Poleward migration of tropical cyclone (TC) activities may increase TC risks for higher-latitude coastal regions. Here we show that the mean latitude of lifetime maximum size (LMS) of TCs has increased significantly at a rate of 0.92° per decade over the globe, approximately 70% faster than the poleward migration rate of lifetime maximum intensity (LMI). The accelerated LMS migration is associated mostly with the increased frequency and duration of post-LMI expansion. TCs undergoing post-LMI expansion tend to occur in environments characterized by strong vertical wind shear, which generally suppresses TC intensification but permits size expansion. As LMI shifts poleward into higher-latitude regions with enhanced climatological wind shear, the likelihood of post-LMI expansion increases, contributing to a growing latitudinal separation between LMS and LMI. These results demonstrate that TC size and intensity exhibit distinct responses to the poleward migration of TC activity, with important implications for assessing future TC risks at higher latitudes.
 

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