It looks to me that the GFS and ECMWF models start to diverge from around next Friday (T+120) when the GFS has cold air to the north repulse a low and another advance of mild air much more effectively than the ECMWF model does. The GFS solution then goes on to develop a low across Iberia (T+144) which gradually moves northeast into France (T+192) to enhance the easterly flow across IONA. The ECMWF solution fails to do this maintaining a low to spiral around the north of Scotland allowing pressure to build across Iberia and tighten the southwesterly flow to the west of Biscay. In ten days time their solutions are complete opposites, with the GFS anticyclonic cold anticyclonic easterly and the ECMWF’s broad mild southwesterly. It will be fascinating to see whose solution is correct.