A special issuance convective SIGMET will be issued when?

A special issuance convective SIGMET is designated for significant weather phenomena that can impact flight safety, particularly from convective activity. The issuance criteria ensures that pilots are informed about severe weather conditions that could pose a risk.

The correct answer involves winds greater than or equal to 50 knots at the surface, which indicates extremely strong winds associated with convective storms, such as thunderstorms. These powerful winds can lead to hazardous conditions, including the potential for damage on the ground and severe turbulence aloft, making it critically important for pilots to be aware of.

Other factors related to significant weather, such as gusty winds, hail, or severe turbulence, can certainly affect flight operations but do not individually meet the threshold for a special issuance convective SIGMET the same way that 50-knot winds do. Severe turbulence, for instance, is taken into consideration, but the defining criteria here are specifically tied to the wind speeds that can cause severe impacts on aviation operations.