Weather types across the Caribbean basin and their relationship with rainfall and sea surface temperature (original) (raw)

and summertime WTs is rather abrupt, especially in May. One summertime WT (WT 4) is prevalent in summer, and almost exclusive around late July. It is characterized by strong NASH, fast Caribbean low level jet and rainfall mostly concentrated over the Caribbean Islands, the Florida Peninsula, the whole Central America and the tropical Eastern Pacific. The two remaining summertime WTs display widespread rainfall respectively from Central America to Bermuda (WT 5) and over the Eastern Caribbean (WT 6). Both WTs combine reduced regional scale subsidence and weaker Caribbean low-level jet relatively to WT 4. The relationships between WT frequency and El NiƱo Southern Oscillation (ENSO) events are broadly linear. Warm central and eastern ENSO events are associated with more WT 4 (less WT 5-6) during boreal summer and autumn (0) while this relationship is reversed during boreal summer (+1) for central events only. In boreal winter, the largest anomalies are observed for two WTs consistent with negative (WT 2) and positive (WT 8) phases of the North Atlantic Oscillation; more (less) WT 2 and less (more) WT 8 than usually occur from January to early April during warm (cold) ENSO events, the strongest anomalies being recorded during eastern events. Multinomial logistic regression is used to hindcast the 11-day low-pass filtered occurrence of WTs from local (Caribbean Sea and Gulf of Mexico) and remote (Eastern and Central Tropical Pacific) sea surface temperatures (SSTs). In boreal summer, the interannual variability of the seasonal occurrence of WTs 4-6 is well hindcast when at least the Caribbean Sea and Eastern Tropical Pacific are included as predictors with anomalously warm (cold) SSTs over the Caribbean Sea (Eastern Tropical Pacific) being related to more WT 5-6 and less WT 4 and vice-versa. Using antecedent SST to forecast WT frequency shows that the SST forcing is negligible at the start of boreal summer and increases toward its end.

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