Notso .... accurate
The met data is fed to both the Oceanic Centres and the major airline operators.
From that information, these airlines calculate their desired routes between major city pairs and then send the Oceanic Centres their PRMs (Preferred Route Messages). In addition, the minimum time path between New York and London (and vice versa) will also be calculated. This then gives the Oceanic Centre a good idea of where the majority of the traffic wants to fly.
The Oceanic Planner will then look at any other activity such as adverse weather (thunderstorms, etc) plus any other aerial activity such as airspace reservations and then propose a track structure. Users can then add their comments online before the final structure is then agreed with all concerned and published.
Shanwick do this for the Westbound tracks and Gander do it for the Eastbounds.
So, apart from supplying the met data at the beginning of the process, there's no planning of the tracks done by meteorologists I am afraid. I wouldn't expect them to know all the ins and outs of legal separation standards or airspace in any case
