At a Glance
- One big question with Dorian: Will it survive its track through the eastern Caribbean?
- Conditions there can often be hostile to tropical cyclones.
- Several tropical systems over the past few years dissipated in the eastern Caribbean.
Tropical Storm Dorian faces a challenging path for strengthening as it will track through parts of the eastern Caribbean, which is sometimes referred to as the "hurricane graveyard" by meteorologists because many tropical cyclones have met their demise in the region.
A study published in 2009 found that conditions can be harsh for tropical development in the eastern Caribbean. Specifically, trade winds spreading apart at low levels, sinking air and increased wind shear create a hostile environment for some tropical cyclones, especially earlier in the Atlantic hurricane season.
Dry air can also limit tropical development in the region. All these factors make it difficult for thunderstorms to develop and organize.
Strong hurricanes, however, are not typically influenced by this hurricane graveyard effect – weaker systems are more susceptible. Additionally, conditions become more favorable later in the season for tropical cyclone development in the eastern Caribbean as the Caribbean low-level jet weakens and shifts eastward.
What To Watch With Tropical Storm Dorian
Tropical Storm Dorian is moving through the eastern Caribbean and has been battling dry air over the past few days, limiting intensification.
(MORE: Tropical Storm Dorian Forecast)
Dry, sinking air disrupts tropical systems by suppressing thunderstorms and not allowing them to persist long enough near the center.
Strong wind shear – the change in wind speed and direction with height – can also be detrimental to the strengthening of a tropical cyclone because it can push the tops of thunderstorms away from the center of the storm, disrupting its circulation.
Wind shear is expected to increase as Dorian gets closer to the Dominican Republic later this week, which could hinder intensification.
Interaction with land will also be very important in determining if Dorian survives its track through the Caribbean. It moved over St. Lucia Tuesday morning, which "resulted in significant disruption of the small inner-core wind field," according the the National Hurricane Center.
The center of Dorian may pass over Puerto Rico and the Dominican Republic, which would likely weaken the storm further. Interaction with land can disrupt tropical systems and the tall mountains of Hispaniola are known for this potential.
If Dorian moves between the islands, it has a greater chance of staying intact as it moves toward the Bahamas.
Dorian is also a relatively small tropical storm, which makes it more difficult to forecast – especially its intensity.
Smaller systems can rapidly strengthen or weaken due to small changes in the environment, so Dorian may be more impacted by the conditions along its path through the eastern Caribbean.
(MORE: Why Small Tropical Storms and Hurricanes Can Be Difficult to Forecast)
Recent Storms That Ended in the Eastern Caribbean
Last year, two tropical cyclones dissipated in the eastern Caribbean.
Isaac was a small hurricane that developed in the eastern Atlantic in early September. However, as it tracked westward, it weakened and ended its track in the eastern Caribbean due to strong upper-level winds and dry air.
Tropical Storm Kirk formed in the eastern Atlantic in late September. Strong wind shear also ripped Kirk apart as it moved into the eastern Caribbean, but it caused heavy rain, flooding and strong winds in St. Lucia and Barbados.
In 2015, Hurricane Danny and Tropical Storm Erika also met similar fates. Danny formed in mid-August and became a major hurricane (Category 3 or higher). However, strong wind shear near the Caribbean caused it to dissipate.
Tropical Storm Erika developed in the eastern Atlantic in late August 2015 and brought strong winds and heavy rain to Dominica, the Dominican Republic and Haiti. Some gusty winds were also reported in Puerto Rico and the U.S. Virgin Islands.
Erika encountered strong wind shear and dry air, which made it difficult for the system to strengthen. It was also impacted by the higher terrain of the Dominican Republic and Haiti, as well as eastern Cuba. Erika dissipated near Cuba due to these factors.
Sometimes, tropical cyclones dissipate in the Caribbean but are able to reform later. Hurricane Harvey developed in mid-August 2017 east of the Caribbean but then degenerated into a tropical wave as it moved through the Caribbean. Its remnants moved into the southwestern Gulf of Mexico, where conditions were favorable for development; it was able to become a major hurricane before making landfall in Texas.
Another way to look at this is to examine how many tropical storms in the eastern Caribbean were able to become hurricanes east of Haiti. There are very few examples, with the most recent being Hurricane Matthew in 2016.
Matthew formed just east of the Lesser Antilles in late September and was able to strengthen, becoming a hurricane as it moved through the eastern Caribbean. Matthew became a major hurricane and made landfall in Haiti before impacting the Bahamas and later making landfall in South Carolina.