A nice overview of radar coverage across the United States is presented in a published paper in Weather and Forecasting by the late Bob Maddox et al. in 2002.  It is linked here.  H/T to Cliff Mass for sharing this article with me.  I'm not a radar meteorologist, but the complexity of the topography in the west sure plays havoc with radar interrogation of storms, as evidenced by their figure 3 (copied below; © American Meteorological Society).  Placement of the radars will matter!