Which weather phenomenon signals the beginning of the mature stage of a thunderstorm?

• A. Precipitation beginning to fall
• B. Lightning ceases
• C. Skies clear
• D. Dense fog forms at the surface

Answer: (A)

Precipitation beginning to fall signals the mature stage of a thunderstorm. As a storm develops, strong updrafts lift moisture high into the cloud, and then downdrafts form as those droplets grow and fall. When rain, hail, or other precipitation finally reaches the ground, it shows that the storm has enough energy and vertical motion to sustain both updrafts and downdrafts—the hallmark of the mature phase. Before this point, you’d have updrafts without surface rain (the early cumulus stage). Afterward, the storm tends to begin weakening as downdrafts dominate and precipitation tapers off. So the onset of rain at the surface is the clear indicator that the storm has become mature.