Hail spike

They are identified by a spike of weak reflectivity echoes that extend out from a thunderstorm, and away from the radar site.

The loss of energy due to multiple reflections means weaker return echoes.

[1] Another restriction to detection is that the signal of the radar beam has to do multiple reflections, each time weakening it, and are therefore usually noticeable only in extremely large hailstone cases.

[2] In rare cases more than one hail spike has been documented with a single storm in one volume scan.

Because of their observed accuracy in indicating large hail aloft, TBSS's are used operationally by the National Weather Service to identify thunderstorms that could likely produce large, severe hail.

Example of a three body spike : the weak triangular echoes behind the red and white thunderstorm core (indicated by an arrow).
An extreme example of a three-body scatter spike caused by large debris being lofted by a large, violent tornado striking downtown Mayfield, KY on the night of December 10, 2021 .
The multiple reflections of the radar beam causing the hail spike
3-D image showing three separate TBSS signatures in one volume scan
The boxed area to the left represents the cross-section of a three body spike from an anti-cyclonic thunderstorm.