Published on: 12/17/2020 6:30:30 AM

A Dry Line can form along the boundary between hot, dry, continental tropical (cT) air and warm, moist, marine tropical (mT) air. Also called a 'Dew point front', sharp changes in dew point temperature can be observed across a dry line. Dry lines are usually found out ahead of cold fronts, where southerly and south-westerly winds bring subtropical air from the continental regions and marine regions into contact with one another.

Dry Line is an important factor in severe weather frequency in the Great Plains, USA. It typically lies north south across the central and southern high plains states during the spring and early summer, where it separates moist air from the Gulf of Mexico (to the east) and dry desert air from the south western states (to the west). The Dry line typically advances eastward during the afternoon and retreats westward at night. However, a strong storm system can sweep the dry line eastward into the Mississippi valley, or even further east, regardless of the time of day.

A typical dry line passage results in sharp drop in humidity (hence the name), clearing skies, and a wind shift from south or south-easterly to west or south-westerly. Blowing dust and rising temperature also may follow, especially if the dry line passes during the day time. These changes occur in reverse order when the dry line retreats westward. severe and sometimes tornadic thunderstorms often develop along a dry line or in the moist air just to the east of it, especially when it begging Moving eastward.