Eagle Eye

A few of my photos from this evening. I've left Twitter now so can't talk to Jay about forecasts. Will be making my own forecast maps from now on but will take a few days to setup. Discussions as usual.

Not as dire as everyone seems to think. Sure this is transitioning to an El Nino summer but its uncoupled with the atmosphere ar the moment in terms of response between surface and atmosphere. There's still some +VE AAM response but not the type that suggests wet summers. The response remains the type to a -VE AAM setup for us when thinking long term. This is a very typical response compared to the long term average. Generally, the driven relative AAM at our latitude tends to be slightly higher than the average though, towards the upper quartile. Likely a typical El Nino response. However, the distribution of that is where the actual typical vs atypical response ends up. Forecasts do suggest later into July and the coupling occurs but that could still change. Generally, we are seeing +VE AAM driving an atypical response in the Atlantic. Localised -VE AAM could drive a slightly flatter pattern of the inertial response of an atypical north Atlantic flip. Though where that flatter is, is important. The further east the flatter, the better but there's a limit. There's very little that actually needs to be changed for the trough to become the driver for a much warmer pattern which I don't like but I know others do. It also may become a thundery pattern with that trough. I think that generally this will become more favourable the further ahead in time we go. The slow nudging of the -VE AAM into the mid-Atlantic is good because it drives it slightly further away from us. The ECM might be picking up on this response (though generally too early I think). Original post: https://community.netweather.tv/topic/98519-model-output-discussion-15th-march-onwards/?do=findComment&comment=4880558

Yeah, models have tended to be over progressive over the last year or so, more than usual. So, have got to agree with you on that.

Not as dire as everyone seems to think. Sure this is transitioning to an El Nino summer but its uncoupled with the atmosphere ar the moment in terms of response between surface and atmosphere. There's still some +VE AAM response but not the type that suggests wet summers. The response remains the type to a -VE AAM setup for us when thinking long term. This is a very typical response compared to the long term average. Generally, the driven relative AAM at our latitude tends to be slightly higher than the average though, towards the upper quartile. Likely a typical El Nino response. However, the distribution of that is where the actual typical vs atypical response ends up. Forecasts do suggest later into July and the coupling occurs but that could still change. Generally, we are seeing +VE AAM driving an atypical response in the Atlantic. Localised -VE AAM could drive a slightly flatter pattern of the inertial response of an atypical north Atlantic flip. Though where that flatter is, is important. The further east the flatter, the better but there's a limit. There's very little that actually needs to be changed for the trough to become the driver for a much warmer pattern which I don't like but I know others do. It also may become a thundery pattern with that trough. I think that generally this will become more favourable the further ahead in time we go. The slow nudging of the -VE AAM into the mid-Atlantic is good because it drives it slightly further away from us. The ECM might be picking up on this response (though generally too early I think).

A few bits from this evening with more on my camera. 20230629_194928.mp4 20230629_195610.mp4 20230629_200419.mp4 20230629_205445.mp4 20230629_205740.mp4

A few photos from earlier today.

Yes, AROME has been showing sharp showers with weak to little CAPE forming into the afternoon.

Could be interesting going into next week and beyond. Wouldn't worry about positioning yet (those are two different low's with the trough forming quite quickly). The ECM shows similar but hasn't got out to the second one yet on the 00Z run.

Some pre-frontal signs of instability.

Low risk tonight but Jay hasn't been online all day for the map.

I've fully finished my non-Supercellular large hail live and pre-forecasting research and here's the link;

