Verification: Heavy showers at times intense developed across Ireland and S England which bought a couple of isolated lightning strikes. Lightning remained sporadic & isolated around Ireland, with only a couple of lightning strikes over North of London. A few lightning strikes were expected across NW Eng, W parts of Wales throughout Sunday Night / Monday Early hours, however no lightning was recorded from this. Overall rating: 6/10
Discussion:
During the early hours of Sunday, a front will advect from France leading to a very damp night across England. As this clears into the north sea, there is a very low chance of the odd couple of isolated lightning strikes across SE England & EA, however confidence is very low due to the highly saturated profiles.
Into the morning / early afternoon a trough will head into W parts of Ireland bringing intense showers. These showers will track East towards E Parts of Ireland throughout the afternoon and into the early evening. Cape looks to be around 200-400J/KG quite widely across Ireland with some central areas seeing 500J/KG, this amount of Cape can bring the risk of a thunderstorm or two developing, however lightning will be mainly sporadic.
Showers are also expected to develop across England which will track east towards East Anglia & South East England. Not much Cape present here, anywhere around 100-300J/kg which is still enough to produce a thunderstorm, however confidence remains low on this so we are only expecting the odd couple of lightning strikes.
As we head into the late evening period / night, the trough will continue to track E into the Irish sea which will bring intense showers to W parts of Wales & NW England throughout the night. Cape will slowly decrease throughout the night down to 100-200J/kg so only a few isolated lightning strikes can be expected.
Technical Discussion: A mass of rain from a low pressure system should clear by late morning or early afternoon in the south and mid afternoon further north leaving behind some energy forced with a wind convergence zone in England. Meanwhile in Ireland similar lines of convergence should form and help convection with rising low-level temperatures amidst slightly falling pressure. Bands of forcing behind the clearing low pressure over England should allow for some showers to be forced where energy can rise the most. This is most likely in areas where the sun can come out, just behind the strongest of the forcing bands which hug close to the low, but so does the cloud. Limiting shower depth and the strength of convective tower potential, unless clearing can become more widespread in the higher forced areas mainly in the SE and east Anglia where showers also have more moisture to feed off for that convection. Lapse-rates are strong enough for some small hail to form, but given the weak CAPE, I can't see much forming. Nor can I see much in the way of lightning because of the saturation associated with the area behind the low pressure system. In Ireland the forcing bands are more connected with the potential for convection because of less favourable conditions for thick cloud cover. Therefore stronger lift is likely to occur here and force a few showers. Stronger energy should take up more of the moisture even though it's quite weak and may lead to some heavy rainfall associated with these and they could also form into a proper line of convection by the afternoon if enough shearing were to be present. If they do, I suspect they could sustain further east than the models suggest hence why it's been extended into the Irish Sea and western Wales just in case, with a very small chance of a Supercell but shearing is lacking much strength to really push that risk. However, most likely is that these are to remain rather weak and lightning is still a fairly small risk for now. Low-level lapse-rates are strong here and so small hail is possible however unlikely to be much more than 1/4 of an inch as the MLCAPE barely reaches past 300 J/KG.