Plain English Meaning

A weather warning sent to pilots in flight about conditions dangerous enough to threaten any aircraft, like severe icing, severe turbulence, dust storms, or volcanic ash.

Full Definition

An in-flight weather advisory issued by the National Weather Service to warn pilots of weather phenomena considered hazardous to all aircraft, regardless of size or type. Sigmets cover severe icing not associated with thunderstorms, severe or extreme turbulence or clear air turbulence not associated with thunderstorms, dust storms or sandstorms lowering to below three miles, and volcanic ash. , issued separately, cover -related .