Finished my report on non-Supercellular large hail forecasting Non Supercellular large hail I have done 7 examples and a conclusion from my mini study. 1) 28th May 2022 5cm (about 1.97 in) hail report from developing cells south of a Supercell. You have the cell to the left of it and it’s actually the cluster in the right centre. Notice the feeder cell to the north acting as a flanking line cell for hail growth development in the main updraft. The large hail growth ‘embryo’ comes from that feeder cell which likely increases updraft strength and width because of increasing inflow strength into the storm. Strong inflow is correlated very well with updraft width. Being south of a Supercell it would’ve feeded into the Supercell, meaning that the inflow relative to the storm would’ve been through the updraft which may have limited maximum hail size. Most of the crosswise vorticity would have been close to the surface through the inflow and that would’ve artificially induced stronger rolling drag (maybe). Though the updraft width looks fairly good hence 5cm hail was reached but likely, larger could’ve been reached without the drag. There are multiple embryo stages in the storm connecting to the main updraft and those updraft embryos link up with the main updraft. Given the random processes within a storm, some mixing possibly occurred between the developing hail. This would’ve meant that forming hail could’ve been ‘passed’ through updrafts so time in updraft could’ve been increased by having multi-updraft development. Multiple updrafts can therefore contribute to larger hail as they will counteract the short growth time in a fast singular updraft due to updraft mixing. So with combining weak updrafts into the main updraft, there’s help for larger hail development. The initial modelled environment suggested that most activity would be advanced ahead of where this eventually formed. The Swiss model suggested moderate low-level-shearing (LLS) with slightly strong deep-layer-shearing (DLS). That’s not a fantastic environment for producing large hail and in fact you generally don’t get severe hail in an environment like this. That suggests that something else helped with large hail development along with the pre-mentioned multi-updrafts that formed. SBCAPE is modest at best so slower updrafts formed which meant that hail growth could’ve spent a while in the updrafts. Sometimes, you need faster updrafts and sometimes you need slower updrafts and it just depends on how much energy there is. I suspect that if there’s moderate amounts of energy and moderate updraft speed then you would want a slower updraft despite the weaker energy. Note the large boundary layer (just above it) buoyancy which would’ve counteracted for the weaker energy and contributed along with the multiple updrafts for that large hail growth. Modelling capping is always a difficulty in northern Italy especially near the coasts but with strong buoyancy, that created the lift needed to break the mixing of cap up from the Mediterranean and so models sometimes struggle in that region as to exacts in terms of breaking the cap. There appears to be a secondary vorticity lobe created which may have aided these storms on the south side of the one generated over the Alps and so, the orography likely aided forcing for storm development and strength beyond the models' best guess. Similarly, the AROME had difficulty modelling the development and breaking of the cap. With the hi-resolution CAM’s, it appears they struggle with handling of cap despite being more high-resolution. So if there’s a large cap in place, I may also suggest considering non hi-resolution models which may handle it better, likely because they have weaker cap in place because of their lower resolution. The AROME has fairly decent CAPE in place but seems to find it difficult to predict storms in its own CAPE maxima and is potentially over modelling the strength of capping advection with a warm nose up from the coast. Very interesting that this seems to be a running worry with the models in terms of their handling of cap. So, definitely keep that in mind when using CAM’s. The lower-resolution ECM meanwhile appears to have some of the best handling of the convection with the developments south of the Supercell. Like I mentioned before, that is likely due to its supposedly better handling of cap. Note that the hail growth zone here is quite close to the 700hPa layer, so is fairly low down. This would’ve put fairly good CAPE in the hail growth sector of the updraft. So, the zero line is not needed to have been worried about on this specific setup. This is one of the benefits of spring storms on large hail development compared to summer storms. The Swiss-HD model did rather well at working out cap breaking but was the only real CAM to forecast the breaking of the cap well. Cloud and capping are definitely 2 things that lots of CAM’s struggle with forecasting so I would not forecast based off reflectivity and CAPE alone. Using buoyancy to work out lift maxima areas, I tend to find is a good start. 