I do have a strange behavior regarding the traveling path beetwin 2 regions in winter...
You may have a look at it here :
http://cedric.ligeonnet.free.fr/RUS/Divers/Pathfinding.jpg
(sorry for the file size, didn't have time to work on it - Edit : i'll convert it to JPG this afternoon)
Actually :
- with standard weather, Ivanov (or any unit) is traveling straigth from the start to his destination, using railway.
- as soon as snow falls, he's taking a detour, avoiding carfully the railway...
Edit : to be somehow more precise, what i find strange is that they are taking the way across the frozen river razer than the straigth way by railway...