A sharp trough and associated substantial dry intrusion will be driving a marked frontal wave/surface low over Ireland early on Sunday morning, but this should quickly clear to the Atlantic by late morning.

The trailing cold front across England and Wales is expected to be fairly weak through most of the daytime hours as dry air overruns leaving just shallow moisture. Therefore, very little lightning activity is expected through much of the day. That said, modest heating of the residual moist low-level air (dewpoints 14-16C) combined with increasing ascent during the late afternoon and evening hours as PVA approaches from the south in advance of the next shortwave, could potentially allow a few heavy showers to develop in E Wales into the Midlands, northern England and southern Scotland - however mid-level capping due to the dry air aloft may restrict the depth of convection.

It is during the evening and night hours where the forecast evolution becomes very messy. As the next shortwave approaches from the south, to the east of the cold front a notable EML will be advected northwards from France into SE England and East Anglia, potentially becoming engaged for a time by this shortwave to generate a cluster of elevated showers/thunderstorms over the English Channel into Cen S England. Model guidance varies to how much engagement occurs, and as such coverage of elevated convection is uncertain. In either case, it seems plausible what showers/thunderstorms that do develop in the late evening to early hours period may weaken later in the night as the trough overruns and forced ascent reduces. Therefore peak intensity is anticipated around Cen S England, and a MDT is introduced as a result.

Near and to the west of the cold front (i.e. the post-frontal environment), cooling aloft and broad forced ascent in the vicinity of a jet streak will likely encourage a wide area of rain to develop with embedded convection/thunderstorms, affecting parts of SW England, Wales, Ireland and northwards up the Irish Sea to SW Scotland during the evening and night hours. Given the very complex mixture of convective and dynamic rainfall it is proving very difficult to ascertain how much lightning activity may occur - although more discrete mode would favour greater lightning potential, especially earlier in the night before the thermodynamic profile becomes modified. Some of this convection may also be surfaced-based to SSTs, and given the strongly-sheared profiles there may even be scope for rotating updrafts and the associated risk of hail and isolated tornadoes (e.g. cells moving inland into southern Ireland, for example). As such, a SVR was included for this risk.