The strong winter storm crossed from the west to east of the Sea of Japan developing rapidly in early April, 2012. The minimum pressure of the winter storm reached 964 hPa at 21:00 on 3rd April. The storm generated wind waves more than 10 m in the significant wave height and gave severe damages to coastal structures. This study analyzed observed wave records at 12 stations along the Sea of Japan. A series of numerical analysis was performed to understand the characteristics of extreme wave sea condition. The maximum wave heights were estimated based on the spectral wave model and nonlinear short wave statistical theory. The estimated maximum wave heights by the nonlinear theory show better agreement with the observed peaks of maximum wave height than that by the linear theory.
