Visibility and UV are fine. Right now, for Des Moines, MSNBC does not have visibility data, and the UV index is, aparently, 0 (or else not available, either).
You can always verify that what you see with this hack is correct by viewing what MSNBC's website says. Go here:
http://www.msnbc.com/news/WEA_Front.asp?0dm=C---W Now this is important: Do NOT put in your zip code! That way gets you a different format of output that is not as easily compared to this hack. Instead, use the method under "Choose a region", it's just like picking your city from the hack.
If you do that and go to Des Moines, Iowa, you should see that (at this moment) it says -na- for visibility and 0 Minimal for UV.
As for your other questions...Yes, just upload the new weather.php (I think you already did that), and as far as I'm aware, that shouldn't fix whatever problem you're having with the forece update. I don't know what that problem is, since I'm not having it...