The evolution of low-wavenumber vorticity during rapid intensification: A dual-Doppler analysis

Ten unique three-dimesional dual-Doppler wind fields collected over a 6 h period on 2 August 1997 in eastern Pacific Hurricane Guillermo are used to document evolution in the low-wavenumber vorticity during rapid intensification. Preliminary results indicate that the vorticity structure across the eye and eyewall initially resembled a hollow tower supportive of barotropic/baroclinic instabilties. At subsequent time periods, prominent perturbation vorticity structures were observed to develop and amplify. Currently, comparisons between radar animations and the evolution of the decomposed perturbation vorticity fields is being used to verify the temporal continuity of the prominent asymmetric structures. The observed evolution will be compared to numerical simulations and theoretical expectations, including the most unstable modes and their azimuthal propogation speeds.