Abstract
Southwest cloud bands during spring (April and May) bring rains to central Caribbean islands at the end of the dry season. A cluster analysis of daily 500-hPa geopotential height fields for 1980–2021 identifies a low-west–high-east dipole pattern related to Pacific–North America response to El Niño–Southern Oscillation (ENSO) and springtime wet spells over the Dominican Republic and Puerto Rico. The regional dipole and local rain time series are ranked to identify the top 10 cases for analysis of meteorological conditions. Hovmöller plots of midlevel meridional wind and specific humidity during April 1983 and May 1986 wet spells reveal a standing Rossby wave train pattern that converges moisture onto the leading edge of a subtropical trough. Composite vertical sections during Caribbean Sea wet spells reveal lower easterly–upper westerly wind anomalies over South America associated with the equatorial Madden–Julian oscillation. Thunderstorm clusters within the southwesterly airflow induce multiday wet spells and flash floods. A second statistical method demonstrated how ENSO underpins Caribbean spring climate anomalies via tropical ocean–atmosphere Rossby wave coupling. Historical trends and long-range projections indicate that springtime tropical–midlatitude interactions may diminish due to an accelerating Hadley cell and retreating jet stream, leading to a delayed onset of the wet season across the Antilles Islands.
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