Is the incoming flight to Dublin (seems like it's AC804) cancelled? Assuming the plane is there, AC isn't going to want to leave an airframe in Dublin just sitting there very long and not being productive, so even if there was a delay I think they would still be there to fly you to Canada once conditions allowed...having said that, I think it looks pretty easy to divert around that storm on that route at that time and I wouldn't expect any major issues from that, per se.