SIGMET
urn:aero:airm:1.0.0:ConceptualModel:Subjects:AirTrafficOperations:InformationServicesProducts:MeteorologicalInformationProduct:SIGMET
Information issued by a meteorological watch office concerning the occurrence or expected occurrence of specified en-route weather phenomena which may affect the safety of aircraft operations.
Source:
ICAO,ICAO Annex 3,