The tvfool radar report and channel list shows that the Tucson Digital Tv channels are receivable at your location.
Aim the antenna at about 120 degree magnetic compass direction and do a double rescan to clear out the tuner for a fresh scan you the Tucson channels.
http://www.dtv.gov/rescan.html.
Here is how to aim antennas ,
http://www.kyes.com/antenna/pointing/pointing.html.