The Evolution of Hurricane Humberto (2001)

Abstract

Abstract In 2001, the National Oceanic and Atmospheric Administration and the National Aeronautical and Space Administration marshaled their resources to sample Hurricane Humberto for 3 successive days during the fourth Convection and Moisture Experiment (CAMEX-4). Humberto developed from a tropical storm into a category-2 hurricane despite the deep-layer vertical shear of the environmental horizontal wind (VWS) increasing markedly on the second and third days of sampling. As exhibited in earlier studies, the eyewall convection developed an azimuthal wavenumber-1 (n = 1) asymmetry as the VWS increased. Horizontal divergence and vertical stability within 100 km of the eye exhibited persistent relationships to the VWS vector. The warm core evolved in an unexpected way. The warm anomaly was initially located in the lower troposphere and built upward as the storm intensified. The maximum temperature anomaly remained in the lower troposphere on all 3 days while the development of the upper-tropospheric warm anomaly appeared to be inhibited by the increasing VWS and the entrainment of dry environmental air into the core at midlevels. The warm core of this higher-latitude (33°N) storm displayed large differences when compared to most numerical simulations, wind-induced surface heat exchange theory, and observations of tropical cyclones in the deep tropics acquired nearly 50 years ago. The results were similar to some recent numerical simulations.