What must occur for a "SPECI" report to be issued?

A "SPECI" report is issued in response to significant changes in weather conditions that are relevant for aviation safety. This type of report is more specialized than a regular METAR, which provides standard weather observations. The issuance of a SPECI indicates that there has been a noteworthy alteration in any of the critical weather data, such as visibility, wind speed or direction, the presence of significant weather phenomena, or temperature.

Such changes may affect flight operations, so timely updates through a SPECI ensure that pilots and other aviation personnel have the latest and most accurate information to make informed decisions. Essentially, the SPECI report serves to highlight instances when significant modifications occur, thereby fulfilling the need for enhanced situational awareness in aviation contexts.

The other options do not align with the criteria for when a SPECI report is issued, emphasizing the importance of the requirement that critical data must change to necessitate this specific reporting.