A squall is defined as a sudden increase of at least 15 knots in average wind speed to a sustained speed of?

A squall is recognized in meteorology as a sudden and significant increase in wind speed, typically characterized by a rapid rise of at least 15 knots to a sustained wind speed. The defining criterion includes reaching an average sustained wind speed of 20 knots or more for a duration of at least 1 minute. This definition is important for pilots and dispatchers as squalls can signal rapidly changing weather conditions that may impact flight operations.

Understanding the specific threshold of 20 knots is crucial, as it helps in differentiating squalls from other types of wind increases, ensuring that flight crews can take appropriate precautions to maintain safety in potentially turbulent conditions. This particular sustained wind speed helps in assessing whether the weather phenomenon qualifies as a squall, which has implications for flight planning and safety procedures.

In this context, the other options present different sustained wind speeds that do not align with the established meteorological definition of a squall, making them incorrect in this scenario.