Sunday, 22 January 2012
A Climatological Perspective of Tornado Outbreaks Spawned by Landfalling Tropical Cyclones Across the Eastern United States
Hall E (New Orleans Convention Center )
Tropical cyclones (TCs) typically spawn tornadoes in their right forward quadrant upon making landfall. Much variability, however, exists in the number and intensity of these tornadoes. For example, some TCs have generated extraordinary tornado outbreaks (e.g. Ivan 2004) while others did not produce any tornadoes at all. In this study, the tornadoes associated with 54 TCs are examined to determine what aspects of the synoptic-scale atmospheric environment most effectively distinguish between the number and intensity of tornadoes spawned. Archived lower tropospheric map analyses, atmospheric soundings, HYSPLIT back trajectories, and water vapor imagery are examined along the path of each TC to identify atmospheric environments (e.g. instability and high wind shear) that promote or hinder tornadogenesis. From this analysis, a conceptual model is developed that ties these environments to various TC attributes (e.g. size, strength, speed of movement) and interactions between the TC and the larger-scale, extra-tropical circulation into which the TC is approaching. Preliminary work reveals that the most prolific tornado outbreaks are spawned by relatively slow-moving TCs that make landfall along the Gulf Coast and maintain a strong upper-level circulation after tracking inland.