With Harvey and Irma ripping through the Atlantic Basin and causing untold amounts of damage, the storm watchers of the world now have their eyes on that part of the world. Many are asking questions like, how do these storms begin? And, are there any more monster storms coming? A peek at a place called the Cape Verde Islands and at how hurricanes form can give us a hint of what more may be coming.
Hurricanes can be devastating to any area that they hit. But, for some of the smaller, less developed islands in the Caribbean Sea, they can be overwhelming. As an example, the pictures coming from Saint Martin/Sint Maarten after Irma showed the destruction that storm wreaked. And that is only part of the story. The storm left many people homeless, and this at a time when another storm, Jose, may be on its way. And on the island of Barbuda where “90% of its buildings were destroyed,” according to Yahoo News, this is not good news.
Jose, like Irma, and possibly to a less degree Harvey before them, had its origins off the west coast of Africa, near a small chain of isles called the Cape Verde Islands. It’s not the islands themselves that cause the storms. It just happens that where these storms form, the Cape Verde Islands sit and that is where Cape Verde Hurricanes get their name. But the reason that the storms form in that area is actually more a function of the winds coming indirectly off of the dry Sahara Desert.
During the months of June through November especially, the climate differences between the hot, dry Sahara and the cooler, wetter area around the Gulf of Guinea will clash. This clashing causes easterly winds to be generated. These winds are called the African Easterly Jet. With the wind, thunderstorms often form when enough moisture is present. But, during this time of year, conditions called “tropical cyclones” can develop. According to the National Hurricane Center, a tropical cyclone is “a rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has a closed low-level circulation.”
These tropical cyclones, which rotate in a counterclockwise direction in the Northern Hemisphere, then move in a westward direction. As long as they stay at less than 30 degrees North latitude (approximately the southern coast and border of the continental U.S., excluding Florida), these storms tend to keep moving west. But when they move above this latitude, usually due to winds pushing them, the storms tend to start moving to the northeast.
Even if the African Easterly Jet winds don’t cause cyclonic activity in the Atlantic, they can impact weather activity and tropical cyclones in the Pacific. If the winds stay below 20 degrees North latitude, they can move across Central America and then cause storm activity to generate in the Pacific.
Keeping an eye on weather activity is important this time of year, especially with the number of storms that have already hit. Web apps like Ventusky, Windy, or WindGuru can help to see what may be coming. Weather and wind conditions can be projected several days out. What do they see? That Jose will probably not be the last storm coming off of the Cape Verde Islands this year. In fact, another storm looks to form by mid-week. Hopefully, if it does form, it gets to 30 degrees North latitude quickly, moves northeast out to sea, and stays away from civilization. Harvey, Irma and probably Jose will have done enough damage for one season.
[Featured Image by NOAA]