Which is NOT one of the impending signs of pre-flashover conditions?

The recognition of pre-flashover conditions is crucial for ensuring the safety of both firefighters and any occupants in a burning structure. Among the signs that indicate these conditions, thick and turbulent smoke, high heat, and roll-over are all associated with an imminent flashover.

Thick, turbulent smoke typically signifies a heavy volume of combustible gases and reduced visibility, indicating that the fire is growing and potentially approaching flashover. High heat is another critical sign; temperatures rise significantly as more oxygen feeds the fire, creating a dangerous environment. Roll-over, which is the ignition of gases accumulating near the ceiling, also indicates severe heat and the potential for rapid fire spread.

On the other hand, gusts of wind are not classified as an impending sign of pre-flashover conditions. While they can affect fire behavior and may exacerbate the situation by feeding the fire with additional oxygen, gusts themselves do not represent the critical thermal indicators or combustion conditions that indicate an approaching flashover. Therefore, identifying gusts of wind as the option that does not align with pre-flashover signs makes sense in the context of fire behavior and safety protocols.