If light snow and blowing snow are occurring simultaneously, how should this be reported?

In aviation weather reporting, when light snow and blowing snow are present at the same time, the correct reporting requires the use of a specific notation to accurately convey both phenomena. The notation "BLSN" explicitly denotes blowing snow, which is important for pilots and meteorologists to note due to its potential impact on visibility and flight safety.

When reporting, the order in which various weather phenomena are denoted matters. Since blowing snow is an accompanying condition that can affect the meaning of the primary weather event (in this case, light snow), it is essential to ensure that both are reported in a way that prioritizes clarity and accuracy.

Option A provides the correct notation "BLSN" as a standalone report when focusing tightly on the blowing snow condition. However, the combined report with the standard notation for light snow must also be captured, which can be represented effectively as “-SN BLSN.” This format emphasizes that there is light snow occurring with the significant additional condition of blowing snow.

Thus, the most appropriate reporting under the established aviation weather observation rules would actually incorporate both aspects to ensure comprehensive communication of the weather conditions encountered, thereby allowing for better situational awareness among pilots flying in those conditions.