm Area" so I'm hopeful!

You aren't wrong, but I think it's a little harsh what you're saying. In each and every forecast they produce they outline the risk is very marginal and there's as much as a chance that nothing materialises. So whilst their forecasts have been so called "iffy" lately, surely their recent forecast outlines their confidence for issuing such a high risk level.

I always thought a thunderstorm of a large intensity, could effectively “use up” the atmospheric CAPE?

Unfortunately the other parameters aren't quite there for supercell development. But nevertheless with such large CAPE values (for this time of the year anyway) there will be some prolific lightning.