What does a hook echo indicate?

• A. A storm type with minimal precipitation.
• B. A reflectivity pattern that can indicate a tornadic supercell.
• C. A pattern indicating clear weather.
• D. A feature used to identify hail size.

Answer: (B)

A hook echo shows a hook-shaped reflectivity pattern on radar that forms when precipitation wraps around a rotating updraft in a supercell, creating a curved line of heavy echoes at the storm’s inflow region. This wrapping indicates a mesocyclone and low-level rotation, which are the key ingredients for tornado development. The hook is a visual cue that the storm has organized rotation in its core, often accompanied by rotation signatures in velocity data, signaling tornadic potential. While not every hook echo produces a tornado, it strongly suggests a tornadic supercell and warrants urgent attention. It’s different from patterns indicating clear weather, minimal precipitation, or hail sizing, since the hook specifically points to a rotating, tornadic-compatible structure.