The Development of Global Ensemble Forecast System (GEFS)

NCEP Global Ensemble Forecast System (GEFS) is currently running at T254L42 (approximately 55km horizontal resolution) for 0-196 hours forecast, T190L42 (approximately 73km horizontal resolution) for 196-384 hours forecast with GFS v9.0. This system was implemented in NCEP operation since February 10, 2012. In year 2014, NCEP GEFS will pan to have major upgrades which include several significant changes, such as 1). GFS Semi-Lagrangian version with many upgrades of model physics (version 10.0); 2). Resolutions will be T574 (T384 for physics – 34km) with 64 hybrid levels for all 16-day forecasts; 3). Ensemble initial perturbations will be improved by using EnKF analysis/forecast with Ensemble Transform and Rescaling (ETR); 4). Stochastic Total Tendency Perturbation (STTP) will be adjusted for better performance of higher resolution GFS Semi-Lagrangian model and physics. Based on part of above upgrades, a period of Sandy case has been tested. A preliminary result indicates the new model with proposed configuration of GEFS will improve Hurricane Sandy's forecast (track) about 6-12 hours in advances to current operation GEFS to predict storm toward northwest and landing. The retrospective experiments will be run and evaluated during next few months. The results will be presented to the conference.