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Advisories & Warnings

These services provide critical alerts for hazardous weather conditions affecting flight safety.

Significant Meteorological Information (SIGMET)​

SIGMETs provide information concerning the occurrence or unexpected occurrence of weather phenomena that may affect the safety of aircraft operations (e.g., severe turbulence, icing, dust storms).

Volcanic Ash​

  • Volcanic Ash Advisories (VAA): Issued by 9 nominated Volcanic Ash Advisory Centres (VAACs) globally. They coordinate information on ash clouds that endanger aviation.
  • Volcanic Ash Graphic (VAG): A graphical representation of atmospheric volcanic ash clouds. Note: Only Wellington issues a VAG at this time.

Tropical Cyclone Advisories (TCA)​

Issued by specified centres around the world every six hours when there is an active tropical cyclone.

Space Weather Advisory​

Issued when impacts are expected to:

  • HF communications
  • Satellite communications
  • GNSS-based navigation and surveillance systems
  • Heightened radiation levels

Content:

  • Type of impact
  • Expected onset and duration
  • Spatial extent
  • Severity (Moderate or Severe)