A record-breaking rainstorm strike North China from July 29 to August 1, 2023, causing sudden regional floods and significant infrastructure damage. Accurate long-lead-time forecast and warning of this extreme event are crucial for damage reduction and water management. This study reveals the dominant circulations and the subseasonal potential predictability of this extreme precipitation event and discusses the possible advantages of using the dynamical downscaling method in extreme event prediction. The event was jointly influenced by easterly and southeasterly moisture transport from Typhoons Khanun and Dosuri and the north-westward extension of the western Pacific subtropical high (WPSH), forming a positive phase of the East Asia-Pacific teleconnection (EAP). When the warm and humid air encounters the Taihang and Yanshan mountains,  orographic lifting leads to strong moisture convergence and ascending movement, which is further intensified by upper-level divergence associated with the weakened upper tropospheric westerly jet. The global S2S models from the European Centre for Medium-Range Weather Forecasts (ECMWF) and China Meteorological Administration (CMA) showed skill in forecasting this extreme event about 1–2 weeks in advance, with the EAP is revealed as the main predictability source at subseasonal timescale. Specifically, the Climate-Weather Research and Forecasting (CWRF) regional model, developed based on CMA’s global S2S model, demonstrated improved predictive skill and stability for this rainstorm at longer lead time. This is mainly due to its better representation of key circulation evolution and the topographic influences on water vapor lifting, indicating the potential benefits of using dynamical downscaling model in extreme event prediction. The results provide scientific support for developing effective methods of extreme precipitation event predictions and shed light on further improving the S2S predictions.

extreme precipitation, S2S models, topography, typhoons, dynamic downscaling