Historically variation among National Weather Service forecaster methodologies was not a mission-critical issue. This was largely due to the fact that the end product - a textual forecast product – was subjective in nature. The choice of conceptual model, or even the interpretation of the conceptual model (the translational process) was obscured by semantics (e.g., “occasional rain” v. “showers”, or “partly cloudy”).

However, within the IFPS/GFE system the methodology is a defining and essential characteristic. Forecast offices with mature GFE/IFPS implementations indicate that the approach one uses in GFE will make, or break the forecast process. Thus developing the correct approach is vital to the forecaster in the quest for an internally consistent suite of sensible weather element grids.

There are innumerable IFPS/GFE methodologies currently in vogue across the NWS: some systematic, and some not. The software design allows the forecaster to manipulate the grids in an infinite number of way. With an unlimited number of degrees of freedom, the forecaster is free to define a preferred mode of operation.

During the exploration and development phase this was a good thing. However, IFPS/GFE is now approaching “adulthood” (ORD/IOC), and the lack of a consistent methodology is becoming an impediment to the maturation of IFPS/GFE. It is suggested that a standard methodology should at minimum attempt to address at least three significant issues: the lack of a consistent approach to grid production; the number of independent grids required of the forecaster; and the physical inconsistencies among grids.