Status and perspectives of SINFONY – the seamless combination of Nowcasting and NWP at DWD

DWD's new Seamless Integrated Forecasting system (SINFONY) is entering a new phase.

Up to now the focus was initial development until "fitness for operations" in a project framework, to improve very-short-range forecasting of intense convective events from observation time up to 12h, with weather radar at the heart of it. Having DWD's warning process (forecasters, automated systems) as well as German flood forecasting authorities in mind, seamless ensemble products in observation space (radar reflectivity composites, precipitation fields and convective cell objects) were developed, as well as informations on the probability  of hazards like heavy precipitation, hail, wind gusts and lightning.

In the last eight years we developed

1) Radar Nowcasting ensembles for areal precipitation, reflectivity (STEPS-DWD) and convective cell objects including hail and life cycle information (KONRAD3D-EPS) with good forecast quality up to 1-2 hours.

2) A new regional NWP ICON-ensemble model (ICON-RUC-EPS) with LETKF assimilation of 3D radar volumes, cell objects, Meteosat VIS and IR channels and hourly new forecasts on the km-scale, whose forecast quality exceeds Nowcasting after about 1h. Advanced model physics (2-moment microphysics with prognostic hail) lead to an improved forecast of convective clouds and to more consistent model equivalents for radar data and visible/infrared satellite data based on detailed forward operators (EMVORADO and RTTOV-MFASIS).

3) An optimal combinations ("blending") of Nowcasting and NWP ensemble forecasts in observation space, which constitute the seamless forecasts of the SINFONY. Gridded combined precipitation and reflectivity ensembles (INTENSE) are targeted towards hydrologic warnings. Combined Nowcasting- and NWP cell object ensembles (KONRAD3D-SINFONY) help evolve DWD’s warning process for convective hazards towards flexible “warn-on-objects". Reflectivity composites and 3D cell objects are computed with the same software as for observations and Nowcasting.

4) Common Nowcasting and NWP verification systems for precipitation, reflectivity and cell objects help to continuously improve the SINFONY components.

Now we will expand in two directions.

On the one hand, the existing prototypes will be installed and maintained operationally as a cross-cutting activity on a long-term basis. We already got the ICON-RUC-EPS into operations in July 2024.

On the other hand we will further improve the systems in a new project phase 2025-2028 towards seamless forecasts for other parameters/phenomena and other user groups:

• Temperature, wind, cloudiness, fog, solar radiation, visibility, ceiling for
• aeronautical forecasts, renewables, customer data portals,
• with good year-round performance,
• and seamless forecasts beyond 12h.

For this, we try to improve the ICON-RUC forecasts for these parameters, we blend ICON-RUC into ICON-D2 and we integrate satellite data into our Nowcasting and combined products.