Hourly assimilation of different sources of observations including satellite radiances in a mesoscale convective system case during RELAMPAGO campaign

•The impact of different observation platforms in a regional scale data assimilation is investigated over South America.•Assimilating frequent surface temperature and moisture observations improves precipitation forecasts associated with a huge mesoscale convective system.•Clear sky radiances improve the first-guess hourly accumulated precipitation but lead to neutral impacts in short-range precipitation ensemble forecasts.