>From what I gather, imagery is no longer being generated at the Western Region level, but is coming from NESDIS. Hopefully, the county lines will come back again soon.
In my humble opinion, it is hardly Tucson centered. Not even if you consider the entire CWA. There needs to be much more coverage to the south and to the east, outside of cool-season systems, for which the Phoenix-centered image compensates, there is no coverage south of 31N nor as far as 108W. It "seems" to be centered just east of the jct of I-8/I-10 which is, in fact outside the Tucson CWA.
For what it's worth, you can get a more "customizable" version (lat/long, highway, etc) of the same image at the URL: http://www.ssd.noaa.gov/goes/west/wfo/twc.html
I do miss the old links.. I like this : http://weather.msfc.nasa.gov/GOES/