Designing Sub-Regional Anticipatory Action for Hurricanes in the Eastern Caribbean

Small Island Developing States (SIDS) in the Eastern Caribbean face escalating hurricane risk under climate change, with impacts driven by compound hazards including extreme wind, rainfall, and storm surge. Anticipatory Action (AA) mechanisms—where predefined actions are activated based on forecast thresholds—offer a means to translate advances in climate and weather prediction into timely, risk-reducing interventions. However, designing robust, decision-relevant trigger models that balance forecast skill, uncertainty, and operational feasibility remains a key challenge, particularly in multi-country contexts.

We studied the feasibility of a sub-regional Early Action Protocol (EAP) covering Saint Kitts and Nevis, Dominica, and Antigua and Barbuda, and focused specifically on how to design a sub-regional trigger model. Using stakeholder consultations, analysis of national disaster management systems, analysis of historical and synthetic events by modelling wind, surge, and rainfall, and review of existing forecasting products, we assessed trigger options across temporal scales, compound hazard components, and impact relevance.

Results show that the wind and track forecasts from the US National Hurricane Centre demonstrated substantial improvements in accuracy over recent decades. The NHC’s 48-hour track error now averages about 90 km, meaning that areas at risk can be identified with an acceptable uncertainty in terms of storm size and asymmetry. Early actions possible within this lead time can include mobilizing communities, cash distributions, and prepositioning stock. Also, the NHC forecast is the official source, widely adopted by the respective national agencies in the three countries. In the future, the trigger model could be improved by, for example, ECMWF’s AIFS, Google DeepMinds GraphCast, or Microsoft Research’s Aurora, as these have demonstrated the ability to deliver medium-range forecasts with skill comparable to or surpassing traditional numerical models. While these AI models are not yet operational tools at national centres, they are available for experimental use and could be incorporated through the Caribbean Institute for Meteorology and Hydrology (CIMH) as complementary resources for rapid local updates and scenario planning within a newly developed anticipatory framework. In that case, a layered trigger architecture could be designed, containing: (i) probabilistic tropical cyclone track and intensity forecasts; (ii) impact-oriented thresholds linked to rainfall accumulation, wind exposure, and storm surge; and (iii) contextual readiness criteria reflecting response capacities.

Our study highlights key design principles for anticipatory trigger models in SIDS now and in the future: transparency, simplicity, tolerance to forecast uncertainty, and alignment with decision timelines for early action. By articulating how forecast information can be operationalised across borders, this contribution advances the integration of climate services and anticipatory humanitarian action in highly exposed island regions. A sub-regional trigger model can leverage shared meteorological information and pooled technical expertise, while allowing country-specific activation thresholds to account for differing exposure and coping capacities. A future initiative will focus on scaling up to Barbados and Belize.