Influence of hurricane-related activity on North American extreme precipitation



Despite the catastrophic societal costs of hurricanes and considerable recent attention to possible trends, little is known about the general contribution of hurricane-related activity to extreme precipitation over North America and the underlying dynamics. Here, a 25-year observational analysis of daily data shows important contributions to extreme events over large regions of North America, including a pronounced signal over northern and inland areas, with an average span of influence extending to several hundred kilometers. Over large areas of the Northeast, there are stations where more than two-thirds of all extreme events are linked to hurricane-related activity. Large-scale vertical velocity, maximum wind speed, and tropical/extratropical character are shown to be important factors in the strength and range of influence. Analysis of dynamical factors, including buoyancy, moisture availability, and lifting, show the largest changes in lifting, with rising motion typical of the deep tropics occurring over inland and northern latitudes.