Translation speed slowdown and poleward migration of western North Pacific tropical cyclones

Detecting and interpreting long-term changes in typhoon translation speed in observations remains challenging, contrasting with increased confidence in the poleward migration of typhoons. Here, I show a significant relationship between the basin-wide translation speed and the latitudinal position of tropical cyclones in the western North Pacific over 1980–2023. First, because tropical cyclones move faster at higher latitudes, the significant poleward migration (80 km/decade) increases the yearly basin-wide translation speed by 5% over the period. This effect reduces the detectability of a slowing trend. Second, the basin-wide translation speed solely contributed by regional translation speed has slowed by 18%, mostly in the late stage of the cyclone lifecycle. The translation speed slowdown and the poleward migration are likely caused by the same climate drivers through the interconnected large-scale atmospheric circulation between the tropics and subtropics. My findings suggest exacerbated tropical cyclone-related risk in the subtropical regions in a changing climate.