FAA Commercial Pilot Airplane (CAX)WeatherMedium
A pilot is conducting a preflight weather briefing and notes a Convective SIGMET (WST) for an area. What type of weather phenomenon would qualify for a Convective SIGMET issuance?
- AWidespread areas of severe turbulence.
- BModerate icing at 10,000 feet MSL.
- CEmbedded thunderstorms or a line of thunderstorms.
- DVolcanic ash clouds affecting flight levels.
Show answer & explanationAnswer & explanation
Correct answer: C. Embedded thunderstorms or a line of thunderstorms.
Convective SIGMETs are specifically issued for hazardous convective weather that is significant to the safety of all aircraft. This includes severe thunderstorms, which are characterized by phenomena such as tornadoes, hail 3/4 inch or greater in diameter, wind gusts 50 knots or greater, or embedded thunderstorms, a line of thunderstorms, or thunderstorms producing heavy precipitation that affects 40% or more of an area at least 3,000 square miles.
Why the other options are wrong
- A. Incorrect; widespread severe turbulence would be covered by a non-convective SIGMET, not a Convective SIGMET.
- B. Incorrect; moderate icing would be covered by an AIRMET Zulu, not a Convective SIGMET.
- D. Incorrect; volcanic ash would be covered by a non-convective SIGMET, not a Convective SIGMET.
Convective SIGMET (WST)
An in-flight weather advisory issued for hazardous convective weather that is significant to the safety of all aircraft.
- Issued hourly for specific criteria of severe thunderstorms.
- Criteria include tornadoes, large hail, strong winds, and organized thunderstorm activity.
- Valid for 2 hours, or until superseded.
Memory trick: Convective SIGMET: Thunder's Top Threats.