The ECMWF is starting to solidify on a solution for this coming Thursday, and the low they have been promising has turned into quite an intense affair for mid May in their latest model run. Each successive run has made more of it as well as taking the track further north. At the moment the solution from the ECMWF takes the low (Marco perhaps) across central England. There are more heavy and thundery showers to come before more prolonged rain on Thursday especially in the southwest. Looking at the next ten days as a whole though, the north and northwest of Scotland should escape the worst of the rain.