A Convective SIGMET (WST) is issued for which conditions?
Why →
Convective SIGMETs are issued for: severe thunderstorms (surface winds ≥50 knots, hail ≥3/4 inch, or tornadoes), embedded thunderstorms, lines of thunderstorms at least 60 miles long, or areas of thunderstorms covering ≥40% of a 3,000+ sq mi area. They are valid for 2 hours and indicate conditions hazardous to all aircraft.The trap →
Not every thunderstorm triggers a Convective SIGMET. Specific severity thresholds must be met. Isolated ordinary cells may only appear in area forecasts. A Convective SIGMET indicates the most severe convective conditions.SOURCE → FAA Aviation Weather Services / PHAK Chapter 13CHECKED APR 21ACS III.A.K1MED