Found this map on the southeastern palm society website. It is for a 30 year period and more or less mirrors the arbor day map. It will probably be very similar to the new USDA map (should it ever come out). Keep in mind that it does not even include the last 11 years (warmest decade on record). One can infer the second 15 year period from the 30 year average. If Knoxville is 3.5 for 30 years and was ~0 for the last USDA map (6b/7a), then the average for the second 15 years is around 7. I am planning on doing a new map with 2000-2011 added, which should add another 1/4 of a zone.

http://www.sepalms.org/Climate/TN%20Zone%20Map.pdf