Radar-Indicated vs. Observed Tornado Warning

What radar can see

Doppler radar measures motion toward and away from the radar. Strong adjacent inbound and outbound velocities can reveal tight rotation, but the beam may sample the storm above ground, especially far from the radar. A warning can therefore be issued before anyone confirms a touchdown.

Dual-polarization radar can sometimes identify lofted debris. A tornado debris signature provides strong evidence that damaging circulation is on the ground.

What observed means

Observed wording reflects credible confirmation; it does not promise that every point in the polygon will be hit. Tornadoes can change strength, lift, redevelop, or become hidden by rain.

Reports also take time to reach forecasters. A radar-indicated tornado may already be producing damage before its tag changes.

The action does not change

Inside the polygon, move to shelter immediately for both tags. Use the wording to understand confidence, not to decide whether a warning deserves action.

Follow later warning statements because the polygon, storm motion, and confirmation can change quickly.

Frequently asked questions

Is radar indicated a false alarm?

No. It describes the detection method. Forecasters issue the warning because the circulation presents an immediate tornado threat.

What is a debris signature?

It is an area where dual-polarization radar detects objects with varied shapes and orientations collocated with strong rotation, consistent with debris lofted by a tornado.

Can a spotter report be wrong?

Reports are evaluated, but visibility and communication are imperfect. Official warnings combine available radar and ground evidence.