Analysis of near-surface wind flow in close proximity to tornadoes

Results from numerical tornado simulations indicate that variations in near-surface inflow have a profound impact on vortex structure and intensity, providing motivation to collect near-surface wind measurements in/near tornadoes. Since 2008, the Tactical Weather Instrumented Sampling in/near Tornadoes EXperiment (TWISTEX) has collected wind measurements in close proximity to at least five tornadoes using mobile mesonet stations, and in one of these events, an in situ instrument was deployed to make direct or near-direct wind measurements within the tornado core. These tornadoes were well documented, presenting an opportunity to analyze the near-surface wind flow near each tornado.

In each case, a detailed analysis of the tornado track, visual vortex structure, and vortex intensity will be presented. The detailed track records will be used to transform near-surface velocity measurements onto a tornado-relative grid, from which estimations of decomposed velocities (radial and tangential) will be made. Where possible, the temporal evolution of these decomposed velocities will be related to the visual vortex structure and intensity, which may provide some insight into the life cycle of these tornadoes.