That does indeed look like one of the lakes within old Coerthas. Not to mention the fact that that area was/is known as "Coerthas Central Lowlands" which with it being considered lowlands could allow it to escape being a winter wonderland. In the art books for ARR there are a few pictures of grassy areas within the Coerthas section which suggests we'll have grassy zones so I back you on the idea of Alex being within Coerthas.

I honestly believe that we'll see the four zones of Coerthas that have been excluded thus far within the expansion, look at it this way, how can you have three new jobs and only one zone within their native region? :P