Convective Scale Forecast for Day Two from the High-Resolution Rapid Refresh

The High Resolution Rapid Refresh (HRRR) model is now being run operationally at the National Centers for Environmental Prediction (NCEP) in Silver Springs, Maryland. A more advanced version of the model is run hourly in real time at the Global Systems Division (GSD) of the Earth System Research Laboratory (ESRL) in Boulder, Colorado. A third version of the model has recently been set up on Peregrine, the supercomputer of the National Renewable Energy Laboratory (NREL) in Golden, Colorado. This third version is only run four times per day, but the forecast length is extended to 48 hours. In this talk, we provide an overview of the model performance for convective events in the day two period.

Initial conditions for the Peregrine HRRR are still obtained from the advanced version of the Rapid Refresh (RAP) run at ESRL GSD. Boundary conditions out to 48 hours are obtained from the operational Global Forecast System (GFS) model. The Peregrine HRRR uses the same version of Gridpoint Statistical Interpolation (GSI) and Weather Research and Forecasting (WRF) model as the advanced version run at ERSL GSD.

We demonstrate the value of these forecasts for evaluating the potential for severe weather during the second day, a task which is an important goal of the Storm Prediction Center (SPC). We show some objective verification, as well as some case studies from severe weather outbreaks during this past summer. Other applications of the two-day forecasts are briefly mentioned.