This study investigates the potential of using Pacific subsurface ocean temperatures to predict South China tropical cyclone landfall up to a year in advance. A subsurface temperature index, subNiño4, is defined, and a predictive model based on subNiño4 anomalies demonstrates robust forecast skill (23% against climatology), comparable to existing forecasts issued much later in the spring. The subNiño4 index precedes surface El Niño/Southern Oscillation (ENSO) conditions by about 12 months, influencing atmospheric heating patterns and subsequently the steering of tropical cyclones towards South China landfall. The findings suggest that regional subsurface ocean temperature anomalies could significantly extend the lead time of atmospheric predictions in other regions.

Nathan Sparks, Ralf Toumi