With the exception of the national sector, the three sub-sectors will change as SPC forecasters monitor these areas for hazardous weather. This information is provided by SPC as a way of sharing the latest severe weather forecast techniques with local forecasters.

The SPC runs a 2-pass Barnes surface objective analysis around :05 after each hour, using the latest RUC forecast as a first guess. Next, the surface data is merged with the latest RUC forecast upper-air data to represent a 3-dimensional current objective analysis. Finally, each gridpoint is post-processed with a sounding analysis rountine called NSHARP to calculate many technical fields related to severe storm forecasting.