Eagle Eye

Southern Storm Thank you, just a case of waiting to see what happens now. Forget the models and hope for the best, blue skies here though and some accas on the sky are good signs.

Jamie M Agreed, we are once again looking at France and hoping they don't sort of take any potential energy for our storms as they often do, hence why I only wanted a slight risk. There just too much going against it at the moment.

I'm not convinced of the moderate and wanted to go with the slight with AOI risk that we made but Jay went with the moderate so here's today's risk. Convective Outlook️ 50+ J/KG of 3CAPE could form over the SE during the evening hours along an envelope of deeper moisture pushed by a forcing lobe north of the original one over France. This could help push a few thunderstorms to form mainly in the SE but perhaps in areas further north along the east and areas a bit further west along the south coast. Also, an area of storms could form mostly in the Irish Sea but hit the Welsh and southeastern Irish coasts. The further south this forced band in the SE or eastern part of the UK is, the worse it is, as the France storms expand north, those storms could become part of some sort of MCS or cluster of cells and weaken as they could become constructive momentum feeders for the French cells. Also, it's not guarantee that the forcing will be enough to get meaningful CAPE together and instead, we'll be relying on initiation further west over northern France pushing into the SE, which is looking like the most likely scenario on the models and it's half and half as to whether the SE and eastern parts get anything. Perhaps they could survive the channel because they are likely to be the only storms or the day and so the CAPE hasn't been taken up, or they could force new cells to form ahead or along with them on the south coast into a cluster that the shearing favours. There's a small chance of a tornado within this given the low-level shearing but the energy is likely too lackluster to really help. That also likely means hail would be kept to quite small. No matter where there storms form, 500+ J/KG of MUCAPE appears likely and it could reach up to even just a bit more than 1000 J/KG of MUCAPE mostly held beyond a surface inversion, which if that holds, could help stop surface storms from forming in France and go immideately to elevated storms, likely to be less severe, but bring a higher risk of lightning for eastern parts of the country, mainly the SE. DCAPE could be enough for some meaningful but less than severe wind gusts with these. However, the energy is what looks to keep it sub severe, it doesn't seem to reach the 500?+ J/KG of DCAPE for downdraft to be meaningful enough for severe wind gusts from the potential storms. Lightning could be fairly frequent from these especially as they appear to miss the highest of the saturation that is held in the lower levels. However, there appears to be still some fairly strong mid-level saturation for the storm to work through along with a lot of moisture to slightly dampen lightning risk and increasing the small flash flooding risk. The WRF is especially strong with all this, giving some areas 1000+ J/KG of MUCAPE with a hooked low-level where just enough low-lebel energy is present, beating the surface inversion but over the SE, for a small tornadic risk. If surface based energy can properly be forced as the WRF suggests over the SE then we could well see very frequent lightning and storms with severe capabilities but only realltr the WRF is that severe with this energy its showing. However, it's got many previous events of similar nature right whilst other models have struggled, so it's something to keep an eye on. Buoyancy shouldn't bet too much of an issue, it's kind of just there, however that's for the models where the forcing band is evident. If it isn't then the lift in the atmosphere probably won't be enough anyway and there'd be too much opposing the storms. Hence why it's such a difficult forecast for eastern parts of the country shown by all the model differences that are still very much evident. Just enough energy of about 300+ J/KG of MUCAPE over the SE Irish and Welsh coastal risk could allow for a band of storms to form into a cluster quickly into the late evening, perhaps staying in the Irish Sea but could hit coasts as rit moves north. There's good model agreement that these should form though. Here's the risk that I wanted to go with. But we'll see, I was more worried about the fact that it's very 50/50 on the models so I don't think a moderate would be an accurate representation of the risk.

Lots of differences for tomorrow mgohts potent potential storm risk with some severe hints. Most models have it sliding desperately just out of reach from us, but the UKV has more developments for the eastern parts and quite a strong system forming. Likely a case of we'll see what happens and model trends. This is occuring on a lobe of forcing within a deeper moisture band ejected from northern France area, leading to development of what appears to be a shortwave trough for those potential showers or storms within it. That band is forced up because of the low to the SW, the positioning of that being very important. 3CAPE is just about warranting of severe potential, but I suspect the UKV would be more of an advection of that surface energy. This is given there's a deeper pool over northern France that's around 200 J/KG of 3CAPE according to the Swiss models. Hearing is very much sort of there, especially over the mainland parts. That may warrant some kind of severe threat, I'll wait till tomorrow to properly go into it. Whilst not major, the low-levels are especially sheared. Fairly decent CAPE on the UKV shown, but likely not enough for all the showers forced to have lightning within them, only mainly the ones in the SE. The UKV can tend to underdo the energy though and especially has recently with the early season risks its been quite low compared to some of the other models. Saturation looks high though. That'll likely keep the lightning down to a minimum unless it trends down. Lots of potential moisture for flash flooding on the other hand. Buoyancy is still largely varied on the models. Forcing could well turn out to be anything if these are anything to go by.

viking_smb Most likely but I wouldn't rule out the odd strike or two still.

