African easterly waves (AEWs) are known precursors to tropical cyclone (TC) formation, although it is not always clear which AEWs will develop and which AEWs will not. To investigate AEW evolution, this study examines novel observations from the geostationary Advanced Baseline Imager (ABI) during July-September 2019. Case studies are conducted for two AEWs: one that became Hurricane Dorian, the strongest and most devastating hurricane of the 2019 Atlantic hurricane season, and a long-lived September AEW that did not become a TC. Lower-level moisture and flow, and the strength and spatial distribution of convective activity, differed between these two waves. By then exploring these characteristics for additional developing and non-developing AEWs, ABI observations show that developing AEWs are associated with low-level moist air ahead of the wave combined with enhanced convective activity, while non-developing AEWs tend to encounter drier air and exhibit a persistently broader structure with less-organized convection.

Located in the subtropical central-eastern Bahamas, San Salvador Island is impacted by both synoptic-scale weather systems as well as local features and the North Atlantic Subtropical High. This study explores rainfall variability via one year of daily rain gauge observations in relation to daily weather patterns identified from 18 UTC surface analyses. Satellite-derived rainfall estimates are then compared to gauge observations to look at days when gauge data was missing. Though non-synoptic classifications comprised 61.1% of the days and synoptic classifications comprised 38.9% of the days, more rainfall was produced by synoptic days. Unlike other studies done on San Salvador, this study uses multiple observations—in situ, surface analyses, and satellite—to further our understanding of San Salvador’s rainfall. This study also establishes methods to explore synoptic and non-synoptic impacts on the island’s rainfall using additional years as more rain gauge data become available.