Forecasters revise hurricane predictions

John Tibbetts, director general of the Cayman Islands National Weather Service, explains some recent weather formations in the area on screens at his office. - Photo: Taneos Ramsay

Although the 2019 hurricane season got off to a slow start, things have been heating up in the Atlantic Basin. So far, 12 named storms, four hurricanes and two major hurricanes have formed and battered multiple countries in the region.

The initial activity has since forced forecasters to rethink their pre-season predictions for a “quiet season”.

Each year, the Cayman Islands National Weather Service aligns its predictions with Colorado State University, as well as the National Oceanic and Atmospheric Administration in the US.

Initial predictions from Cayman Islands National Weather Service and Colorado State University called for 13 named storms, five hurricanes and two major hurricanes. While NOAA’s initial predictions called for nine to 15 named storms, four to nine becoming hurricanes, and two to four of those becoming major hurricanes.

The pre-season predictions called for a 30% probability of an average season, which according to NOAA is a season with 10.1 named storms, 5.9 hurricanes and 2.5 major hurricanes. Major hurricanes are storms category 3 and above.

“For the most part, the observed hurricane activity has been far more active in the sense that we have had way more powerful storms,” said Jhordanne Jones, a Ph.D. student at Colorado State University. “Even though we have had two major hurricanes, they have been far more intense than we initially predicted.”

Hurricane Dorian, at category 5, was the most powerful storm to form this season. It claimed more than 50 lives in the Bahamas and racked up more than US$$2 billion in damages across the eastern Caribbean and the US east coast.

Jones says initial models suggested an active El Nino was over the Caribbean area. El Nino and La Nina (Spanish for ‘little boy’ and ‘little girl’) refer to the heating and cooling of the tropical belt. For the Caribbean, an El Nino helps to suppress the creation of storms, while a La Nina increases the chances.

With some 10 weeks to go before the season ends, El Nino is now becoming weaker. The shift in weather conditions is part of the reason why forecasters are now calling for a 45% probability of an average season.

The revised projections have seen the overall number of predicted storms increase from 13 to 14. This means forecasters expect as many as two more named systems, both of which could become hurricanes.

Cayman and the wider western Caribbean have seen little to no storm activity so far. However, John Tibbetts, director general of Cayman’s National Weather Service, says now that the peak of the season has been reached, that could change.

“The ones [storm systems] that start to really concern us, is when we get into the month of October,” said Tibbetts. “Some of these storms start to form in the western Caribbean.”

Tibbetts said that with the shift in storm development comes a higher risk for Cayman.

“The problem with them is two-fold,” he said. “One, that time of year, the sea’s water is really warm, and so the possibility for rapid intensification exists. Number two is that, being that they are already in the western Caribbean, they have a tendency to maybe shorten our warning times. So, one day you might be looking at a tropical wave or a tropical depression, all of a sudden, you have a major hurricane at your doorstep.”

In order to increase the accuracy of storm predictions, the Caribbean region will need to invest in equipment that tracks weather conditions, as well as increase the reporting of the country-by-country observations. Investing in weather tracking and forecasting equipment is a pricy endeavour, which Jones says most Caribbean countries will not have to face for now.

“There are enough resources to help monitor hurricane activity, perhaps more on land than at sea. I am not particularly sure of any observation systems that belong to the Caribbean, that is currently within the Caribbean sea,” said Jones.

While the accuracy of predictions has dramatically increased over the years, Tibbetts says there is still room for improvement. To increase accuracy, Jones says it will require more effort from all the Caribbean countries.

“One of our predictors is actually Caribbean Zonal Winds – they are winds that move from east to west or from west to east, and those contain a lot of predictability,” said Jones. “It would definitely help if we had way more observation of the Caribbean.”

The last hurricane to make landfall in Cayman was Hurricane Paloma in 2008. Paloma pummelled Cayman Brac with 140 mph winds and left much destruction in its wake.