What conditions trigger a Convective SIGMET?

A Convective SIGMET is specifically issued to alert pilots about significant weather phenomena that impact aviation safety, particularly associated with convective activity. The compelling reason why severe thunderstorms and tornadoes trigger a Convective SIGMET is that these events result in hazardous flying conditions. Severe thunderstorms can produce severe turbulence, lightning, intense precipitation, and possible wind shear, all of which pose serious risks to aircraft. Furthermore, tornadoes are particularly dangerous due to their extreme winds and unpredictable nature, warranting immediate attention.

The other conditions listed, while they may pose risks to aviation, do not specifically meet the criteria for a Convective SIGMET. Heavy rain and hail, for instance, could be components of severe thunderstorms but do not independently trigger such warnings. Low visibility and dust storms relate to different meteorological phenomena and would be addressed through other advisory systems, such as SIGMETs for non-convective conditions, instead of being classified under convective activity. Widespread ice accumulation is also not a factor considered for Convective SIGMETs, as those would typically fall under winter weather advisories rather than convective phenomena.