I find it quite remarkable that the powers that be would order flights to be cancelled so far in advance over something so unpredictable... all of the weather models struggle when it comes to convection and trying to pin down exactly where storms will be even 12 hours out is nigh on impossible.
Last night proved that well - I was awoken around 3 AM by frequent thunder and lightning. I groggily went to the PC, looked at the radar and there was a mass of storms moving up from France over my part of Kent. The Met Office forecast at the time was for partially cloudy skies... it was only once the storms started easing that the model updated to show thundery showers for the next three hours!
NB, for those watching the Netweather radar you'll see the rainfall has crossed halfway over the Channel now. The intense storms are remaining near France, however, they're moving only very slowly northwards. For those without access to Netweather or a similar 5-minute product, this link should give an idea of what's going on:
http://www.meteox.com/gmapstatic.asp...om&x=246&y=277
Edit: free satellite link for EUMETSAT:
http://www.sat24.com/en/gb