Windstorms Intense windstorms in the Northeastern United States F. Letson1, R. J. Barthelmie2, K.I. Hodges3 and S. C. Pryor1 1Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, New York, USA 5 2Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York, USA 3Environmental System Science Centre, University of Reading, Reading, United Kingdom Correspondence to: F. Letson (
[email protected]), S.C. Pryor (
[email protected]) Abstract. Windstorms are a major natural hazard in many countries. Windstorms Intense windstorms during the last four decades in the U.S. Northeast are identified and characterized using the spatial extent of locally extreme wind 10 speeds at 100 m height from the ERA5 reanalysis database. During all of the top 10 windstorms, wind speeds in excess of their local 99.9th percentile extend over at least one-third of land-based ERA5 grid cells in this high population density region of the U.S. Maximum sustained wind speeds at 100 m during these windstorms range from 26 to over 43 ms-1, with wind speed return periods exceeding 6.5 to 106 years (considering the top 5% of grid cells during each storm). The propertyProperty damage associated with these storms, (inflation adjusted to January 2020,) is ranges 15 from $24 million to over $29 billion. Two of these windstorms are linked to decaying tropical cyclones, three are Alberta Clippers and the remaining storms are Colorado Lows. Two of the ten re-intensified off the east coast leading to development of Nor’easters. These windstorms followed frequently observed cyclone tracks, but exhibit maximum intensities as measured using 700 hPa relative vorticity and mean sea level pressure that are five to ten times mean values for cyclones that followed similar tracks over this 40-year period.