Ok, on the Weather underground site there are two radars. One is the wundermap, which is not as good quality but has a webcam map and a bunch of stuff like that. The second is the NEXRAD radar, this is what I use. This radar has velocity and everything else. Since you said you were using the Wundermap, you may not be using what I use.
Here is a link to a map which show all the radar sites. Just click on the site near you to see it. Like I said before, the advanced options are on the left side of the screen.
Hope you like this radar better than the Wundermap.