Plain English Meaning

A short weather warning sent out during flight when thunderstorms or related dangers are happening or expected. If you see one for your area, expect rough rides, possible icing, and strong wind shifts near the ground.

Full Definition

Convective SIGMETs are in-flight weather advisories issued for hazardous convective weather that affects the safety of all aircraft. They are issued for severe thunderstorms with surface winds of 50 knots or greater, hail at the surface of three-quarters of an inch in diameter or greater, tornadoes, embedded thunderstorms, , and thunderstorms producing of covering 40 percent or more of an area of at least 3,000 miles. Each implies severe or greater , , and . They are issued hourly for the eastern, central, and western and remain valid for up to two hours.