The water parks take turns closing each year from late October to late February.
Last year, Blizzard Beach was closed 10/23 to 12/24, Typhoon Lagoon was (is) closed 12/25 to 2/25. In 2004, Bizzard Beach was closed 10/24 to 12/11. 2003 was 10/26 to 12/13. So chances are it will be closed around Thanksgiving this year.