Bill, as a NOAA ham radio weather spotter, I can tell you a "down and dirty" radar app would be very useful.
Some thought after looking at yours:
1) Dallas/Ft. Worth wasn't on your list.
2) Here is what I use on my iPhone while in the field:
http://www.corad.org/
http://www.w5tux.com/ (a bunch of screens)
http://www.wunderground.com/cgi-bin/findweather/getForecast?query=75115

Good luck on your app!
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paul, texas KD5IVP