Which of the following areas is NOT a concern when flying near thunderstorms?

When flying near thunderstorms, fog is not typically a primary concern compared to the other listed phenomena. Thunderstorms are associated with various hazardous conditions, such as turbulence, heavy rain showers, and gust fronts.

Turbulence is a significant issue, as thunderstorms can create severe updrafts and downdrafts, leading to abrupt changes in altitude and attitude. Heavy rain showers can reduce visibility sharply and affect instruments, making navigation and safe flying difficult. Gust fronts, which occur when cool air from a thunderstorm downdraft spreads out and hits the ground, can create strong winds and additional hazards for aircraft, particularly during takeoff and landing.

While fog can indeed present challenges in aviation, it is usually not directly linked to thunderstorms. Instead, fog often forms under different meteorological conditions and is typically associated with calm conditions that do not include the severe weather patterns of thunderstorms.