The PSU/NCAR mesoscale model is a limited area, non-hydrostatic model (although it can also be run as a hydrostatic model), terrain following sigma coordinate model designed to simulate or predict mesoscale and regional scale atmospheric circulation. It was developed at Penn State and NCAR as a community mesoscale model and is continually being improved by contributions from users at several universities and government laboratories. The Fifth Generation NCAR/Penn State Mesoscale Model (MM5) is the latest in the series. Features include a multiple grid nesting capability, non-hydrostatic dynamics, a 4 dimensional data assimilation capability (4 dimensional nudging is currently being used) and more advanced physics options for a better treatment of smaller scale atmospheric circulations.
For more information about MM5 please visit: http://www2.mmm.ucar.edu/mm5/mm5-home.html.