What does DRSN indicate on a METAR?

The indication of "DRSN" on a METAR report signifies "drifting snow." METAR is an aviation weather reporting format that includes various observed phenomena, and specific codes are used to represent different weather conditions. The "DR" prefix stands for drifting, and "SN" is the code for snow. When conditions include snow that is being blown or drifted by the wind, this code is applicable and alerts pilots and air traffic controllers about potentially hazardous conditions related to reduced visibility and runway conditions.

In this context, drifting snow can significantly impact flight operations, as it often leads to lower visibility and can accumulate on surfaces, affecting taxiing and takeoff procedures. Understanding these codes is crucial for safety in aviation operations, particularly when planning for takeoffs, landings, and ground movements in winter weather conditions.