Yes we have this in the Avro RJ100.
The weather radar display is in the central area between the pilots. This can show terrain or weather as selected.
We also have a weather radar on our own, independent range scales overlaid on each Navigation Display (lower EFIS screen). This one can show only weather, not terrain.
So to get what you're saying, you can set the weather radar "terrain" mode on - it will then show the terrain (as cough says, it's not radar, just a display of where we are in relation to its terrain database) - that's on the centre screen, with the radar layered as bright or dim as we like along with the localiser or whatever on our NDs.
If you don't have EGPWS, you can angle the radar down so terrain fringes appear in about the top 10% of the screen and the rest of the screen will then show a combination of peaks and weather. It takes a lot of practice to interpret, but plenty of people have been doing this for many years.
I liek to use this kit every chance I get in the mountains even in fair weather to get the hang of how to use it.