# Climate Perspectives in the Intra-Americas Seas
## 3 Regional Climate Features
### Rainfall
#### 3.4.2 Tropical Cyclones  
Tropical cyclones (TCs) represent an economic and societal threat for the western North Atlantic basin, including the US Atlantic Coast, coastal Mexico, Central America, and the Caribbean [134]. Even when storm surges account for the largest number of casualties, many of the highest fatality events in the Atlantic basin are rain-induced disasters on steep terrains in the Caribbean and Central America linked with landslides. The indirect effect dominates the impact of TCs in Central America [135]. However, direct impacts also occur when the TC landfall is located in the isthmus. Although the landing of TCs in Central America is infrequent, TCs have been recorded to affect Central America with landfalls as southern as Nicaragua and Costa Rica [136; 137; 138; 139]. The tropical North Atlantic (TNA) and the eastern North Pacific (ENP) are regions of high tropical cyclogenesis. TCs generally develop over oceans with SST \(>\) 26 \({}^{\circ}\)C, from pre-existing atmospheric disturbances, and often move out of these regions into higher latitudes. TC genesis may be a result of nearly classic baroclinic development [140], the interaction of EWs or other low-level disturbances with tropical upper tropospheric disturbances [141; 142; 143].  
The annual distribution of TCs is shown in Figure 5 for the Atlantic (A) and eastern tropical Pacific (B), from which the interannual variability of the TC intensity has been highlighted. For the TNA basin, the main development region is defined as the TNA south of 21\({}^{\circ}\) N and the Caribbean Sea. In this area, cyclonic activity mainly originates from the African easterly waves (AEWs) that propagate from West Africa towards the TNA. Winds in the mid and upper atmosphere may steer up cyclones to the north, when TCs reach latitudes near 30\({}^{\circ}\) N, they often move northeast. On average, AEWs account for nearly 60% of the Atlantic basin tropical storms and non-major hurricanes, and nearly 85% of hurricanes of strong intensity [144; 145]. The Caribbean islands, the Caribbean coast of Central America, and the Yucatan Peninsula experience the direct influence of TCs, particularly, the most severe systems as they move along the storm track. These systems form at a low latitude, east of 100\({}^{\circ}\) W, and travel slowly westward, where they reach their highest intensity. While the origins of ENP tropical waves continue to be debated, they are thought to originate from reinvigorated AEWs that have propagated over the Central American isthmus [97; 146]. On average, the eastern Pacific hurricane season extends from May to November, commencing earlier than the Atlantic basin and experiencing the maximum amount of activity near 17\({}^{\circ}\) N, 108\({}^{\circ}\) W (southwest of Manzanillo, Mexico). Of the TCs recorded over the ENP tropical cyclone basin between 1949 and 2006, roughly 20% are estimated to have caused tropical storm force winds along the Mexican coastline. TCs affecting land areas other than Mexico in the ENP are rare. There are only four TCs that have affected areas of the Central American Pacific coast based on the historical records.