I won't say it's completely impossible... But this is a case that will require 'extraordinary measures'. A predicted noise margin of -19 dB is going to require the best antenna you can find... or build... plus some extraordinary luck. Given the fact that you have substantial hills/mountains between you and Eau Claire you have a lot of variables and factors that the prediction algorithm can't account for. Some of those 'factors' may be in your favor, most are probably not.
Without trying, you won't know. First, can you mount high enough to clear all nearby trees and buildings?
Then, if I had one laying about, I would have no qualms about trying an Antennas Direct 91XG, DB8e or a Winegard HD9095P. However, all of these come up short of the needed gain that the cursory calculation suggests would be needed. (In theory, you need an antenna with at least 19.0 dBd (21.15 dBi) gain to just get to the theoretical edge of reception. To have any chance at reliable reception, you need some additional gain beyond that...)
So, I would be entertaining the possibility of building a large antenna. The only antennas I can think of that might produce gain like that are very big commercial products from Wade/Taco and in theory, rhombic antennas.
http://forum.tvfool.com/showthread.php?t=2865 (see post #3) A 9 wave-length per side version of this antenna, cut to operate at 476 to 482 MHz (real CH-15) will need about 40 feet by 25 feet of area and at least four supporting masts.
Another idea, using an entirely different approach... If you have a friend or family in the Eau Claire area, do you both have the internet access speed needed to stream from a SlingBox or Home Theater PC? If you have limited access speeds, you could still record the game to a HTPC hard-drive, then download it to your PC to watch at your location (at low data rates, it may take much longer to down load than the actual program length).
