Cape Verde hurricane

Cape Verde hurricane. A Cape Verde hurricane is a tropical cyclone that develops into a tropical storm or hurricane in the deep tropical Atlantic Ocean, near or to the east of the Cape Verde islands. These systems originate from potent tropical waves that move off the coast of West Africa and traverse a long stretch of warm ocean waters, which often allows them to become intense and long-lived. Due to their formation region and trajectory, they pose a significant threat to the Caribbean, the Gulf of Mexico, and the East Coast of the United States.

Definition and characteristics

A Cape Verde hurricane is specifically defined by its genesis location, typically forming within the area from the coast of Senegal and The Gambia eastward to the Cape Verde archipelago. The key characteristic of these storms is their lengthy developmental track over the open Atlantic Ocean, where sea surface temperatures are consistently warm and wind shear is often low. This environment provides ample opportunity for organization and intensification, frequently resulting in major hurricanes of Category 3 or higher intensity. Their paths are generally westward, guided by the subtropical ridge, before potentially recurring northward under the influence of mid-latitude troughs.

Formation and development

Formation begins with a strong tropical wave, also known as an easterly wave, emerging from the African continent, often over nations like Mauritania or Senegal. As these disturbances move over the warm waters of the eastern Atlantic, they encounter the Intertropical Convergence Zone and favorable upper-level outflow patterns. The transition from a disorganized wave to a tropical depression requires sufficient Coriolis force, which is present even at low latitudes, and sustained convection around a developing low-pressure area. Subsequent development into a tropical storm and then a hurricane is fueled by latent heat release from the ocean, a process studied by agencies like the National Hurricane Center and NOAA.

Notable examples

Historical seasons have featured many devastating Cape Verde hurricanes. The 1935 Labor Day hurricane, which struck the Florida Keys, and the 1928 Okeechobee hurricane, which caused catastrophic flooding in Lake Okeechobee, are classic early examples. In the modern era, Hurricane Hugo in 1989 devastated South Carolina, while Hurricane Andrew in 1992 caused unprecedented damage in Florida and Louisiana. The extremely active 2005 Atlantic hurricane season included several, most notably Hurricane Katrina, which made landfall in Louisiana, and Hurricane Wilma, which set records for intensity in the Caribbean Sea. More recently, Hurricane Irma in 2017 ravaged the Leeward Islands and Florida.

Climatology and frequency

The climatological peak for Cape Verde hurricane activity aligns with the height of the Atlantic hurricane season, from mid-August through late September. During this period, sea surface temperatures in the Main Development Region of the Atlantic are at their maximum, and Saharan Air Layer outbreaks, which can inhibit development, are less frequent. Their frequency varies annually with larger climate patterns; for instance, they are more common during the active phase of the Atlantic multidecadal oscillation and during La Niña events, which reduce disruptive wind shear over the Atlantic. Historical analysis by the National Oceanic and Atmospheric Administration shows significant interannual and decadal variability in their numbers.

Forecasting and impacts

Forecasting the development and track of these hurricanes is a primary focus for the National Hurricane Center and other global forecast centers like the Met Office. Long-range prediction relies on monitoring Madden–Julian oscillation phases, sea surface temperature anomalies, and global model ensembles. Due to their long oceanic tracks, they often allow for extended warning times for land areas in the Antilles or the United States. However, their potential for rapid intensification, as seen with storms like Hurricane Maria, poses a major forecast challenge. The primary impacts stem from extreme storm surge, as with Hurricane Sandy, catastrophic wind damage, and prolific rainfall leading to inland flooding across regions like Central America and the Southeastern United States.