An examination of extreme cold air outbreaks over eastern North America

Abstract

In the first outbreak, surface cyclogenesis occurs prior to the outbreak onset (local 850 mb temperature decreases). Regions of strong cold air advection and adiabatic warming are found immediately upstream of the cyclone over the cold air outbreak area. Since the two regions are nearly superimposed, the effect of advective cooling is partially opposed by adiabatic warming. In the second outbreak, surface cyclogenesis follows the outbreak onset. In this case, local and advective cooling is observed over a larger region as a cold air pool over central Canada is transported southeastward. It is hypothesized that the intensity of cold air outbreaks over eastern North America is proportional to the areal coverage of the cold air advection region and timing, relative to cold air advection onset, of surface cyclogenesis. -from Authors