2) 23rd June 2022 5cm hail from fairly shallow topped storm in Montenegro late afternoon. South of the main storm in Montenegro. Located slightly south of Podgorica in southwestern Montenegro. This is a theme so far, being located south of a stronger storm but producing larger hail than that storm. At a guess, it could be along a shortwave where the inflow is being forced into the updraft, more parallel to the storms advance due to the stronger storm meaning the southern mode will push more towards it than the airflow and it stays more parallel to the inflow into the updraft. That may increase the relative entrainment CAPE but keep mid-upper layer updraft speed the same. Meaning more energy but also the same amount of time in the hail growth zone. So, this is a similar outcome to the first example despite not having multiple-updrafts this time. There’s definitely some stuff to the south which may be acting as another momentum kicker for rapid increase in strength of the storm in general. The updraft width would’ve been widened because of the artificial inflow increase as well so hail growth area would’ve been widened. This time, with weaker cap and convergence or a trough, the CAM’s had a better view though mainly on the southern cell. They struggled on struggling the northern cell despite giving good energy there. There’s fairly good energy already in place so moderately fast updraft speeds but with larger energy it still would’ve made for some fairly good hail. Being on the southern side of stronger LLS but in an area of strong DLS meant that it would’ve been in that area of typical C shaped hodographs when you include the strengthened inflow as well. Potentially, the inflow layer could’ve been increased as well, another contributor to large hail. Being left of the low-level-lapse-rates (LLLR’s) maxima is typical for storm development along a buoyant airflow for larger hail than weaker buoyancy compared to the larger LLLR’s. So combining buoyancy with LLLR’s is better than the LLLR’s on their own with the better CAPE being left of the better LLLR’s which suggests better buoyancy is there as well. So forecasting purely based off either, for hail production, can lead to non development in the strongest potential hail production areas. 3) 28th June 2022 7.5 cm (about 2.95 in) hail in possible non-supercell. Looks to have been a developing Supercell, may not have been a Supercell yet. Multiple updrafts that were attempting to combine from initially semi-discrete thunderstorms providing for good hail growth mixing and total updraft width strengthening. Not all clusters like this will produce that large and damaging hail but the initial separation of updrafts meant that the combination of them worked to force some large and destructive hail to form. Hail would’ve stayed in updrafts for enough time and with enough energy to produce that significant hail. So, the clustering up of initially separate updraft embryos appears to be an efficient way of producing large hail by increasing the total theoretical updraft width significant whilst also increasing momentum and forcing into the storm. That would’ve increased EL’s and therefore the entrainment CAPE that it would’ve taken up which would’ve helped in hail production. The importance of slower updraft speeds with relatively large energy is less here given total amount of updraft and therefore faster updraft speeds will only help contribute to larger fall speeds along with larger hail. Drag will be assumed to be the same for now because it is easier to always assume that the drag is the averaged out shearing or just the LLS for the sake of this. he Swiss-HD probably had a very good handle on the forcing for clustering and the total energy as far as I can see. If you can use it, it appears to be one of the best CAM’s available for storm mode and initiation. It is interesting to see the LLS striations modelled by the model as well, showing that it handles the planetary boundary layer (PBL) very well with the exchange between viscosity and laminar flow. This is a more classical weak LLS day and I appear to have forgotten to get the DLS though I imagine that would’ve at least been about 20 knots stronger. Once again on the left of the LLLR maxima but this time better mixed in for even stronger LLLR’s. So that also suggests a fairly low down zero layer. Significant CAPE modelled suggests about 60 m/s hail fall speed if we assume 30 m/s drag which is a strong hail fall speed and also does suggest fairly big hail as did happen. When you include the buoyancy mixed with that LLLR modelled and it’s no wonder near 3 inch hail was reported from this cluster of storms though without that updraft width I imagine only about 1.5 inch hail would’ve happened. It appears to be based slightly ahead of/along a warm front. Something to note if that kind of setup happens in case it’s a frequent setup for large hail producing storms and good forcing for clusters. 4) 12th June 2021 Multiple 2cm (about 0.79 in) hail reports from late evening storm. The one near Cordoba with the inflow notch next to it which likely increased momentum. Generally, that seems to be the only real reason as to why lots of 2cm hail reports were able to occur for a time. South of a big cluster of messy storms though but none appear to be Supercellular. Located in area of weak LLS but also weak DLS. Kind of what you would expect considering it was only 2cm hail in the first place. Along with being on fairly good LLLR’s. Not much needed to analyse this specific setup. It was more just a coincidence of enough flanking cell power for low-end severe hail to occur. 5) 18th August 2022 Thunderstorm pushing into the back of a messy MCS. Likely going into the visible rear inflow jet (RIJ) slightly west of Pavullo nel Frignano. 3cm (about 1.18 in) hail. A cell forming into the RIJ will be able to take advantage of the inflow into the updraft to increase energy into the updraft which would increase potential hail size. Similarly to how we discussed before with inflow into the updraft. As long as updraft width remains stable and wide then large hail is possible when the inflow follows the buoyant zone trajectory. Given storm direction is steered by the stratiform inflow then inflow and storm direction will be relatively similar in this case. Modelling pre-storm suggested a more consolidated MCS with less of a RIJ. Modelling struggles with inflow cells because the ability to create the stratiform structure of a strong MCS is very weak with models and I think it's something that needs to be worked on because that also affects any post MCS storms afterwards. Generally, you can assume that a MCS is strong enough, if you want to, for inflow cells to form and they should be more capable of sustaining hail growth in the updraft longer than general thunderstorms so if the parameters are there then they may produce some large hail. Located in a buoyant trail behind the MCS, it is clear that the models know that they can happen but for some reason don’t form them. The LLS and DLS in residence of an MCS are often very high and theoretically that LLS weakens max hail size but enough energy should counteract that somewhat. 