What do steep precipitation gradients on an airborne weather radar screen likely indicate?

Steep precipitation gradients on an airborne weather radar screen are typically indicative of significant changes in precipitation intensity over a short horizontal distance, which often correlates with areas of strong turbulence and vertical windshear. These conditions are particularly common near the edges of thunderstorms or in rapidly developing convective activity.

While turbulence can be present in various weather conditions, the presence of steep gradients suggests that there is an active and potentially unstable atmosphere, which contributes to the likelihood of turbulence as the aircraft transitions through differing air masses. Vertical windshear, characterized by changes in wind speed and direction with altitude, is also associated with these steep gradients, as it can further enhance turbulence and affect the aircraft's performance.

The other choices relate to phenomena that do not typically correlate with steep precipitation gradients. For example, stable air masses generally produce uniform or smooth precipitation rather than the sharp distinctions seen with steep gradients. Thunderstorm activity can indeed lead to steep gradients, but the direct association with turbulence and windshear emphasizes the aviation relevance here. Low visibility conditions can occur in various weather situations, but they aren't directly linked to the specific radar readout of steep gradients in precipitation.