What type of weather does a report of TCU suggest?

The report of TCU, which stands for Towering Cumulus, indicates potential thunderstorm activity. TCU clouds are usually an early sign of developing convective activity in the atmosphere. These clouds, while not yet at the level of fully developed cumulonimbus clouds associated with thunderstorms, can suggest that the atmospheric conditions are favorable for further development into thunderstorms.

Towering Cumulus clouds are characterized by their vertical growth, and they may produce some precipitation and transient showers, which are indicative of instability in the atmosphere. The presence of TCU can alert pilots and meteorologists to be vigilant for possible thunderstorm development, even if thunderstorms are not currently present.

In contrast to the other options, such as overcast skies, clear and sunny weather, or heavy cloud cover, TCU's specific association with atmospheric instability makes it a direct indicator of the potential for thunderstorms. This is distinct from other types of clouds that generally do not imply the same level of intensity or weather activity.