What is a "SPECI" report?

A "SPECI" report refers specifically to an unscheduled observation that provides updated weather information following significant weather changes. These reports are generated when there are rapid or critical changes in weather conditions that could affect safety or operations, such as sudden shifts in visibility, wind direction or speed, precipitation, or temperature.

The significance of the SPECI report lies in its ability to relay timely and crucial weather information, ensuring that pilots and ground crews are informed about current conditions that could impact flights. Regular observations, while valuable, do not capture these immediate changes, making the SPECI unique in its focus on emergent weather phenomena. This helps maintain safety in aviation operations.

In contrast, the other options describe weather reports that either provide routine data or summarize information over a longer duration, lacking the immediacy and critical focus of a SPECI report.