[--MAIN HOME--] [--ALL HABYHINTS--] [--FACEBOOK PAGE--] CONTINENTAL TROPICAL AIR MASS METEOROLOGIST JEFF HABY The source region for cT air is the desert Southwest, the high plains and Mexico with relation to the United States. The air has low dewpoints and warm to hot afternoon temperatures but with mild nighttime temperature. Skies are generally clear in cT air. This allows daytime heating during the day and radiational cooling at night. The cT air mass is most prevalent in summer; in the cool season it is not as discernible. Due to the buoyancy and elevation of cT air across North America, this air will advect into the mid-levels of the atmosphere once it moves out of its source region. This creates a cap of mild dry air. If this air advects over PBL mT air, the severe thunderstorm threat increases significantly. The boundary of cT is most noticeable with the creation of a dryline. A dryline separates mT air from cT air. Depending on the strength of the dryline, convergence along the dryline and the dynamics above the dryline, severe thunderstorms can form near a dryline boundary.