EGPWS
The weather radar uses the signal from the EGPWS for auto tilt.
The data base in the EGPWS contains infomation of the high ground and some radars have an auto tilt function. Armed with this information the tilt angle will be changed to elliminate ground clutter.
Not all weather radar auto tilts use the EGPWS data base, some have a data base of high ground built into the radar.