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Posts posted by Eagle Eye
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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.
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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.
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The storm that formed meant not much, if anything else could form because it took up all the energy and a lot of space.
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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.
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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.
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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.
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.
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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.
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Lots of cars on the street with a high-end potential tornado closing in on them
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This could well be 'the' storm. @WeatherArc good timing ha ha.
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It has that look. Paramaters aren't quite there but my goodness me does it have that look.
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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.
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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.
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Robert1981 not mine but agreed there.
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Wow
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18Z HRRR
Ohio very much at the epicentre of significant tornado probabilities with Supercells evolving linearly and the probably eventually becoming a squall once the forcing pushes it into one. However the early part of this event could be very significant tornadic potential wise. High SRH where the vorticity is mostly streamwise and lots of low-level energy. Fairly strong energy being converted into potential for rotation.
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I think tomorrow is a lot more potent with potential than today, looks very significant at the moment. Properly strong start to the main 2 months of storm season in terms of potential, even though it's not really a typical area.
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Hail moderate risk and maybe the chance of a strong tornado. Not the best chase conditions today but it's certainly quite a big event anyway.
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Very much bust category here. Perhaps more saturated than expected and too much coverage of weaker showers didn't allow bigger ones to build.
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Lightning just north of you apparently
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3 to 4 pm looks to be where the showers are going to get more widespread and also push further north. I suspect that's when the main lightning potential is as well.
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Struggling to light up at the moment but the showers are there.
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Storms and Convective discussion - April 2024
in Storms & Severe Weather
Posted
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.