Abstract
The Main Development Region (MDR) is the region of the North Atlantic Ocean bounded between 10-20° N and 20-60° W where about 79% of all major hurricanes develop from African Easterly Waves (AEW) (Van Den Dool et al., 2005). The amount of tropical cyclone (TC) activity that forms in the MDR strongly dictates the overall activity of the hurricane season. Robust correlations exist between large-scale drivers, such as the El Niño Southern Oscillation (ENSO) and Atlantic Meridional Mode (AMM), and the overall TC activity in the Atlantic, which exhibits interannual variability (Bell and Chelliah 2006). Although previous studies (Bove et al., 1998, Goldenberg et al., 2001, Landsea and Gray 1992) have linked these internal climate variabilities to TC occurrences within different subregions of the Tropical Atlantic, little is known about the response of these atmospheric drivers to the spatial distribution of TCs in the MDR. These TCs in particular are produced from AEWs during the climatological peak of hurricane season in August and September (Gray 1984). This results section of this study is split into two parts. The first part examines how a portion of the annual variability of TC genesis latitude can be possibly linked to large-scale oscillations such as ENSO and AMM. The second part of the analysis explores the variability of TC activity in the MDR also using the genesis latitude of TCs, but instead, systems are grouped by storm-centric characteristics such as landfall and Rapid Intensification (RI). Once TCs are grouped, comparisons between latitudinal clusterings of different groups can be drawn. Aside from substantial annual variability in the climatological dataset defined in this study from 1980 to 2021, there are overall weak signals from the large-scale oscillation's impact on the latitudinal variability of developing TCs. More significant trends were observed for the individual TC groupings. TCs that eventually strengthened into major hurricanes or rapidly intensified generally formed at lower latitudes within the MDR and within only a few degrees of latitude of each other. TCs that eventually made landfall in North America were also found to form south of 15° N with a rapid drop-off in landfalling cases that formed north of this line of latitude. These quantifiable relationships can assist forecasters in improving short and medium-range forecasting of TCs in the MDR.