Understanding How Tropical Waves Lead to Named Features in the Atlantic

You may hear a lot of chatter in the coming weeks about tropical waves. What is this weather feature and how does it lead to tropical storms or hurricanes? We have all of the details for you here.

What is a Tropical Wave?

Tropical waves often form the backbone of hurricanes. However, not all tropical waves go on to form named features, nor do all tropical weather events start as waves. Meteorologists define tropical waves as clusters of rain showers and thunderstorms that come to life during the Atlantic hurricane season.

These areas of low pressure push off the western coastline of Africa and into the Atlantic. The waves form when dry air masses from the north merge with the moist and cooler air that circulates over the jungles in the central portions of Africa. The clash of these two competing weather systems creates a jet stream of powerful winds over the large continent.

The waves then eject off the coast of Africa and head toward the Cabo Verde Islands. During the tropical weather season that runs from May to November, the waves move into the Atlantic every few days. The train of tropical waves reaches its peak activity stage in September.

Roughly 60 tropical waves move across the Atlantic basin during a typical hurricane season. Although not all of these waves turn into a meaningful threat, it just takes one wave to intensify and cause catastrophic damage.

Experts estimate that about 80% of all major hurricanes in the Atlantic Ocean get their start as tropical waves. It takes time for the wave to take on tropical characteristics and to reach the U.S. For instance, it can take up to two weeks for a new wave to travel from Africa and across the Atlantic to the coastline of North America.

With so many potential tracks that a wave can take on its journey, there is a wide range of landfall possibilities. This is where the National Hurricane Center (NHC) and its forecasting tools come in to help predict potential paths.

Many of the longest-lived tropical weather makers begin as tropical waves that form in Africa. These waves are able to strengthen as they churn over the warm ocean waters of the Atlantic this time of the year.

As noted earlier, some of these waves and the resulting tropical features never make a direct landfall. This happened in 2019 when Hurricane Lorenzo roared through the Atlantic as a major hurricane for three days, peaking at a Category 5 monster. Although Lorenzo never made a direct strike, its outer bands impacted portions of the British Isles and western Europe over its long life span.