Definition
Significant weather phenomena that are not produced by thunderstorm activity, including severe icing, severe or extreme turbulence, dust storms, sandstorms, and volcanic ash, which can hazard aircraft operations and are reported in SIGMETs.
Plain English
Dangerous weather that isn't caused by thunderstorms — things like heavy icing, strong turbulence, blowing dust or sand, and volcanic ash.
Context Anchor
Seen in SIGMET discussions, where the FAA separates thunderstorm-related hazards from other serious weather hazards along a route.
Derivation
Non-' means 'not,' and 'convective' refers to convection — the vertical movement of air that builds thunderstorms. So 'nonconvective' simply means weather hazards that come from something other than thunderstorm activity.
Why Pilots Care
Helps pilots select appropriate weather advisories and anticipate different hazards like icing in layered clouds versus turbulence in storms.
Grounding Statement
A route can look free of thunderstorms and still have nonconvective weather that makes the flight hazardous.
Intuition Check
Do not read nonconvective as “not important weather.” It only means the hazard is not caused by thunderstorm-type vertical air movement.
Example Sentence 1
The briefer issued a nonconvective SIGMET for severe icing between 8,000 and 14,000 feet along the planned route.
Example Sentence 2
Pilots should check for nonconvective SIGMETs when widespread stratus is forecast rather than isolated thunderstorms.