Global Interactive Forecast System
The original vision of the THORPEX programme envisaged the development of a more interactive approach to weather forecasting, designated the Global Interactive Forecast System, or GIFS. Conventionally, there was a linear progression with observations being made, then assimilated into an NWP model, a model prediction being run, output post-processed then the forecasts being delivered to users. GIFS envisaged a more interactive approach, in which forecasts could be run on-demand in response to user requirements, additional post-processing would be run for severe weather events, the model predictions would be based on ensembles (leading to probabilistic risk-based forecasts), and additional targeted observations would be made where they can improve the forecast skill. Some, but not all, of these approaches, have now been adopted for operational weather forecasting. For example, observation targeting has had limited success in improving forecasts of mid-latitude storms, but more success for tropical cyclones.
TIGGE has contributed to the development of the GIFS vision mainly through supporting the development of advanced probabilistic products to support forecasts of severe weather events, including tropical cyclones, heavy precipitation events and wind storms. A report outlining a long-term vision for GIFS is available via the GIFS-TIGGE working group web page. The page also includes a proposal for a forecast demonstration project (FDP) for GIFS, but it was decided that it was better to work in conjunction with other FDPs instead.
The first step in these developments was the exchange of ensemble tropical cyclone prediction data (using a new data format, CXML) which was initiated during T-PARC (the THORPEX Pacific Asian Regional Campaign) in 2008. These enabled the development ensemble-based products, such as strike probability maps showing the risks of a tropical cyclone passing close to any given location.
Another approach entails the exchange of gridded data to highlight areas of heavy rain, strong wind or extreme temperatures. The TIGGE Museum website shows examples of severe weather forecast products; they highlight areas in which the model predictions show a risk of events that are extreme compared with the model climatologies.
These types of products are now starting to be used to support operational weather forecasting. In particular, some of the products are now being made available for use in the WMO (SWFDP), including tropical cyclone strike probability maps and the gridded severe weather products for heavy rainfall and strong winds.