What is indicated by the presence of TCU in METAR?

The presence of TCU in a METAR indicates Towering Cumulus Clouds. TCU are a type of cloud that typically exhibit vertical development, which can signal the beginning of more significant convective weather, such as thunderstorms. These clouds can develop in unstable atmospheric conditions and may produce localized weather phenomena, including brief heavy rain or gusty winds even if they do not mature into full thunderstorms.

Understanding the specific meaning of TCU is essential for pilots and meteorologists as it helps in assessing the potential for turbulence and changes in weather conditions that may affect flight safety. It is crucial to differentiate TCU from other types of clouds, such as cumulonimbus, which are associated with more severe weather, or cirrus, which are high, thin clouds that do not indicate significant weather activity.