The Pennsylvania State University-National Center for Atmospheric Research mesoscale model MM5 is used to simulate Hurricane Erin (2001) at high resolution (4-km spacing) from its early development as a tropical depression on 7 Septmber, through a period of rapid intensification into a strong hurricane (8-9 September), and finally into a stage during which it maintain its intensity on 10 September. These three stages of development, intensification, and maintenance in the simulation are in good agreement with the observed evolution of Erin. Comarisons of observed and simulated tracks, intensities, wind and precipitation patterns are remarkably good. Of particular interest in this study is the model's ability to capture a transition in storm's intensity and structure between 9 and 10 September during which time the hurricane's intensification suddenly ends and its outer precipitation bands shift approximately from the northeastern to the western side of the storm. The effects of the vertical wind shear on the changes of the precipitation structure are dicussed.