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Information issued by a meteorological watch office concerning the occurrence, or expected occurrence, of specified en route weather phenomena that may affect the safety of low-level aircraft operations and was not already included in the forecast issued for low-level flights in the flight information region or subarea (ICAO). AIRMETs deal with weather of less severity than that covered by SIGMETs (significant meteorological information) or convective SIGMETs. AIRMETs cover moderate icing, moderate turbulence, sustained surface winds of 30 knots or more, widespread areas of ceiling less than 1000 ft (300 m) and/or visibility less than 3 miles (5 km), and extensive mountain obscurement.
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