But be aware that different types of data must be displayed by different programs. Here is a description of the different data files and the programs that allow you to display them. In later sections, the different types of data and programs are discussed in more detail. For example, hourly data files have the two-digit year, month, day, and hour in the file name. So don't type the y 's and d 's, substitute the appropriate dates and times.
Surface data Useful surface data programs include sfmap and, less commonly, sfgram .
Explaining the intricacies of sfgram is beyond the scope of this document, but you can use sfmap to plot surface weather maps. Ideally, both types of files will have identical data, but in practice you can sometimes find data in one file but not the other. While you may like to look at data from the future, there's not much available, and the future can change without warning. This tells Gempak to plot all data from that data set that fits within garea . This parameter controls not only what gets plotted at the station, but how big the symbols and wind barbs are.