Ahead of the frontal rain associated with the aforementioned occluded front, there may be a window of opportunity for some diurnal heating of the moist low-level airmass (dewpoints 10-12C), potentially yielding up to 500 J/kg CAPE. Consequently, a few scattered showers would be possible, capable of producing some sporadic lightning. Shear is a little weak and forecast profiles rather saturated, which may limit the lightning potential somewhat. This is dependent on sufficient cloud breaks in the morning hours, which is uncertain depending on how widespread / far east the frontal rain over the Midlands may be. For now have refrained from introducing a SLGT until confidence on these aspects improves.

Despite extensive cloud, weak diurnal heating will likely be sufficient for some shallow convective development near the occluded front, aided by the marked wind veer along the boundary - particularly during the afternoon hours over SE Wales / W Country / Midlands / Yorkshire. Some linear segments may develop with time, capable of producing some heavy bursts of rain - but overall convective depth will likely be too shallow for much (if any) lightning.

There may also be a few low-topped heavy showers in the post-frontal environment over northern England during Thursday afternoon.

Main risk for the remaining areas will be during Thursday night where an isolated lightning strike cannot be ruled out associated with scattered showers - though most areas will remain void of lightning.