Plain English Meaning
PO is the code used in a weather report to say that small spinning columns of dust or sand are forming on the ground near the airport.
Full Definition
In a METAR, PO is the weather phenomenon code reported when well-developed dust or sand whirls are observed at or near the station. These are small, rotating columns of air made visible by the dust or sand they pick up from the surface, typically forming on hot, dry days when strong surface heating creates rising air that begins to spin. They are reported under the present weather group of the METAR.
Context Anchor
Seen in the present-weather part of a METAR, where short codes describe weather observed at or near the airport.
Derivation
PO comes from the French "poussière," meaning "dust." Aviation weather codes were standardized internationally, and several abbreviations to French because of its historical role in international and .