Seasonal prediction is one important element in a seamless prediction
chain between weather forecast and climate projections. After several
years of common development in collaboration with Universität Hamburg
and Max Planck Institute for Meteorology, the Deutscher Wetterdienst
performs operational seasonal forecasts since 2016 with the German
Climate Forecast System, now in Version 2 (GCFS2.0). Here, the
configuration of previous system GCFS1.0 and the current GCFS2.0 are
described and the performance of the two systems is compared over the
common hindcast period of 1990-2014. In GCFS2.0, the forecast skill is
improved compared to GCFS1.0 during boreal winter, especially for the
Northern Hemisphere where the Pearson correlation has doubled for the
North Atlantic Oscillation index. During boreal summer, overall a
similar performance of GCFS2.0 in comparison to GCFS1.0 is assessed.
Future developments for climate forecasts need a stronger focus on the
performance of seasonal dependent processes in a model system.