To create its weather forecast DreiTageWetter uses the American numerical weather prediction (NWP) model WRF (Weather Research and Forecasting Model). There are different versions of this weather model. DreiTageWetter solely uses the WRF-ARW. Our current version is WRF-ARW V220.127.116.11. It is the last development stage of version 3.
We obtain the initial and boundary conditions for our weather simulations from the coarser American global numerical weather prediction (NWP) system GFS (Global Forecast System). The GFS dataset also takes observational, satellite and measurement data into account. Please read the developers' home page for a deeper understanding and further information.
Our model domain dimensions are 2800 km in north-south direction and 2800 km in east-west direction. The model domain includes a bigger part of Europe with Germany in the mid-region. The horizontal spatial resolution of our model is about 10 km.
The focus of our simulations is weather prediction for Germany. Hence you can select a weather report for a wide range of German locations, we use a database of the Federal Agency for Cartography and Geodesy. Since our model provides weather information clearly beyond the German national border (see above), we supply holiday weather for selected places in European regions. Accordingly our weather maps show the meteorological situation for a large part of Europe, too. Our weather maps are built with the visualization software GrADS.
We execute simulations two times a day that start as soon as the data from the GFS is available. The first simulation happens in the evening of the day before, so that the forecast data for today and the following three days is available at midnight. The second simulation operates in the night. It is an update and replaces the first simulation data at about 08:00 CE(S)T (Central European (Summer) Time). This proceeding is repeated every day once more. One simulation takes about 6 hours computation time. We calculate the simulations on an own computer system. A usable and up-to-date weather simulation requires much computational power. Hence we use many processors in parallel for one forecast, to bring the enormous calculations to completion in a practicable time frame.
For further information contact us or visit the developers' home pages of WRF-ARW and GFS, respectively.