Status of Satellite Data Assimilation in the NSSL Experimental Warn-on-Forecast System

The goal of the Warn-on-Forecast (WoF) project is to provide probabilistic short-term (0-3 h) forecast guidance for high impact weather events such as tornadoes, hail, high winds, and flash flooding. A prototype system known as the NSSL Experimental Warn-on-Forecast System for ensembles (NEWS-e) has been developed to test a rapidly updating, ensemble-based data assimilation and forecasting system in a real-time environment beginning in 2016. This system assimilates a multitude of data types including conventional data from surface observations (parameters are temperature, dewpoint, wind velocity and pressure); WSR-88D reflectivity from the NSSL- Multi Radar Multi Sensor (MRMS) product, Level 2 Doppler radial velocity from radar sites within the storm-scale domain, and finally several forms of satellite observations.

Assimilating satellite observations such as cloud water path and clear-sky water vapor channel radiances have increased forecast skill compared to not assimilating satellite data in this system. Beginning in 2018, operational data from the first next generation geostationary operational environmental satellite (GOES-16) has increased the spatial and temporal resolution of satellite observations available for data assimilation. The 2018 version of NEWS-e assimilates GOES-16 cloud water path retrievals and recently clear-sky water vapor channel radiances. The assimilation of GOES-16 radiances is quite new and impacts are described. The primary goal being to improve the mid-tropospheric moisture environment within the model, allowing for better high impact weather forecasts. Finally, it is planned that GOES-16 derived atmospheric motion vectors (AMVs) will be assimilated into the 2019 version of NEWS-e. These data can supplement radial velocity observations in radar coverage gaps and add upper-level wind information where sounding and aircraft data are not assimilated.