What does smoke puffing in and out of a structure indicate?

Smoke puffing in and out of a structure typically indicates a fire that is experiencing rapid changes in intensity, often due to fluctuations in oxygen supply. This behavior can suggest that the fire is either in a ventilation-controlled state or that it is transitioning from a smoldering phase to a more intense burning phase. Observing this pattern can also signal potential flashover conditions, making it crucial for firefighters to assess the situation carefully for safety.