What Are Cape Verde Hurricanes?

Andrew Was Here - By National Hurricane Center [Public domain], via Wikimedia Commons

A Cape Verde Hurricane is one that began life as a patch of disturbed weather over the Saharan Desert, then moved off the west coast of Africa, becoming a tropical wave.  As a wave  moves through or near the Cape Verde Islands, it may develop  into tropical cyclone.   When it does so while still within about 600 miles or the islands, it will be known as a Cape Verde system.

Many don't survive the long trek across the Atlantic, but some do.  Those that do can end up being very large and / or intense storms.  

Some have made history for themselves, and have etched themselves into our collective memories, like Hurricane Andrew, and that deadly and devastating one that struck Galveston in 1900.

Here is a selection of a few basics about these types of tropical systems - a simplified sampler, if you will. 

Image:  Hurricane Andrew making landfall in South Florida  (modifications mine)

When is the Cape Verde Season?

There are no exact dates, like with the official hurricane season, which begins on June 1 and ends on Nov 30. There is, however, a general time frame for when these types of storms are most likely to form. Not surprisingly, it at least partially coincides with the times when the tropics tend to be most active.

 We refer to that active period as the peak season. While there is no year to year guarantee, this usually is from about the first or second week of August, through about the end of October. There is, however, a general time frame for when these types of storms are most likely to form. Not surprisingly, it at least partially coincides with the times when the tropics tend to be most active.

Many years, the Cape Verde season ushers in the beginning of peak season, with waves coming off the African coast. The time frame for this activity is typically from about late July through sometime in September.

Note, however, that these dates are not absolute. That is, in all three cases - activity can occur before the normal starting date, and after the usual ending time.

Image source: my own compilation of two public domain open clip art images, with modifications. 

The Republic of Cape Verde is about 350 miles off the western coast of North Africa.  About half a million people live in the country, consisting of 10 islands, nine of which are inhabited.  There are also eight islets in the archipelago.

Hammered?  Not usually. These islands have a mild climate.  While the country rarely gets a full blown hurricane, they can get some heavy rainfall from tropical waves or depressions that may eventually become named storms or hurricanes as they cross the Atlantic Ocean.  Intensification normally doesn't happen to any great degree while the system is still in the vicinity of the Cape Verdes.

Image source:

By Waldir [CC-BY-SA-3.0, via Wikimedia Commons

Hurricane Dean, in 2007, was that year's strongest storm.  He began as a wave that came out of Africa on August 11.  Within two days, he had passed the islands, and become Tropical Depression Number Four.

Six days later, he had managed to cross the ocean and become a hurricane. In the process of transitioning from the Atlantic to the Caribbean, he intensified further. and quickly became a Major (Category Three) Hurricane.

After visiting the Major Antilles as a Category 4 storm, he assaulted the Yucatan with Cat 5 winds of 165 mph, gusting to 200.  He inflicted great damage, and virtually destroyed the little coastal fishing village of Majahual.  The massive (and very sturdy) concrete cruise ship piers at Costa Maya were ripped up.

Miraculously, there were no fatalities in Majahual.  Sadly, that was not the case everywhere.  Dean was a killer, leaving 45 people dead from St. Lucia to Mexico
, and causing over 1.6 billion dollars in damage.

Two other systems that originated from African Waves that year were  Hurricane Karen, and Tropical Storm Melissa.  Neither one ever found any land.

Image: By NOAA / Satellite and Information Service [Public domain], via Wikimedia Commons

Cape Verde Hurricane Paths Image Credit:  NOAA, PD

When a Hurricane makes all the way across, we call it a long tracker, because it has maintained its structure while traveling such a great distance.  Long trackers need several things to survive and make it across.

A PATH WESTWARD

Ever hear of the Bermuda High?  or the Azores High?  That's a big area of high pressure over the ocean, shown as the tropical ridge in the illustration.  Since the hurricane is a low pressure system, it doesn't 'mix' well with the high one.  So, the low pressure system wants to go around it.  To do that, it has to first move west, along the ridge's southern border.  That's a good example of one way atmospheric conditions can 'guide' a tropical system.  Other currents, fronts, or ridges can come into play, as well.

A WARM, MOIST ENVIRONMENT

Warm water is fuel for tropical systems.  They need it to develop, strengthen, and maintain strength.  Sea surface temperatures of 80 degrees F (26.5 C) and above are ideal.  So is nice, warm, moist air that has little or no dust in it.

FAVORABLE WINDS 

Vertical wind shear means how the winds are behaving from one level to the next higher one. If there is a big difference in direction or speed going upwards, then that's high wind shear.  Storms don't like to run into that.  It can weaken them significantly.  When there's little to no wind shear, they have a better chance to get stronger.

 Before the Storm, by Jocelyn Augustino (Public Domain image from the FEMA Photo Library)  

Bayou Vista, TX, September 12, 2008

Ike, in 2008, was a dangerous tropical cyclone that began life two weeks earlier as a tropical wave off the coast of Africa.  The picture above shows flooding on Friday.  Landfall was at Galveston Island, on Saturday.

It is worthwhile also to note that this is not an oceanfront neighborhood.  Bayou Vista is on the mainland, just across the bay from Galveston island, and about 10 miles from the famous seawall..

Not all of the storms whose names we remember so well were Cape Verde Hurricanes.  For instance, Katrina spun up over the Bahamas.  She was what we refer to as a 'home grown' storm.

Hurricane Ike's Track:

However, quite a few of the storm names that have gone down in history started out in life as a chunk of  disturbed weather over the Saharan Desert, and emerged off the coast to become a tropical wave, and eventually a hurricane, and maybe even a major one.

These are some of the history making Cape Verde storms that you may recognize, with their categories in parenthesis:

The Great Galveston Hurricane (4) - 1900.  Believed to have been a Cape Verde storm, based on reports from ships at sea. It was the deadliest natural disaster ever in the United States, with estimates of 6,000 to 8,000 deaths.  No one ever knew the real count for sure.  Galveston Island was devastated.

Hugo (5) - 1989.  Came ashore as a Cat 4 at Charleston, S.C.

Andrew (5) - 1995 .  Virtually leveled most of the buildings in Homestead, FL. 

Ivan (5) - 2004.  Numerous landfalls.    123 lives lost in the Caribbean and the US. 

Frances (4) - 2004. Affected every island in the Bahamas, much  Florida, and points north all the way into Ontario 

Emily (5) - 2005. Holds the record for the earliest Cat 5 ever. (Jul  16) 

Ike (4) - 2008. Another that wreaked utter havoc on Galveston island.  195 were killed in the Dominican Republic Haiti, Cuba, and the United States.  Another 34 were never accounted for.  In terms of  property damage, Ike was history's third costliest Atlantic Hurricane.

  Hurricane Julia's Track:

Others developed sufficiently to be classified as hurricanes, but never made it across the wide expanse of water, and dissipated at sea.  There are many storms that fit this definition.  Most of them didn't even make an impression on very many people at the time, much less the history books.  

Here are three random examples from recent years:

Cindy (4) - 1999

Danielle (2)  - 2004

Julia (4) - 2010

. . . and others