During 1951-2009, 47% of all tropical systems (TSs) within the Atlantic Basin transitioned to post-tropical (PTC) extratropical classification. These systems have shown the capability of producing hurricane-force winds and gusts for portions of the eastern United States. This study provides a climatological foundation for high-wind observations that were contributed from PTCs. In this study, 76 PTC systems were identified and tracked using six hourly observations from the National Hurricane Center’s HURDAT dataset. Mean wind radii buffers were calculated and used to determine the high-wind observations attributed by PTCs. High-wind climatology was developed by using hourly surface wind data from the National Climatic Data Center (NCDC) and deploying the current NWS high-wind criteria. For this study, the geography and climatology of PTCs and resultant high winds were analyzed using geographic information systems (GIS). Findings show that < 1% (270) of all high-winds events that occur within the U.S. were contributed from PTCs. The highest frequencies were found in three regions: Midwest, Mid-Atlantic, and New England. Due to the low number of high-wind events produced from PTCs, an adjusted wind scale was created by using standard deviations of sustained and gust observations. The goal of this study is determine the contribution of high winds from PTCs, with the aim of improving our understanding of the hazardous outcomes of such events.

A quantitative description of wind-wave and wind-current momentum transfer in high wind conditions is currently unresolved, mainly due to the severe character of the problem. It is, however, necessary for accurate wave models, storm and hurricane forecasting, and atmosphere-ocean model coupling. In this research, strongly forced wind-wave conditions were simulated in a laboratory tank. On the air side, a static pressure probe mounted on a vertical wave follower measured wave-induced airflow pressure fluctuations in close proximity to the surface. Vertical profiles of wave-induced pressure fluctuations were resolved and wave phase dependent features, such as airflow separation, identified. Based on the pressure measurements, wind-wave momentum fluxes were obtained. The dependence of the spectral wave growth function on wind forcing, wave steepness, and wave crest sharpness was also investigated. The bulk air-sea momentum fluxes were estimated using the "total budget" experimental technique. It provided information on the contribution of a wind-wave flux induced by a single wave to the total air-sea momentum flux. The percentile contribution of wind-wave momentum flux into one wave was found to be dependent on the wave's steepness. An arbitrary change in steepness, however, was found to modify the wave field in such a way that it had little effect on the total wind stress. To complement wind stress measurements velocity profiles in the water were measured using Particle Image Velocimetry technique. Mean current, turbulent stress, turbulent kinetic energy and turbulent dissipation rate vertical profiles were studied as a function of wind speed. Together with wave spectrum evolution measurements they form a complete empirical description of momentum fluxes in the laboratory tank. The results provide a detailed empirical view on airflow pressure fluctuations over a wavy surface, on total wind stress, and on the velocity response in the water. A new wave growth parameterization with wind forcing range extended into storm conditions is the most significant stand alone result of this work. Combined with the near surface vertical profiles, these empirical data also serve as a test bed for coupled air-sea numerical models.