Changes in the low-level kinematic and thermodynamic structure of Hurricane Alicia ( 1983) at Landfall.

Abstract

Aircraft, land station, and buoy data were composited with respect to the center of Hurricane Alicia 81983) for 3 8h periods corresponding to prelandfall in the open Gulf of Mexico, landfall in the Galveston area, and postlandfall in the vicinity of Houston. This emphasizes the land-sea frictional asymmetry at landfall. The asymmetric structure of the surface wind field may be interpreted as having resulted from the combined effects of land-sea roughness differences, background environmental flow, and storm translation. The land-sea frictional difference acted to oppose the mean vortex flow over land and reinforce it over water. Analyses of temperature, dewpoint, and equivalent potential temperature indicate that loss of the oceanic heat and moisture source, combined with advection of drier air on the landward side of the storm, was responsible for cooling and drying of the inflowing boundary layer air. Upon introduction of this air the core convection and vertical ascent, a decrease in the release of latent heat could then lead to cooling in the middle levels of the storm and a subsequent increase in the central sea-level pressure.-from Author