How is mist (BR) defined in terms of visibility in a METAR?

Mist (BR) is defined in meteorological terms as a weather phenomenon that typically causes visibility to decrease. In the context of METAR reports, mist is specifically characterized by a visibility range that falls between 5/8 mile up to six miles. This definition is crucial for pilots, meteorologists, and other aviation professionals as it helps them understand the conditions affecting visibility, which is vital for safe operations.

When visibility is reduced to less than 5/8 mile, other weather phenomena such as fog would come into play, and thus mist is distinctly categorized to ensure clarity in communication regarding weather conditions. The range specified in the correct answer allows for a precise understanding of conditions that are less severe than fog but still noteworthy for weather observation and reporting.