What type of weather advisory would indicate severe turbulence potentially affecting flight safety?

The correct answer is SIGMET, as this type of advisory is specifically designed to provide information about in-flight weather phenomena that might pose a threat to the safety of aircraft operations. SIGMETs are issued for hazardous weather conditions such as severe turbulence, extreme wind shear, thunderstorms, and other significant weather events that could impact aircraft safety.

While AIRMETs also provide important weather information, they generally cover less severe conditions that might still affect smaller aircraft but are not classified as hazardous for larger commercial operations. METAR reports are routine aviation weather reports that offer current conditions at airports, while TAFs are forecasts for specified times, focusing on expected weather over a 24- or 30-hour period at an airport. Neither METARs nor TAFs are used to specifically indicate severe weather hazards impacting flight safety in the way that SIGMETs are.