Gridded MOS--Techniques, Status, and Plans

Point MOS forecasts have been provided to forecasters in the National Weather Service (NWS) and to other users for over three decades. The points are observation locations with a long enough record with which to produce robust statistical relationships with variables from Numerical Weather Prediction (NWP) models. Such point forecasts generally satisfied the need for postprocessing of NWP output, although there were numerous requests for forecasts for other specific points. With the advent of the National Digital Forecast Database (NDFD) and the methods for producing the grids in it (IFPS--Interactive Forecast Preparation System), it became imperative that interpretative guidance be provided on a grid, the same grid used at the NWS Weather Forecast Offices (WFO) for producing the official grids in the NDFD.

The Meteorological Development Laboratory is producing such guidance for some of the variables needed. This paper describes the current status and future plans of gridded MOS, and specifically concentrates on the techniques for producing it. The techniques include use of diverse data sets, regression analysis, objective analysis of point forecasts, and verification.