Radar & severe weather guides
Learn what the colors mean, how to spot rotation, and what to do when warnings are issued.
How to read weather radar
What radar colors and dBZ mean, how to judge rain, hail and storm motion, the storm shapes that matter, and the limits every radar has.
Tornado watch vs. tornado warning
A tornado watch means conditions are favorable; a warning means a tornado is happening or imminent — take shelter. Who issues each, how long they last, and PDS and tornado emergencies.
How to read velocity radar and storm-relative velocity
What red and green mean on Doppler velocity, how to find a rotation couplet, why storm-relative velocity (SRV) works better, and pitfalls like aliasing and range folding.
Correlation coefficient and tornado debris signatures
How dual-pol correlation coefficient (CC) works, why it drops in hail, melting snow and tornado debris, and how to recognize a tornado debris signature (TDS).
What is a hook echo?
A hook echo is a hook-shaped appendage on a supercell's radar image that wraps around its rotation. Where to find it, why it forms, and why not every hook makes a tornado.
Tornado Alley and Dixie Alley
Which states are in Tornado Alley and Dixie Alley, when tornado season peaks in each, how the two differ, and how tornado activity has been shifting east.