I tried some of those HUD apps. Most glass is double-pained or something so everything reflected you see in double.
You don't need a dedicated weather radar app.
You can go to NOAA.org and save the radar pages as Apps on your main pages. That's what I do. Loads up straight-from-the-source Wx radar on demand. Good stuff.
This is but one of the MANY products NOAA puts out.
http://www.wrh.noaa.gov/zoa/mwmap3.php?map=usa