The greatest threats to an aircraft operating in the vicinity of thunderstorms are?

When considering the threats to an aircraft operating near thunderstorms, turbulence and hail present some of the most significant dangers. Thunderstorms are known for their tumultuous conditions, which include severe turbulence often caused by updrafts and downdrafts within the storm. This turbulence can pose serious risks to an aircraft, potentially leading to loss of control or structural damage.

Hail is another critical threat. Thunderstorms can produce hailstones that can severely damage an aircraft's exterior, particularly the windshield, wings, and other critical components. The size of hail can range significantly, and even small hail can be damaging at high speeds.

While heavy wind and rain, low visibility and lightning, as well as freezing rain and ice can indeed create hazardous conditions, the immediate and potentially catastrophic effects of turbulence and hail make them particularly formidable threats when operating in the vicinity of thunderstorms. This emphasizes why turbulence and hail are considered the greatest threats in such scenarios.