BTB Terrain special rules question

I've got a question about the special rules that apply to terrain in BTB. For example in the Northern Wastes, one of the special rules that applies is "Bitter Cold". If I then look up "Bitter Cold" under the Weather Rules, then there is a further listing of special rules ("Snowstorm", "Deep Snow", "Wintery Chill", "Ice Field").

Now my question is this: do those last 4 special apply to the entire gaming table or only to specific pieces of terrain, e.g "Deep Snow" only applies to pieces of terrain with snow modelled on them? And will the "Snow Storm" be there all the time?

The rules apply to the entire gaming table (unless specifically state differently e.g. Ice field applies to lake and river terrain). So e.g. the whole area is covered in snow and the average warband will have a hard time moving through it. This is absolutely intential and means that "native" warbands such as Marauders are well advised to force unprepaired enemies to play the Avalanche scenario where those are at a huge disadvantage.

OK, thanks. Now I know what scenario I will pick next (being a beastmen player ).