Cain Saturation too high unfortunately, so only sporadic lightning, hence why it was a low risk.

CoventryWeather Probably moving too NNE rather than NE to be that interesting for where you are unfortunately.

CoventryWeather Expect it mostly to be a mess as it's down trended but could well still see some sporadic lightning but good luck capturing anything.

Convective Outlook️ 150+ J/KG of 3CAPE should form on Saturday evening leading or storms developing over the SW and south Wales moving NNE throughout the evening and night. This forms along a lobe of forcing that stays relatively still as the storms move up the band of forcing, helping to sustain it. Some showers may also form in Ireland, dependant on how much forcing can actually form there. There may also be some lightning in the front in the SE, but it looks primed to get stronger over the north sea rather than the SE. Very high deep-layer shearing at 80knots just southeast of initiation which appears to be mostly speed shear rather than directional based shearing which should help with upscaling into a multi-cellular system or clusters. However, weak CAPE should keep lightning down to sporadic especially given weak depth of CAPE. Lifting is fairly strong on most models but doesn't look strong enough to significantly help with developments into proper convection centres and that may mean thst less tower based convection could occur and it becomes a dying cluster of cells very quickly. A lot is going against these being long-tracked cells with frequent lightning, it's looking like sporadic lightning pretty much all the way through at best. This is on the far western edge of a significsnt Theta-E ejection centred over eastern parts of the north sea but there does appear to be some forcing for a secondary band of moisture along the forcing lobe, potentially leading to risk of flooding given the moisture potential and the risk of clusters of heavy rainfall falling for flooding risks, especially in higher saturated areas, although those have lower lightning risks. Saturation is an issue but the edges of the system and new developments look to initially develop in areas without saturation as it moves, so not fully an issue. Though, quickly those should be brought into the system as it continues onwards, if it does become a full system. Showers may trail to its south with less saturation, risking further strikes down even on the south coast, though the energy is still lacking in depth there, so sporadic lightning is still likely at best. The Ireland risk has quite a lot of energy but seemingly very little trigger, risks some fairly frequent lightning is something can get going but very few models have much. Saturation is quite a lot with this though. The SE risk is very low but the Theta-E is more evident there and in the north sea, along with some forcing to help towers to form, but mainly past the SE. In the main system the tornadic potential is there but low as the low-level shear is strong and could combine with the low-level forcing and energy. Along with some flooding risk given lots of rain across the UK recently, and the risk for heavy rain with this system. Saturation is a huge issue with the lightning risk hence why we've kept it as a low risk. There's also a wide area as to where the storms could be so we've gone for a wide severe.

Sprites Thank you but I don't think so,I gave it too much in terms of how it would avoid the saturation. The saturation very much meant that it was sporadic strikes all the way through as it always does, unless it's below about 70%. I need to start downgrading risks when the saturation trends up.

ChannelThunder The storm that formed meant not much, if anything else could form because it took up all the energy and a lot of space.

Thinking about it, I haven't had a daytime storm since come close to this and this is nearing 4 years ago now and I'm slightly annoyed because imagine this but I actually had my camera and I was doing a proper setup. No lightning has been that close to me since that day, well not something I've got on camera anyway and I haven't heard thunder really like that, mostly it's been rolling whereas this comes in quickly then rolls, most big thunder for me has been rising and I'm hoping this will be the year where a strike is just beyond those trees again ( don't think it hit them, probably just a camera quirk) and I capture it on my proper camera that footage I take is taken with now. Would also get the thunder in even better. 11995277_VID_20200828_1449024.mp4.be998ddea9a8352dbd9ca4f3d666e17f.mp4

Heading right towards the moderate risk and seems to just about be keeping energy by recycling. Also might be a squall line forming with the rain behind becoming stratiform rain, if so then watch as to how that behaves. The weaker that is, the loss cooling occurs, and the more the frontal cells can keep going. Does pretty much rule out anything else if that is happening. However, it manages to keep going because of this, also means that forcing is slightly better than most forecasts happened to have the forcing as.

