Recent Rebounding of the Post‐Landfall Hurricane Wind Decay Period Over the Continental United States.

FLORIDA; PERSIAN Gulf

The hurricane post‐landfall wind speed decay is closely linked to the inland damage potential. We introduce the wind decay period as a new metric for assessing the time required for a landfalling hurricane to dissipate to the intensity below tropical storm strength. In the continental United States, the wind decay period was generally decreasing during 1900–1979 but significantly increased during 1980–2019. The 120‐year trend pattern of the wind decay period has been found to be correlated with the Atlantic Multidecadal Oscillation. Meanwhile, we show that the storm's distance of movement is not changing simultaneously with the decay period due to the variance of storm translation speed. The spatial variation of the wind decay is also confirmed. While the majority of the historical Gulf landfall hurricanes decayed below tropical storm strength, landfalling hurricanes over Florida in particular, tend to cross the peninsula retaining wind speeds greater than 34‐kt. Plain Language Summary: The destructive forces from a hurricane can penetrate far inland. The wind speed decay after hurricanes making landfall is critical for estimating potential inland damages. We introduce the wind decay period as a measurement of the time required for a landfalling hurricane to decay below tropical storm strength. The wind decay period helps quantify the longevity of the storm moving inland at a certain intensity. With the focus on the period 1900–2019, hurricanes making landfall over the continental United States show a decrease of longevity before 1980 but significantly increase thereafter. This trend shows a relationship to the Atlantic Multidecadal Oscillation. Meanwhile, the distance of the storm moving over land is not increasing with longevity, indicating the variance of the storm's speed of movement also plays an important role. Spatial variations exist where landfalling hurricanes over the Atlantic East coast and Florida peninsula are likely to turn back to the ocean without decaying to below the tropical storm strength. Key Points: The wind decay period and decay distance are introduced to quantify the longevity of an inland moving tropical cyclone at a certain intensity levelPrior to 1980, hurricanes making landfall over the continental United States show a downward trend of the wind decay period but rebounds significantly after 1980A possible correlation between the hurricane wind decay period and the Atlantic Multidecadal Oscillation is found [ABSTRACT FROM AUTHOR]

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