Data from: Impacts of Dropsonde Observations on Forecasts of Atmospheric Rivers and Associated Precipitation in the NCEP GFS and ECMWF IFS models

European Centre for Medium-Range Weather Forecasts (ECMWF) and National Centers for Environmental Prediction (NCEP) integrated vapor transport (IVT) and precipitation NetCDF data from control forecasts and data denial forecasts (without dropsondes assimilated) for Atmospheric River Reconnaissance (AR recon) 2019 and 2020. Forecast lead times are from 24 to 120 hours. NCEP files were created using the Global Forecast System (GFS) v15. ECMWF files were created using the Integrated Forecast System (IFS) cycles 45r1 and 46r1. Control (CTRL or buoy_CTRL) forecasts are the operational forecasts from each center. The denial (Deny) forecasts only differ from the control in that the dropsondes from AR recon (Atmospheric River Reconnaissance) were excluded from the assimilation. Precipitation is the 24-hour accumulation. IVT is computed from pressure level data, integrated from the surface to 300 hPa (for ECMWF) and from the surface to 200 hPa (for NCEP).