TDS (tornado debris signature)

High reflectivity, a velocity couplet, and a hole in CC in the same place: the radar seeing lofted debris.

Related

CC (correlation coefficient) Whether everything in the beam looks alike. High for rain, low for a mix — hail, melting snow, or tornado debris.
Hook echo The comma-shaped notch on the back edge of a supercell where the rear-flank downdraft wraps precipitation around the mesocyclone — the classic radar look of a tornadic storm.

See it on real storms: open the radar, or read reading the radar.