Plain English Meaning

WS is the label at the top of a weather warning that tells you it's a SIGMET about non-thunderstorm hazards — things like severe turbulence, severe icing, or widespread dust or volcanic ash. When you see WS in the header, you know the warning is serious and applies to every aircraft, not just small ones.

Full Definition

WS is the product identifier used in the header of a non-convective SIGMET issued by the National Weather Service. A SIGMET (Significant Meteorological Information) carrying the WS prefix warns of weather hazards considered significant to all aircraft, other than thunderstorms — specifically severe or extreme turbulence not associated with thunderstorms, severe icing not associated with thunderstorms, and widespread , , or volcanic ash lowering to less than three miles. The WS designator distinguishes these from (designated ) and from (designated WA).