What was the weather change noted at Harrison (KHRO) between given times?

The answer identifies a specific weather event that occurred at Harrison (KHRO), highlighting the onset of thundershowers at 12 minutes past the hour. This is significant as it indicates a substantial change in weather conditions, typically associated with the development of more intense weather phenomena, including potential hazards for flight operations.

Thundershowers can affect various factors critical for aviation, such as visibility, turbulence, and precipitation intensity. The exact timing of this change can also help in understanding the progression of weather in the area, enabling dispatchers and pilots to make informed decisions regarding flight safety and route adjustments.

While other options mention various elements of weather changes, such as cloud cover or visibility, identifying the active development of thundershowers reflects a more dynamic and immediate change in the weather environment that can have direct implications on flight operations.