Tools for Graphical Interaction (GI) are being implemented in the forecaster's workstation, METLAB, developed by 3SI for the Dutch NMC KNMI. During 2000, KNMI implemented the first phase of the GI project by integrating the On-Screen Field Modification (OSFM), a model modification tool developed by the UK MetOffice, with the forecaster's workstation. This technique, first presented as part of Metlab at the 17th IIPS conference, provides forecasters the capability to apply position and strength changes to synoptic-scale features -- where the modification at one atmospheric level (e.g., surface) is then computed and all levels throughout the troposphere are modified consistently.

During the second phase of the GI project, tools for small-scale interaction have been implemented. These tools are based on new and existing concepts, such as object-based modification areas, structure functions, time evolution (also known as "tweening"), the merging of different models, model field calculator, and others. These new GI techniques will enable the forecaster to efficiently modify short-range NWP model output based on data from other sources.

The ultimate goal of the complete GI project is to provide the forecaster with tools to apply both synoptic and small-scale modifications to models, which may be merged, in order to derive a final model solution. A central forecast database is being developed concurrently with this project to manage the original and forecaster-modified model data, thus ensuring a coherent and consistent dataset for the generation of forecast end products.

The GI concepts for small-scale interaction will be presented both from a functional and technical point of view. Also some operational experiences and a short demonstration showing the total GI project will be presented.