Discussion: Ahead of an active cold front pushing into Ireland theres advected moisture from the south, tilted upwards by the low pressure system. The energy located behind the warm front that has just passed and left a fairly large warm sector with plenty moisture available into Sunday evening. Allowing for a complex of storms to build into the pool of CAPE behind the warm front, before the cold front catches up with it and shearing increases, turning what is likely a line of storms, into an MCS or potentially a squall line. Most scenarios push this from Ireland into Scotland and northern England, with a few building to the south of it, however there is a risk that it pushes right through the north of Scotland and changes the setup after it as well, as there's been a couple models that have done this. However, the most likely scenario for now does appear to be the MCS. This risks some hail and there is a chance of a few spin-ups due to the shearing. Lightning may be frequent at times and organised best if a squall line does form fully, perhaps most likely in western Scotland where newly developing cells are still possible to combine with the already formed MCS and constructively strengthen the system. The timing of this is crucial, as the slower runs appear to trail more forcing south of the system in the afternoon to increase the risk of breaking the large capping in place. The breaking of the cap appears unlikely across the Midlands across to Lincolnshire and the north during the afternoon, but if it can break, there's significant (3000+ J/KG of MUCAPE) energy available for severe potential, with the potential for 2+ inch sized hail andor an isolated tornadic risk given the shearing in place due to the cold front. The problem is that this is a less typical setup for the UK and large energy, making it difficult to forecast. The low pressure to the WNW drags up moisture, but as it passes, there's less forcing to the south of it as its more likely to eject shortwave troughs to the south of its occluded front out in the north Atlantic. However, the slower the cold front leaves, the more likely it is that as the space between the cold front and warm front shortens, the isobars appear to get dragged further south as the tilt of the longwave trough becomes increasingly negative, that may create a shortwave trough along the south coast stretching into England and increasing the forcing in the midlands and the north perhaps as far back as Wales, where the heat is more likely to break the cap. This buildup could allow for an isolated Supercell to form, unlikely to be much more, but risking frequent lightning and the previously mentioned severe risks. Given how poorly this is modelled, it's hard to say much else. The most likely area for cap break appears to be Lincolnshire, where if temperatures can reach 34°C+ as a rough guess, the cap could break. There is also the risk that the shortwave trough, could force a few storms overnight from northern France to push into somewhere along the south coast, most likely the SE given the steering. With the large amount of energy, this risks frequent lightning, but is unlikely, as anything forming is probably going to stay parallel to northern France. The shortwave trough could be slow moving enough if the cold front is, to allow a few storms to form in the Irish Sea in the evening of Monday as the cap could slightly weaken there, and they could perhaps push into Wales. But once again, the models are doing so badly at this, there's really not much idea on this.