Multi-Year High-Resolution Rapid Refresh Forecast Climatology

The High-Resolution Rapid Refresh (HRRR) model is run hourly in real-time at the Global Systems Division (GSD) of the Earth System Research Laboratory (ESRL). The model is run out to fifteen forecast hours over a domain covering the entire conterminous United States (CONUS) at a spatial resolution of three kilometers, allowing the use of explicit convection. Initial and boundary conditions are obtained from the operational Rapid Refresh (RAP), and three-dimensional variational data assimilation including radar reflectivity observations was implemented in April 2013 within the 3-km HRRR.

The high resolution of the HRRR model allows small-scale terrain and complex coastal features to be resolved, therefore permitting successful forecasts of localized orographic and coastal weather phenomena. The high resolution also permits an accurate depiction of convective-scale structures. Since the model is executed hourly, we can leverage a multi-year dataset from 2012-2013 to construct a climatology of HRRR forecasts that can be stratified into diurnal, lead-time, seasonal and regional composites.

We will present the methodology and some preliminary results of this ongoing work including summaries of the model atmosphere during 2012-13, with a focus on sensible weather elements including precipitation, cloud cover, and low-level wind speeds. HRRR forecasted precipitation totals will be compared with estimated totals from the Stage IV quantitative precipitation estimation product and model forecasts of composite radar reflectivity will be compared against composite radar reflectivity observations over the CONUS to evaluate diurnal, seasonal and regional model forecast biases and highlight the value of these composites in observation sparse regions.