By investigating the relationship between tropical cyclogenesis (TCG) over the South China Sea (SCS) and the intraseasonal oscillation (ISO), we found that the number of TCG varies significantly with the life cycle of 10–30-day/30–60-day mode of the ISO (QBWO/MJO). Considering the linkages between them, an extended-range forecast method for TCG over the SCS was constructed based on the spatial temporal projection model (STPM). By determining the phases of the QBWO and MJO from STPM, daily genesis rate (DGR) sequences at 10-day and 20-day lead time were derived. When the DGR sequence is in its positive phase, we consider that there is a high possibility of TCG over the SCS. Hindcasts for TCG in 2009–2018 indicate that the extended-range forecast method can successfully capture TCG over the SCS. For the 10-day lead time, the hitting rate is 80%, the missing rate is 20% and the false alarming rate is 32.4%, whereas with the increasing lead time, the hitting rate decreased to 74.3% and the false alarming rate increased to 35.3% at the lead time of 20 days.

通过调查南海（SCS）热带气旋（TCG）与季节内振荡（ISO）之间的关系，我们发现TCG的数量随着10-30天/30-60-天的生命周期变化显着。 ISO (QBWO/MJO) 的日间模式。考虑到它们之间的联系，基于时空投影模型（STPM）构建了一种TCG在SCS上的扩展范围预测方法。通过从 STPM 确定 QBWO 和 MJO 的阶段，导出了 10 天和 20 天提前期的每日发生率 (DGR) 序列。当 DGR 序列处于正相位时，我们认为 TCG 超过 SCS 的可能性很高。2009-2018 年 TCG 的后报表明，扩展范围预测方法可以成功捕获 SCS 上的 TCG。10天的交货期，命中率为80%，