An Extratropical Cyclone Atlas A Tool for Illustrating Cyclone Structure and Evolution Characteristics

Extratropical cyclones play a significant role in determining the day-to-day weather conditions in many parts of the world through their associated wind and precipitation patterns. The atlas has been created to explore the mean structure and evolution of the 200 most intense North Atlantic cyclones identified in 20 winters of the ERAInterim reanalysis data. The method used to create the composite fields is described in section 2. In sections 3 and 4, vertical and horizontal composites of cyclone structure for cyclones generated in the North Atlantic regions are used to subjectively identify features such as the relative positions of cold, warm, and occluded fronts and their associated wind and cloud patterns. At the same time, development of a closed isobar forms and the central pressure falls; cyclonic circulation and system-relative wind speeds around the cyclone center increase. The system-relative winds are computed by subtracting the propagation speed of the cyclone from the gridded winds for each individual cyclone before compositing.