Toward the development of prediction models for the primary Caribbean dry season

Abstract

Two statistical models are created for the Caribbean during its dry season. Canonical correlation analysis (CCA) confirms that there is a robust El Nino Southern Oscillation (ENSO) signal in the region during the dry season and that the mode manifests itself as oppositely signed precipitation anomalies over the north and south Caribbean. The south-eastern Caribbean becomes dry in response to a warm event. The first statistical model consequently uses a rainfall index averaged over the south-eastern Caribbean as the predictand. A model which retains an ENSO proxy as one of two predictors shows reasonable skill with hindcast predictions for the region. A second model is created using a Jamaican rainfall index as predictand. Jamaica falls in the transition zone i.e. between the oppositely signed north-south precipitation anomalies characteristic of the ENSO dry season mode. In this case no ENSO related predictor is retained in the final model. Composite analysis of select atmospheric variables for anomalously high and low rainfall years (for the dry season) give an understanding of the dynamics of the Caribbean dry season during phases of the ENSO, particularly those which lead to the creation of the transition zone.