Wind Speed Changes of North Atlantic Tropical Cyclones Preceding Landfall

Abstract

Landfalling tropical cyclones have been extensively researched, especially their degradation upon coming ashore and the hazardous weather they create along coastlines and farther inland. Many of the factors that weaken storms over land could begin to act when they are still at sea, yet prelandfall intensity change remains poorly documented. This study examined the consistency of prelandfall changes in tropical cyclone intensity throughout the North Atlantic Ocean from 1950 to present. On average, cyclones intensified by 3 m s 21 less in their final 12 h before landfall than in the 12 h preceding those, on both mainland shores and in the Greater Antilles, while smaller islands showed no such change. Contributions of increasing storm age and poleward movement to this reduction were negligible. Two possible contributing factors to declining intensification before landfall were examined. The presence of a spring-neap tidal pattern of ;2 m s 21 in the prelandfall decline is consistent with tidal mixing influencing ocean temperature on the continental shelf. The tendency for the decline to be greater at night suggested the possible influence of solar heating on tropical cyclones near shore.

Tropical cyclone rainfall over Puerto Rico and its relations to environmental and storm‐specific factors

“…It is important to note that the mean vertical wind shear in the Atlantic for the hurricane season peak months is westerly with a magnitude greater than 8 ms −1 over much of the basin (Goldenberg and Shapiro, ).The El Niño Southern Oscillation and Saharan air layer can influence the vertical wind shear in the Atlantic by changing the direction and intensity of the wind which can then affect TC development and intensification (Gray, ; Dunion and Velden, ). The vertical wind shear in the Caribbean is also highly influenced by the tropical upper‐tropospheric trough (TUTT), which can have both detrimental and favourable effects on TCs cyclogenesis and intensification (Sadler, ; Yaukey, ) In its average position, the TUTT is located north of Puerto Rico with its southern portion associated with stronger vertical wind shear affecting TCs over the eastern Caribbean region (Fitzpatrick et al , ).…”

Tropical cyclones in the North American Regional Reanalysis: An assessment of spatial biases in location, intensity, and structure

“…Finally, both the NARR and CFSR data sets display a statistically significant positive relationship between intensity and distance to the U.S. coastline during the tropical portion of the lifecycle, a result that is expected based on previous work [Schenkel and Hart, 2012]. The BT intensities do not exhibit this trend, instead showing a slight tendency to de-intensify when approaching the U.S. coastline, which complements results in Yaukey [2011], in which storm intensification rates declined in the 12 h preceding landfall.…”

“…There is no special consideration for a tilted vortex with height, as we expect that asymmetries relating to vertical wind shear and/or storm motion will be smoothed during the compositing process. We compare these composite TC structures with theoretical and observational work (for example, the classic structural composites of Hawkins and Rubsam [1968] and Frank [1977] and recent modeling and theoretical studies by Stern and Nolan [2009, 2011).…”

The Spatial Characteristics of Hourly Rainfall Induced by Tropical Cyclones Along the South China Coast

“…The high intensity TC type mostly appears along the coastline and gradually decreases towards the inland areas. This is attributed to the fact that tropical cyclones tend to weaken after making landfall due to reduced energy supply and increased frictional effects (Yaukey, 2011). Generally, the TCs with higher intensities can induce more extreme rainfall in the region (Knight & Davis, 2009;Rao & Macarthur, 1994).…”