WADR January is not warmer than February sans an unusualy warm January thaw. Here's a table fore the park:http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?wyyell
There was no thaw of consequence last year, and La Nina could very well make sure it happens again this year.
Bob, I'd post this question on forums.yellowstone.net. I saw LOTS of wolves and grizzlies on the Lamar the first week of October. As good a vehicular safari experience as I've ever had in North America or Africa since cats aren't terribly special to me like most people.
Wish I could join you but its too darn nice farther South then.