. AQPI: RAP/HRRR Model Forecasts of Atmospheric River Events over the San Francisco Bay Area

Abstract
Atmospheric river events can cause flooding and deaths and are responsible for nearly half of California's annual precipitation. We evaluate multiple heavy rain events that have occurred over the past year by running retrospective simulations of the RAP/HRRR mesoscale weather model and compare quantitative precipitation forecast (QPF) and other model parameters to available observations. We evaluate multiple versions of the RAP/HRRR model (HRRR versions 2, 3, and 4) as well as simulations of HRRRv4 with and without X-band radar data included in the data assimilation. Model forecasts are compared to widely-used quantitative precipitation estimation (QPE) products such as the Stage IV analysis, rain gauges, and radars, as well as measurements of temperature and winds.