Dry lines

Dry lines are boundaries that separate the moist air mass from the dry air mass. Severe thunderstorms may form along or just to the east of drylines. Dry lines are typically found east of the Rocky Mountains. Dew point temperatures may drop by as much as 16 degrees F along a dry line. Along a cold front, in the warm sector where moist air encounters dry air, convergence and lifting can occur--the drier air behind  the dry line lifts the moist air ahead of it. Thunderstorm development is thus triggered.  It is fairly common for supercells to develop along dry lines.  In Texas, tornadoes sometimes are created due to the uplifting caused by the outflowing cold air. 
Concept Mapping Toolkit
Insitute for Human and Machine Cognition
The University of West Florida