Erica's Answer:A dry line is a sharp contrast in dewpoints across a very small distance in land mass. But, this difference in dewpoints is not caused by a cold front or warm front moving through the area. Here's a hypothetical dry line scenario from western Texas, where I used to work in TV weather! In Midland, TX, the dewpoint is 35 degrees. In Abilene, TX, 150 miles to the east of Midland, the dewpoint is 68 degrees. The strong contrast in the moisture content between Midland and Abilene is the dry line. Why do we care about dry lines? Well, when a dry line develops, it often provides the energy needed for thunderstorm development. It's basically like a mini- cold front has formed. Strong thunderstorms, even severe thunderstorms, usually form along the dry line.