FAA Instrument Flight Instructor (FII)WeatherHard
A flight service specialist advises a pilot of an in-flight weather advisory covering a line of embedded thunderstorms producing surface hail 1 inch in diameter over a wide area. Which weather advisory has been issued?
- ASIGMET
- BAIRMET Sierra
- CConvective SIGMET
- DAIRMET Tango
Show answer & explanationAnswer & explanation
Correct answer: C. Convective SIGMET
A Convective SIGMET is issued for severe thunderstorms with surface winds ≥50 knots, hail at the surface ≥3/4 inch in diameter, tornadoes, embedded thunderstorms, lines of thunderstorms, or thunderstorms affecting 40% or more of an area of at least 3,000 square miles. Since hail here is 1 inch (exceeding the 3/4-inch threshold) and involves embedded thunderstorms, a Convective SIGMET is the appropriate product, not a standard SIGMET or AIRMET.
Why the other options are wrong
- A. A standard SIGMET covers severe icing, severe turbulence, dust storms, and volcanic ash, not thunderstorm-specific hazards like this.
- B. AIRMET Sierra covers IFR conditions and mountain obscuration, not thunderstorms.
- D. AIRMET Tango covers turbulence and sustained surface winds, not thunderstorm hail.
Convective SIGMET
An in-flight weather advisory for severe or embedded thunderstorms, lines of thunderstorms with hail ≥3/4 inch, surface winds ≥50 knots, or tornadoes.
- Issued for severe thunderstorm conditions specifically
- Valid for 2 hours, issued every hour with special updates
- Implies severe or greater turbulence, icing, and low-level wind shear
Memory trick: Convective SIGMET = 'Storms So Intense' with hail, wind, or tornadoes.