Plain English Meaning

A weather warning sent out while you're flying, telling you about hazards along your route — things like icing, turbulence, low visibility, or thunderstorms.

Full Definition

An Enroute Weather Advisory (EWA), also known as an AIRMET or SIGMET depending on severity, is an in-flight weather advisory issued to alert pilots of weather conditions that may affect the safety of aircraft operations along their route. EWAs cover phenomena such as turbulence, icing, IFR conditions, mountain obscuration, thunderstorms, and volcanic activity, and are or made through and other dissemination channels while the flight is underway.