6) 5th June 2022 4cm (about 1.57 in) hail from cells pushing up into stratiform region of a squall line. Pretty much the same as last time actually but with a stronger stratiform region of the MCS likely due to stronger outflow winds and the inflow slightly more perpendicular to the flow which may have allowed one or two of these to eventually grow into a Supercell actually. The Swiss-HD did a rather good job of handling this and even had a Supercell further along the line on the Italy-Austria border as you can see there. This can be expected with most of the vorticity being streamwise based off the cell movement against the storm movement, the cell moves across relative to the storm movement. Cell movement is the direction of the inflow and storm movement is the direction of the vorticity. 7) 23rd June 2023 6cm (about 2.36 in) hail induced from momentum kicker cell to the north. Inflow looks to be fairly strong and a wide updraft with a cell to the left combining to help attempt to increase updraft width. Cell to the north moving perpendicular to the storm before getting ‘trapped’ increases the strength and updraft speed and size. Resulting in the growth of large hail because of strong energy and also a large hail growth zone available on the south side of the storm. Might be some fairly strong inflow to the south attempting to form some weak showers from the south which is feeding into the updraft so there’s a lot of energy and speed and messiness within the updraft. I could not find a single model which had a good handle on this. Perhaps the Swiss 4X4 did fairly well in the evolution but with it being expected to be such a messy mode it’s really hard to model well. In fact, by all accounts it doesn’t really make sense as to why that size hail formed there at all from a modelling perspective, proves how much updraft strength and momentum can help. Though there was a local LLLR maxima to use up. Conclusion In conclusion. It is very important to consider updraft width when live forecasting hail whereas updraft speed is theoretically less important than previously assumed as storms can affect their own relative energy. When considering LLLR’s, combine it with the buoyancy to get a picture of whether or not that hail environment is associated with a storm environment because if it isn’t, the LLLR’s won’t be used up anyway. Flanking cells and momentum kickers can increase updraft strength and width to introduce a hail producing localised environment even when the background signals are modest at best. It is important to note that updraft width does not have to be a singular cell but if an organised cluster of previous semi-discrete or discrete updrafts can form then the total updraft width can theoretically be used in a chaotic environment. So, if the models are showing a forced zone of buoyant air with good enough LLLR’s then, large hail is quite possible. On the south side of a Supercell where the storm is dictated by the flow of a Supercell then it may move parallel to the inflow and increase the updraft strength assuming buoyant airflow is taken from the inflow. A Supercell would take more advantage of the energy but often follows it’s own track and with splits makes it difficult to produce large hail. Generally, a Supercell will produce large hail because of the stronger entrainment CAPE and directional shearing with a stable updraft. When considering an MCS, the RIJ is a good place to look for remnant buoyant air behind or in the stratiform region with strong DLS and enough energy to allow for feeder cells to produce large hail. The stronger the MCS then theoretically, the bigger the feeder cells and the bigger their updraft width is so theoretically, the larger their hail is. From a pre-modelling perspective and the handling of stratiform regions of an MCS is often very badly done so as long as it’s a strong MCS, I would tend to assume a stratiform region with those feeder cells capable of following parallel to the inflow. Sometimes, they may not be parallel but more perpendicular and it depends on the pressure signals from an MCS and all I’m saying is good luck forecasting those from just models. Models sometimes struggle with capping problems and so look out for some very buoyant air in a capped area. That may be enough to break through capping even if it yields rather weak CAPE on the models and so that’s another modelling quirk. If available, the Swiss-HD has the best handle on the PBL which is very important in understand hail size below initial formation so using that is important if available. This is due to it’s handling of the transition between viscous and laminar flow which is very important in fluid models and convective modes with the transition of temperature between the two and lots more of important dynamical processes. The boundary layer is mostly beyond my current understanding though. The size of inflow layer will always be very important though, as will the zero line. The closer to the initial inflow layer, the better for stronger hail growth I imagine. That’s how I would use soundings for hail along with the inflow and shearing creating a C hodograph but there’s no specificied numbers for where the zero line should be and it’s dependent on the amount of CAPE it has above it as well as the inflow available to the beyond zero area. P.S. There might be some accidentally double posted images here at the end.

