Evaluation of the MYNN PBL Scheme for Predicting Tropical Cyclones with HWRF Model

In the past two decades, there has been a steady decrease in tropical cyclone (TC) forecast errors. However, the decrease in intensity forecast errors was not as impressive, and more work is needed to meet the goals of the Hurricane Forecast Improvement Project (HFIP). The model physical parameterizations, and the interactions among different schemes, are critical to model performance. In recent years, the Developmental Testbed Center (DTC) ran experiments of HWRF with a variety of cumulus and microphysics schemes, but none outperformed the operational configuration. Recent studies done by DTC showed negative temperature and moisture bias in the PBL. The MYNN PBL was included in the HWRF model and showed promise with limited testing.

The DTC will test and evaluate HWRF with the MYNN PBL scheme and compare the results against a control using the operational GFS EDMF scheme with a larger sample. Assessments will be done through a combination of physical process diagnostics, as well as traditional track and intensity verification. Additionally, evaluation of large- and storm-scale fields will be explored to further investigate sensitivities to the MYNN scheme in HWRF.