Following trends this afternoon, and model data for overnight, the SLIGHT area has been extended to the north and west of its initial area. It is expanded west to cater for ongoing thunderstorms at 15z, and northwards due to the potential for lightning associated with mid-level convection that will move into East Anglia around midnight and through the early hours of Wednesday. 

ONGOING AT BEGINNING OF THE PERIOD...  

Southeastern England

Elevated convection that will drift in by the end of Monday night will bring the risk of some lighting across Kent, Essex and perhaps into parts of Suffolk and London, before weakening into mid-morning. This is marginal for lightning frequency post 06z on Tuesday. 

DAYTIME...

Southwestern Ireland, southern England, southern Wales

Mid-level instability will be present across southern parts of England, but surface based convection will struggle to develop despite CAPE values in excess of 1000 J/kg due to a capping inversion around 800mb along with some drier mid-level air. That being said, widely distributed isolated thunderstorms are possible across parts of southern England and Wales. It should be stressed that most areas will remain dry. If a specific area can be highlighted more confidently an upgrade to slight may be made. The strongest signal for surface based thunderstorms will be across southwestern Ireland, and a slight risk has been issued for that area. 

OVERNIGHT...

Southern England

A fresh round of mid-level instability will spread out of the continent from the southeast to northwest overnight. Mid-level convection is possible quite widely from southeastern England into East Anglia and the Midlands by the end of the night. It remains uncertain how electrically active this round of mid-level instability will be. A slight risk is included for the far southeast as it arrives, but further northwest the risk remains isolated for now.