A nonfrontal, narrow band of active thunderstorms that often develops ahead of a cold front is known as a?

The term you're looking for describes a nonfrontal, narrow band of active thunderstorms that commonly develops ahead of a cold front, and that is known as a squall line. Squall lines are typically characterized by a line of thunderstorms that can produce severe weather phenomena, including heavy rainfall, strong wind gusts, hail, and even tornadoes.

This situation often arises when warm, moist air is forced to rise over a cooler air mass at the surface, creating the conditions necessary for thunderstorm development. The intense lifting, combined with favorable wind shear, enhances the storm activity along the squall line.

In contrast, a prefrontal system refers to weather phenomena associated with the area just ahead of a cold front but does not specify the active thunderstorm component like a squall line does. A dry line is a boundary that separates moist and dry air, often associated with severe thunderstorms but is not specifically a line of thunderstorms. A warm front involves the gradual lifting of warm air over cooler air, leading to more widespread, less intense precipitation, rather than a narrow band of severe storms.

Thus, the squall line is specifically defined by its structure and association with severe weather along a narrow band, making it the correct answer.