Operational Hydrometeorological Predictions in Mountain Watersheds using the New National Water Model Implementation of the WRF-Hydro Modeling System

A new National Water Model (NWM) for the U.S. is being implemented for operational high-resolution water forecasting purposes by the NOAA National Water Center in partnership with other agencies and academic institutions. The initial implementation of the NWM is built upon the community WRF-Hydro modeling system and will begin operations during the summer of 2016. In this presentation, results from initial retrospective simulations and hindcasts of mountain snowpack and streamflow are shown. Regionally-synthesized verification statistics from mountainous areas using station observations of snowpack and streamflow along with gridded and basin-averaged comparisons of snowpack are analyzed in the context of understanding model sensitivity of model skill to different operational precipitation forcing datasets and selected model parameters. Model sensitivity to the quality of operational quantitative precipitation forcings from national radar mosaic products and high resolution numerical weather prediction models tends to dominate over hydrologic model parameter sensitivities. Findings from a regional season long field experiment in southern Colorado using novel precipitation and snowpack observations are also presented to provide a more mechanistic diagnosis of model performance. In general, findings from these preliminary assessments of the NWM suggest that overall fidelity in snowpack and streamflow analyses and predictions are significantly constrained by the quality of the meteorological forcings and that there is a need to improve these forcings in mountainous areas of the U.S.