Unprecedented suppression of local upwelling in the Gulf of Panama predicted a season in advance

Wind-driven upwelling of subsurface ocean waters to the surface is a fundamental component of ocean dynamics, and ensures nutrient-rich waters reach the epipelagic zone. Weakening or collapse of upwelling can reduce nutrient availability, potentially impacting ecosystem health and fishing activities. In early 2025, the Gulf of Panama experienced an unprecedented collapse of the local upwelling system, indicated by exceptionally weak northerly winds leading to record warm ocean temperatures and reduced nutrient availability. Despite the societal relevance of this local-scale process, the predictability of upwelling strength and in particular collapse, remains poorly understood. 

Here, we explore the predictability of upwelling in the Gulf of Panama on seasonal timescales, and find that the unprecedented collapse of 2025 was accurately predicted a season in advance. We employ the operational seasonal forecasting system CMCC-SPS4 which has a horizontal resolution of 0.25o for the ocean component, 75 vertical depth levels, and outputs 40 ensemble members. Forecasts of sea surface temperatures initialised in November and December of 2024 predicted record values for January to March 2025, indicating considerable weakening of upwelling. Validation against the OSTIA sea surface temperature dataset using hindcasts from 1993 to 2024 demonstrates high probabilistic and deterministic skill, including for predictions of upper-quintile temperature events. Moreover, by validating against the global 1/12o GLORYS12 ocean reanalysis, we also find an increase in temperature forecast skill with depth, making the case for exploiting subsurface information for improved early-warning. 

While high surface temperatures are often used as an indicator of upwelling collapse, we show that in 1998—despite strong winds and active upwelling—extreme temperatures occurred throughout the water column. These results suggest that surface temperature records alone may not fully capture changes in nutrient availability. To ensure that the forecast system captures the collapse of upwelling, we also explore the predictions of regional winds and derived upwelling indicators. 

This study demonstrates the utility of seasonal forecasting in local marine environments and makes the case for future uptake in activities related to the Blue Economy. The work also supports the definition of user-relevant indicators of extreme temperatures (Horizon Europe project “ObsSea4Clim”) and the role of reanalyses in studying subsurface temperature extremes (as part of the ocean reanalysis validation project “GLORAN”).