Depending on how far north the frontal rain moves, it may become somewhat drier and perhaps brighter across SE England during the afternoon, within the broad quasi-warm sector. IF enough sunshine can develop (ideally lifting surface temperatures closer to 13-15C), this may trigger a few heavy showers. The presence of a mid-level shortwave, reasonably-steep mid-level lapse rates and shear aloft suggests that if this were to occur, a few sporadic lightning strikes may be possible. However, there is limited NWP support for this scenario at time of writing (primarily due to excessive cloud and subdued surface temperatures), but one to watch.

Depending on the exact shape of the frontal rain by the afternoon (there are hints it may begin to wrap around a ~700mb low), any brightness and subsequent rise in surface temperatures across SW Britain may also trigger a few isolated heavy showers, from Devon up to perhaps Somerset/Wiltshire - especially near Dartmoor. The odd isolated lightning strike cannot be ruled out here either, but given somewhat restricted convective depth the risk is considered very low (10%).

A few scattered showers are also likely over parts of Ireland, Scotland and NW England during Tuesday daytime, but the restricted depth of convection suggests the risk of lightning is also very low (10%).

Overnight, and more especially towards Wednesday morning, an occlusion will approach southern Ireland and SW England from the Atlantic. A coupled hundred J/kg CAPE in the vicinity and strong forcing aloft suggests some embedded deep convection is likely on the rear of the frontal rain, capable of producing a few sporadic lightning strikes (20%).