Grib support, particularly when it comes to scripting. This would be a huge asset for the program. Being able to write up scripts, and export model data would make this program the ultimate all round weather tool

Some customization of the hurricane model tracks, being able the adjust the plot thicknesses.
Not sure how much of a challenge it would be, but the placement of the isopleth labels in the isopleths instead of at the end would be awesome.