Environmental Patterns Associated with Active and Inactive Caribbean Hurricane Seasons

This study of hurricanes passing through the Caribbean in the 1950–2005 period reveals that seasons with more intense hurricanes occur with the onset of Pacific La Niña events and when Atlantic SSTs west of Africa are above normal. Composites of NCEP reanalysis fields with regard to Caribbean hurricanes reveal development of an anomalous equatorial Atlantic zonal overturning circulation (upper easterly/lower westerly) that shifts toward the Caribbean coincident with a westward spread of the cold tongue in the east Pacific. Ocean–atmosphere coupling is promoted through interaction of the southern Hadley cell and the Atlantic ITCZ. A heat budget analysis suggests that evaporation governs SSTs in the major development region (MDR) and near Venezuela, but the signal is weak prior to May. Using the knowledge gained, statistical algorithms are developed to predict Caribbean hurricanes at seasonal lead times. These make use of equatorial Pacific SST, subtropical Atlantic SST, and the zonal Walker cell over the Atlantic.