This forecast is subject to timing errors, and may be moved to Thursdays (06z onwards) forecast should it look likely for developments to occur later than current expectations.

The main period of interest is after 00z Thursday with advection of a higher WBPT airmass on the forward side of the approaching Biscay upper low. Showery outbreaks of rain are expected to move north from the English Channel into southern England during the early hours of Thursday, with some scope for embedded elevated convection. The magnitude of instability looks marginal at the moment, and so any lightning activity is not expected to be too widespread based on latest guidance.