On Upper Tropospheric Kinematics and Severe Weather Occurrence

Upper tropospheric wind maxima and their associated divergence fields are examined in terms of severe weather occurrence. A two-part project is described. Part I involves examination of severe weather occurrences and divergence areas qualitatively evaluated in terms of upper tropospheric wind maxima quadrants and the curvature of the flow. Part II calculates synoptic-scale divergence directly from radiosonde wind data. These quantitative divergence estimates are compared with the location of upper tropospheric wind maxima, wave troughs and severe weather occurrence. It is concluded that regions of upper tropospheric divergence are present with the occurrence of severe weather and, in particular, with the occurrence of severe weather outbreaks. Several examples are presented to support the ideas discussed.