What is a Dry Line (DL)?

A dry line is a weather phenomenon that occurs when a sharp boundary forms between dry and moist air masses. It is most commonly found in the Great Plains of the United States, where dry desert air from the west meets moist Gulf air from the east. This contrast in air masses creates a prime environment for severe thunderstorms and tornadoes.

Dry lines are most active in the spring and early summer when temperature and moisture differences between air masses are most pronounced. During the day, as the sun heats the land, the dry line moves eastward, pushing the moist air upward and often triggering thunderstorms. At night, it tends to retreat westward.

Meteorologists closely monitor dry lines because they can be a catalyst for dangerous weather, including supercell thunderstorms and tornado outbreaks. When a dry line is present, conditions can escalate rapidly, making it crucial for residents in tornado-prone areas to stay alert to weather updates.