Updates to our game generally take place in two stages. The client patch and the server publish. We usually patch the clients before going to TC1 because many of the server publish changes rely on having an updated client. Without the client updates, players would not be able to properly test the update on the test center. This means that you guys as players get some of the changes for the update before the publish actually goes worldwide (in this case the snow)
When you look at the TC1 publish notes on the UOHerald, you will notice a section towards the bottom for client. These are the changes that you will receive ahead of the actual publish in the client patch.
Hopefully I didn't confuse you guys even more with this information.