A few things to note; 1) A lot can hide in SRH, only use it if you're in a place without a sounding with a hodo available. Low SRH bt a large strewamwise vorticity current (so low but directional inflow) is much more likely than a large crosswise inflow layer (which has larger SRH) to produce a tornado. However, that theoretical crosswise would produce decent hail versus the large streamwise. However, that is because of the inflow layer, do not use vorticity to forecast hail. Updraft speed vs hail fall speed is a good idea to use. Updraft speed is calculated by doubling the CAPE then square rooting it. Then you can find a document online from one of the many with hail falling speed versus hail size. Do remember to factor in drag from wind and how big the inflow layer actually is. 2) To work out tornado formation versus wall cloud sitting I typically use a couple different things. The lifted condensation level (LCL), streamwiseness of vorticity and the wind flow (I'll explain later). 3cape Is useful in certain situations as well. LCL - A high LCL will mean that there is just a lot more shearing, vorticity and general energy needed to touch down. Even with very good background signals, there's very little you can do to counteract a high LCL. Streamwise vorticity - First we have to understand what it is. Vorticity is the rolling in the atmosphere created by change of wind with height. The vector of the vorticity is perpendicular to the left of the shear vector (Cameron Nixon says). The streamwiseness of vorticity. When the storm relative wind goes through the vorticity rather than across it, it 'induces' that SVC which increases tornadic potential. Look below for the through vs across. Here's what I mean with SRH not always being a good idea. Important to note that if crosswise vorticity has enough time it should be able to do what the streamwise vorticity could as well. Strong crosswise vorticity can help with anticipating a split along with the left mover and right mover bunkers. Which could help induce enough streamwiseness further along the line. That's where parcel directed by wind flow comes in handy. If the storm motion is parallel to the flow, then the storm will stay in the crosswise flow for long enough for enough strewamwiseness to build up. You only need to worry about that in crosswise vorticity situations. The more perpendicular to the flow, the less of that strewamwise can be built up. Yesterday there were fairly high LCL's and it spears that the vorticity was fairly crosswise. Though storms stayed fairly parallel to the flow, the LCL and the vorticity angle meant that storms found it hard to get beyond the wall cloud stage I suspect. If anyone wants to understand anything just ask, I've done my GCSE's and so have lots of free time now all of a sudden.

