In this study, the formation and evolution of Tropical Storm Allison (2001) is successfully simulated using the Penn Stata-NCAR nonhydrostatic mesoscale model (MM5). The storm and surrounding deep convection are modeled with a fine grid mesh of 6 km and an explicit microphysics package. Model simulations with various microphysical, convective, and planetary boundary layer parameterization schemes are compared with surface, radar, and satellite observations to see which combination most accurately reproduces the development and early life of the system.

The MM5 model is used to gain an understanding of the mechanisms involved in the development and early structure of Allison. Of particular interest are boundary interactions in the Gulf of Mexico prior to the development of Allison and the role these interactions played in the storm's genesis. Another interest is the storm's apparent transition from a tropical system to a mid-latitude type system (i.e. an MCS or extratropical cyclone) early in its life cycle. With fine-scale model analyses, the detailed structure of the storm is probed and both of these issues are addressed.

Future research will investigate aspects of the system such as the especially intense rainfall over Houston on 8 and 9 June. The model setup for the current phase of research will serve as a platform for this work.