of time. Then this data that needed to be taken over a longer period of time gets placed into FDDA. It is also utilized for dynamical initialization and four-dimensional data sets. Most importantly, MM5 is well documented and has many places for user support. Functions There are many pieces of the MM5 modeling system, each with different functions. These pieces include: TERRAIN, REGRID, LITTLE_R, NESTDOWN, INTERPF, INTERPB, and GRAPH/RIP. In the basic sense, the model begins by taking the information and then makes a model of the land. This is done by using the piece TERRAIN. Then, the model guesses the different pressures that exist in the atmosphere throughout this plot of land, which is done through REGRID. Then, the model takes these guesses, and with the help of some surface observations, can create an objective analysis, using LITTLE_R. RAWINS is an older version of LITTLE_R and thus LITTLE_R is more commonly used. Then INTERPF takes that data from RAWINS/LITTLE_R and REGRID to interpolate that data to the sigma coordinate explained above. MM5 itself computes the time combination. The NESTDOWN function has the ability to change the vertical sigma levels. INTERPB generates the first guess for RAWINS, as well as gathers the files used to make guesses for REGRID. Finally, GRAPH/RIP generates the plots that users can view from all of the data given from the other programs. RIP stands for Read/Interpolate/Plot, and it uses NCAR Graphics to help envisage the output from the MM5. Memory and code basics MM5 is written in FORTRAN. These FORTRAN programs must be compiled on a local computer, and some need to be recompiled each time a model configuration is changed. The program uses pointers to assign variables to values. These pointers go into parts of the memory to assign specific values to the desired variables. MM5 can also perform multiple tasks at once. Specifically, two different tasks can be executed on different processors simultaneously and MM5 uses this as much as possible. This multi-tasking also uses nesting, and MM5 allows up to nine domains (processes) running at the same time and they interact throughout the whole process . The model utilizes two-way nesting, which occurs when the input from one nest's coarse mesh, which is a high density of cells in one area, comes from one of the four boundaries, but the feedback to the coarser mesh happens through the nest interior. Each