Monday, 3 November 2014: 2:15 PM
University (Madison Concourse Hotel)
Storm aficionados have referred to hodographs that have a sharp change in the direction of the shear vector at low levels as "sickle" hodographs. The hodographs contain a sharp (typically ~90 degrees) clockwise turn of the shear over a short vertical distance, resulting in a kink in the hodograph, typically in the lowest kilometer, which stands in contrast to the smoothly curved composite hodograph of supercell environments. Above and below the kink in the sickle hodograph, the vertical shear is approximately unidirectional. The sickle hodograph has been associated with several high-end tornado events. What makes this hodograph special? This question is explored as part of a larger parameter space study of hodograph morphology, vertical wind shear distribution, and thermodynamic profiles to investigate how they influence the development and maintenance of low-level rotation in supercell thunderstorms. The dynamics of low-level rotation are investigated by tracing material circuits backward in time from initial positions surrounding the low-level mesocyclones.
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