Study of the Dissipation of Hurricane Gertrude (1974)

Abstract

Meteorological events in the upper and lower troposphere in Hurricane Gertrude and vicinity are examined for causal effects related to the sudden dissipation of Hurricane Gertrude. Mesoscale and synoptic-scale meteorological observations reveal that the hurricane rapidly decreased in intensity as it overtook a westward propagating upper tropospheric trough. Quantized radar observations are presented, which show the marked decrease in storm-generated precipitation which occurred as Gertrude approached the vicinity of this trough. This study indicates that the dissipation of Gertrude resulted from large vertical wind shear and upper level synoptic-scale convergence with accompanying subsidence in the upper troposphere in the vicinity of the storm. The marked decrease in convective activity and storm organization occurred in spite of favorable sea surface temperatures, favorable lower troposphere stability, and convergence of air toward the storm center in the boundary layer. This study reveals the amount of control that upper atmospheric motion has on storm development.