Learn about the updated 2025 derecho definition, including new criteria like hurricane-force gusts, storm length, and what qualifies a storm as a true derecho.
Learn what a squall line is, how it forms, the hazards it brings—including strong winds, heavy rain, hail, tornadoes—and why shelf clouds are a warning sign.
Learn about SKYWARN, the National Weather Service’s volunteer program that trains storm spotters to report severe weather. Discover how to join, what spotters report, and why it saves lives.