What is the only cloud type forecast in TAF reports?

The correct answer indicates that cumulonimbus clouds are specifically recognized in TAF (Terminal Aerodrome Forecast) reports due to their significant operational implications for aviation. Cumulonimbus clouds are associated with severe weather phenomena, including thunderstorms, turbulence, and significant vertical development. Their presence in a TAF report allows pilots to prepare for and avoid hazardous weather conditions that could impact safety and flight operations.

TAFs primarily focus on conditions affecting airport operations, especially those that could lead to low visibility or turbulence. While nimbostratus clouds can bring widespread precipitation, they are typically associated with stable, less severe weather conditions. Scattered cumulus clouds are often benign and do not generally present serious threats to aviation. Therefore, cumulonimbus clouds are highlighted in TAF reports due to their potential for severe weather, making them a critical focus for pre-flight planning and safety considerations in aviation.