Plain English Meaning

It's a short code in a weather report that adds extra detail to a weather event, telling you what kind it is or how it's behaving — for example, whether rain is showering, freezing, or coming with a thunderstorm.

Full Definition

In a METAR, a descriptor is a two-letter code placed immediately before a precipitation or obscuration code to modify or further describe the weather phenomenon being reported. Descriptors include codes such as TS (thunderstorm), SH (shower), FZ (freezing), BC (patches), BL (blowing), DR (drifting), MI (shallow), and PR (partial).

Context Anchor

Pilots encounter descriptors when reading the present-weather part of a METAR, such as weather reported as showers, blowing snow, or freezing rain.