FAA Instrument Rating Airplane (IRA)Weather and Weather ServicesMedium
A pilot is briefed on a pre-frontal squall line expected along the route of flight. Which characteristic makes squall lines particularly hazardous to instrument flight?
- AThey produce steady light rain with little turbulence
- BThey often contain some of the most severe thunderstorms, with little or no warning
- CThey dissipate rapidly after sunset with no hazard to night flights
- DThey typically form well behind the associated cold front with weak winds
Show answer & explanationAnswer & explanation
Correct answer: B. They often contain some of the most severe thunderstorms, with little or no warning
A squall line is a non-frontal band of active thunderstorms that often forms ahead of a cold front. It frequently contains some of the most intense and long-lived thunderstorm cells, and because it is not tied directly to the frontal boundary, it can develop with little advance warning, making it a serious hazard for IFR flight.
Why the other options are wrong
- A. Squall lines produce severe, not light, weather with intense turbulence and precipitation.
- C. Squall lines can persist and even intensify at night, posing continued hazards regardless of time of day.
- D. Squall lines typically form ahead of (not behind) the cold front, often with strong, gusty winds.
Squall Line
A narrow band of active, often severe thunderstorms that forms ahead of an advancing cold front.
- Non-frontal band, typically forms ahead of a cold front
- Can contain severe thunderstorms with little advance warning
- Associated with strong gusty winds, hail, and severe turbulence
Memory trick: Squall line: 'Sudden and Severe, ahead of the frontal sleeve.'