viking_smb Convective Outlook️ A complex of showers and storms should form Wednesday night across the southern coasts, perhaps evolving into a squall line if forcing can allow it. Lightning may be quite limited unless forcing dramatically increases on the models for constructive mergers to occur for MCS growth. That is looking unlikely at the moment, with mainly downgrades. Saturation is high and that limits lightning without the high forcing, might lead into heavy rain rather than storms if no breaks in the extremely high saturation forecasted on some models. Lightning still is a risk mostly though and could be frequent in the case mentioned earlier. High 3CAPE does favour lots of low-level energy for hail and tornadic activity. Hail may be near severe if the low-level shear is negotiated with low storm bases, and that would also help with mainly coastal tornadic risk. Strong wind gusts are moving through at the same time and may be of severe status, perhaps influenced to even stronger given the low-level energy and windfield around the boundary layer. A squall line if it does form could also increase that risk. The timing is throughout the very early morning for the southwest and extending east later on towards 3 to 5am roughly and lasting through till mid morning in the SW and towards 8 to 9am maybe in the SE. A few showery storms could linger in eastern parts longer on the Northern part of the initial weakening showers. Thunderspotter CAPE is the convective available potential energy but I think that's surface based CAPE and as its night, theres rarely much surface based CAPE. Should be more when you go further up. Gone moderate because there's already storms closing in which is potentially a good sign.

ChannelThunder Yeah problem is that it's beginning to look very messy now as deep-layer shear increases on the models. That's leading to a lot less storms on the models, especially further east. But, we'll see what happens tonight. However, look at the UKV.

WeatherArc Lots of cars on the street with a high-end potential tornado closing in on them

This could well be 'the' storm. @WeatherArc good timing ha ha.

It has that look. Paramaters aren't quite there but my goodness me does it have that look.

Mini-forecast for Wednesday night using both main Swiss models and the AROME and WRF. On the western edge of an advected theta-E envelope, Wednesday night has the potential for some thunderstorms along the south coast. Strongest Theta-E of the year it appears is very possible. 3CAPE looks to be very strong for night, mostly surface based developments, but perhaps a mix between the two. France surface based storms won't be an issue, and nor does the channel seem to be, as they initiate over the channel with that surface energy. Perhaps pulsing forwards with different bands of showers andor storms rather than specific ones till they hit the coast. This allows for cells to form through the channel and along the coast for the south coast. Mainly in the southwest but does look to extend eastwards throughout the night. They may be parallel to the coast, with the Theta-E envelope or perpendicular to it, but I suspect that developing parallel would allow for better use of moisture. Alternatively, could mean that it stays in higher saturation and lightning is more limited as the moisture-temperature gradient is potentially lower. Buoyancy is still varied with different models. You can especially see the limit of the almost dryline to the north with developments to the south of that. The lifting isn't really an issue here. Saturation is quite high and the column profiling here based off these models looks quite poor away from the southwest and that may significantly limit lightning. Then the other model pushes the drier air over Wales further southeast and that's the better scenario for lightning potential, also may allow a clearing more of the rain thats likely to push earlier. Deep-layer shear is stronger over the SE and central south, with very little over the southwest. Supercellular potential seems unlikely to be honest. Even away from the southwest. Shearing at the low-levels is a completely different story though, the coastal difference and friction may allow for some spin-ups to form depending on the 3CAPE and vorticity as well. Hence the potential for rotation is there. Clearly it's not that significant based off how much could potentially go towards rotation though. Likely not much hooking in the low-level wind profiles then. Some tornadic potential there. Lapse-rates in the SW are also on for hail potential. Though the shearing profiling can be very lowering of that potential for hail. Given previous events this year, that seems to be less of a contentious issue than I would've thought. AROME is more of a different approach with it moving more directly west to east. Still a fairly decent event for early storm season on the AROME though and maybe good signs that we're getting towards proper plume potential where it can make it across the channel with enough energy backing it. Profiles are quite highly saturated, but the mid-levels may lose some saturation and in the hail growth zone as well. That'll lead to better conditions for hail growth and also the downdraft to be stronger, maybe leading to surface wind gusts, but also, the hail more directly forced downwards, once growth occurs, especially best if the downdraft and updraft seperate strongly. Hail may get to near severe or severe status based off that.

Convective Outlook (Wednesday) ️ Showers will develop across NE/E Eng down to majority parts of EA, which may become thundery particularly Hull down to Norwich where an Area Of Interest has been added. Saturated profiles will limit lightning activity, however a few strikes may be seen.

Saturation is high at the moment and may help limit the threats. But could well become less saturated by the time of initiation. Still a very high-end potential event, no real changes since yesterday, except the area slightly moving west and south a bit.

00Z HRRR keeps making it worse for tomorrow.1 day out from that anniversary as well. Tornado threat continues and potentially upgrades but its moved west slightly and the timeframe may be shorter.

Robert1981 not mine but agreed there.

Wow