Progressive Enhancement in the Prediction of Subseasonal Tropical Convection in NOAA Dynamical Forecast Systems

This study evaluates subseasonal tropical convection prediction in NOAA's Global Ensemble Forecast System version 13 (GEFSv13) ensemble prototypes by comparing their performance with the operational GEFSv12 and the Climate Forecast System version 2 (CFSv2). The analysis focuses on the DYNAmics of the Madden‐Julian Oscillation (DYNAMO) period and examines both the overall improvement in GEFSv13 and the relative roles of upgraded model physics and enhanced initial conditions. Additional experiments using the GEFSv13 configuration were conducted to isolate these contributions. Results show that GEFSv13 prototypes substantially outperform GEFSv12 and CFSv2, with most gains arising from refined model physics and smaller, but still meaningful, benefits from initialization upgrades.