Nebada with each a pronounced as in father would be the proper Spanish pronunciation. However, modern usage is Navada with the first and last a pronounced as in father and the middle a as in bad. Also drag out the middle a so Navaaada to get the proper trailer trash intonation.
I dunno - I pronounce it Nevada, like Nebada (ne-Bah-dah, or like the sound of the O sound in bother). Slight emphasis on the va part. I think the way some people learn word pronunciation (partly to fault of any accent), the way we roll the pronunciation of the eva part, the e get morphed a little to sound like whatever is following the V as well. Because I've heard a lot of the expected E part, with proper sound, at least around NW Ohio - the default "accent" of the US, the accent of the national media.
Though we do have an old street named Nevada, though locals pronounce it Ne-vay-dah. We might have the Polish history of the town to thank for that though.