Which weather advisory covers less severe weather compared to a SIGMET?

The correct answer is AIRMET. An AIRMET (Airmen’s Meteorological Information) is specifically designed to inform pilots of weather conditions that may be hazardous to aircraft operations, but are generally less severe than those described in a SIGMET (Significant Meteorological Information).

SIGMETs alert pilots to severe weather phenomena such as thunderstorms, severe turbulence, or icing that can significantly impact flight safety. In contrast, AIRMETs address weather conditions that are less intense, including moderate turbulence, widespread precipitation, or lower ceilings and visibility that could still pose a risk, particularly to small aircraft or inexperienced pilots.

The other options do not fit the criteria of the question as follows: METAR is an aviation routine weather report, which provides observable conditions at an airport but does not classify weather severity. FA refers to Flight Advisories, which are general weather forecasts rather than specific advisories about hazard levels. ATIS (Automatic Terminal Information Service) broadcasts recorded information about weather and other important operational data to arriving and departing aircraft at an airport but does not function as an advisory like an AIRMET or SIGMET.