No forecast today as Jay forgot and I'm not writing a discussion for at best a low end slight risk for us. That's why we're not the professionals .

From the 8th June we've had a risk every day from convective weather. With 2 high risks 10 moderate risks 5 slight risks 1 low risk 10 severe risks.

And there we go.

Behind the cold front, the LCL's are lowered and the moisture is still there. As long as they stay close enough to the cold front they will have more shearing (shearing being parallel to the cold front) but slightly less CAPE. Could see some decent storms possibly depending on the exact CAPE.

Where are you positioned?

Those cells wrapped up in the south side inflow will be in a 3CAPE and bouyancy maxima possibly due to lofted cold airflow increasing the parcel to environmental temperature ratio. I've seen it happen before though in a case of large hail (7cm's I think but likely a better environment) so watch out for them.

Sorry if this has been shared before. Close-up look at the funnel shared.

Convective Outlook Sunday 08:00 - Sunday 23:00 (Wrote this yesterday evening with a bit added on this morning) A high end event setup with possibly a line of storms or maybe a squall line setting up with some pre-frontal cells ahead of the strongly forced line. Theoretically pre-frontal cells could be taking advantage of stronger moisture and low-level Supercell 'juice' but despite the cold fronts strength, the strongest shearing parallel to it appears rather constricted with the tightly restricted front. That restricted front appears to weaken as it hits land but may send out enough forcing for another line to form ahead of it initially with isolated storms. That secondary line looks to be tight to the cold front and so the forcing remains strong along a PV lobe sent it by the decaying front mid-afternoon. However, if it is further out then the event may be able to form a Supercell, it's a matter of miles. If a Supercell does form then low-end large hail is possible along with a tornado. Generally a brief-spin up and 2cm hail is more likely if its a line of storms that forms. If a line does form then just below severe wind gusts may occur. Interestingly, having studied a precious event, if there are individual inflow cells into a squall then they may be able to form large hail themselves. I suspect the low-level bouyancy is artificially increased slightly south of a squall line so larger 3CAPE which can yield larger hail. In fact the Swiss 4X4 is currently modelling something similar south of the line with cells forming south of the line between Birmingham and Sheffield with slightly increased 3CAPE and the GFS suggesting locally increased lift. This may allow for active storms and hail producers south of the line but it depends how forced the line is. Ahead of that second line that forms and a convergence line could form on the coast and right on the NE coast, strong storms could form drifting off into the North Sea given large CAPE and bouyancy which could very much be strong and active as they push into the north sea. With less forcing they become less messy and a possible Supercell could form making the most of that entrainment CAPE. A local SRH max with these storms is being modelled with a strong inflow layer and mostly streamwise vorticity in places. This may allow for both low-end severe hail and a tornado to form. The specific temps and dewpoint at layers is looking possibly Supercellular as well. So an area to watch out for is ahead of the line towards the coasts. Some models do show environments capable of hail slightly above 1.5 inches in areas but without a Supercell there that won't be realised. So it'll be very important for a Supercell to form if the severe potential is to be realised. LCL's are rather high which may limit ECAPE and the tornadic risk but its not majorly high and is just another complication to the forecast. For now I've just decided to pretend it's a bit lower because it could well be. Environmental modification more favourable could still take place given we've still got plenty of time till the event. Models could be underdoing the total CAPE or may be overplaying the shearing slightly and that's just one of the niches of forecasting that you've got to try and factor in. So some severe hail, an isolated tornado and near severe wind gusts are possible. This along with frequent lightning and a weak Supercell maybe. Some surface flooding could also occur given the multiple rounds possible in some areas.

And that's why people should wait and do their own forecasts. Rather than hyping something up based off 1 model run 3 days out. Anyway, tomorrow is only as disappointing as you make it. Enjoy everything to a big extent and you'll find much more joy in small storms, that's why I'm out here saying storm of the year after I get a moderately good shelf cloud and 2 lightning strikes.

Here's my European severe weather risk for tonight and tomorrow. Though most models don't show it, a couple models still are showing an intensification of a storm within my slight severe risk area in terms of wind gusts and hail risk so had to include that as well as the already existing tornado risk.

Convective Outlook️ Saturday 13:00 - Sunday 07:00 Embedded Thunderstorms possibly Severe are expected to across W parts of Ireland which will then also develop towards W Scotland. Occasionally frequent lightning can be expected alongside heavy rainfall totals, gusty winds, hail and possibly an isolated funnel/tornado. Fairly strong lift and moderate shearing could allow for these active storms to form. This along an active cold front with lots of available moisture. Shearing parallel to the cold front looks to be very strong, mainly behind it thoufh but the LLS along the active cold front and slightly ahead of it could still well be 40 knots in areas. This upscaling as it hits the coasts should happen overnight. Strong forcing with fairly high vorticity into developing clusters and possibly a squall could allow for a brief spin-up. Most likely crosswise vorticity but may become a streamwise current within southern areas with a different inflow layer depth and inflow area. Fairly strong outflow winds with lots of heavy rain could easily form a RIJ. This is where the local cold pool increases and backwards convection is strong than modelled so therefore could be larger than modelled. It also means the straitform region of the MCS is larger (potentially slowing it down?). Northwards gowards the Scottish coast and there's a secondary cluster possible on some models. Larger SRH may indicate that has a better chance of a weak spin-up but it generally stays over seas. The 3CAPE in the main MCS appears to be plentiful with 150+ J/KG for some strong storms with embedded hail. Though generally likely to be non-severe. Saturation is fairly high and that may decrease some of the lightning activity. Though we'll just have to see.

Here's some of what I got that evening. Excuse the zooming in. I'll be honest, can't be bothered to scroll through to the originals on here so just got them off my social media cropped photos.