The Next Generation Air Transportation System (NGATS) planning horizon is 2025. In order to attain the NGATS objectives by that year, significant steps in that direction must be taken in the intervening years. A major milestone along the way will be the achievement of an Initial Operational Capability (IOC) circa 2012. This paper puts forth the principal components of the weather IOC—essentially a limited operational deployment. The IOC is the set of capabilities of NGATS Network-Enabled Weather (NNEW) which are planned for operational implementation by 2012. It is a tool to enable the Weather Integrated Product Team (IPT) to analyze, study, plan, budget for, and work towards the NNEW IOC. It also provides a documented vision with which the Weather IPT can convey to the other Joint Planning and Development Office IPTs what the Weather IPT is prepared to offer them in reducing weather impacts on NGATS. The Weather IPT is cognizant of the fact that the provision of weather information is not am NGATS goal in itself, but rather it is a service component of NGATS whose purpose is to support higher goals—the goals whose attainment are hampered by weather. In this context, the NNEW IOC Definition is expected to evolve based on the remaining IPTs developing a deeper understanding of how weather may be best integrated into their decision processes. It is written prior to the customer IPTs articulating their needs so as to serve as a starting point, and an indication to them of what will be possible. While it provides a measure of success for the Weather IPT, changes should be anticipated in response to user needs. The capabilities provided at IOC are a selected subset of the ultimate NGATS weather vision.