Dominican Republic hit by an ‘easterly wave’
We are now nearly a month into the Atlantic hurricane season and there hasn’t been a named cyclone in the Atlantic.
They have, so far, been confined to the eastern Pacific.
NOAA’s Climate Prediction Center is forecasting a 75 percent chance that the 2018 Atlantic hurricane season will be near – or above – normal. Similar figures have been produced for the Pacific.
Despite the lack of named storms, an easterly wave still brought destruction and flooding rains to the Dominican Republic over the weekend.
Most Atlantic hurricanes start as clusters of thunderstorms over tropical Africa. These are usually prompted by the Ethiopian Highlands, but often do noticeable damage in, for example, Sudan, Chad, Nigeria or the Ivory Coast.
The fatal floods in Abidjan on Tuesday were from such an easterly wave. There is currently, Sunday, one thunderstorm cluster over the Niger, Chad and Nigeria border and another over southern Mali. Mongo in western Chad reported 43mm from the first cluster; Ouagadougou in Burkina Faso reported 42mm from the other.
These two easterly waves will either disperse or follow the steering wind which, for easterly waves, is simply called an “easterly”.
So begins the journey across the tropical Atlantic towards the Caribbean and the US. Given just one more push from the right atmospheric conditions, a hurricane will be born.
What happened in the Dominican Republic was the result of an easterly wave that failed to develop beyond a cluster of violent thunderstorms. Nevertheless, it was stormy.
On the way in, these thunderstorms dropped 44mm of rain onto San Juan in Puerto Rico. The island has only recently re-commissioned its weather radar, in time to follow the storms. It was destroyed by Hurricane Maria last September.
In the Dominican Republic, Jean Suriel, a local meteorologist, reported island-wide torrential rain on Saturday. Pictures show mature trees downed and large signs on metal poles felled onto unfortunate cars.
The hurricane threat is in its early stages at the moment and it is normal for significant activity to happen only in the second half of the season.