An Evaluation of HWRF based Ensemble Prediction System for 2015 Atlantic Basin Real Time Parallel Experiment

The NOAA/NCEP/EMC operational HWRF based Ensemble Prediction System (HWRFEPS) has undergone constant improvements, and has been running real time parallel for storms at Atlantic basins for the last three years. The upgrades of HWRF-EPS included situation-appropriate perturbations to the initial-time position and intensity and stochastic perturbations on surface drag coefficient. In this study, the FY15 HWRFEPS upgrades will be reviewed and is performance will be verified against best track for 2015 Atlantic hurricane season in terms of both track and intensity forecasts. The results will be compared with its deterministic version and other top-flight regional ensemble systems. The evaluation will also include demonstration of the improvement of statistical features of the current HWRF EPS, such as track and intensity spread, over the previous version. A case study of hurricane Joaquin will be presented to compare track forecasts from HWRF –EPS and deterministic HWRF. Experiments are done by selecting best and worst ensemble member with different perturbation option to find out what is the main source of uncertainty that cause the divergence of the ensemble track forecasts.