What type of SIGMET is issued when obscured thunderstorms are forecast?

A Convective SIGMET is specifically issued to warn pilots of significant convective weather phenomena, which includes conditions such as thunderstorms. When thunderstorms are forecast, especially if they are obscured, it indicates that their effects can be more dangerous than visible storms, as pilots may not be able to see them to navigate around them. This type of SIGMET is aimed at alerting flight crews to possible hazardous weather conditions like severe turbulence, hail, or wind shear associated with these thunderstorms. Thus, this choice directly addresses the issuance of warnings for significant convective activity, accurately reflecting the nature of the threat posed by obscured thunderstorms.

The other options refer to different types of weather advisories that do not specifically target thunderstorm activity. For instance, a Standard SIGMET covers a broader scope of hazardous weather elements not limited to convective activity, while a Severe Weather Alert and a Turbulence SIGMET focus on distinct weather phenomena outside of the context of thunderstorm occurrence.