Rafael expected to affect the Cayman Islands and Cuba as a hurricane » Yale Climate Connections

Hurricane Warnings are up for the Cayman Islands and western Cuba for Tropical Storm Rafael, which formed at 5 p.m. EST Monday over the warm waters of the Western Caribbean. Rafael is expected to intensify into a Cat 1 hurricane on Tuesday night and bring hurricane conditions to the Cayman Islands tonight and to western Cuba Wednesday.

Rafael’s formation gives the 2024 Atlantic hurricane season 17 named storms, 10 hurricanes, four major hurricanes, and an accumulated cyclone energy (ACE) index of 148 (26% above average). An average season has 14 named storms, seven hurricanes, three major hurricanes, and an accumulated cyclone energy (ACE) index of 117. 

Rafael still in the organizing phase

At 10 a.m. EST Tuesday, November 5, Rafael was located 200 miles (320 km) east-southeast of Grand Cayman, headed northwest at 13 mph (20 km/h) with top sustained winds of 60 mph (95 km/h) and a central pressure of 994 mb. Cayman Islands radar showed that Rafael was bringing heavy rain showers to Jamaica and the Cayman Islands. A personal weather station located about 10 miles west of Kingston, Jamaica, recorded 3.54 inches (90 mm) of rain in the nine hours ending at 11 a.m. EST Tuesday.

Satellite images showed Rafael had a modest amount of heavy thunderstorms that were steadily growing more organized, and the storm may be beginning to build an eyewall and develop an inner core. Conditions were very favorable for development, with light wind shear of 5-10 knots, a very moist atmosphere, and very warm ocean waters of 30 degrees Celsius (86°F) – about 0.5 to 2 degrees Celsius (1-2°F) warmer than average for early November. The Caribbean as a whole is close to record warmth for this time of year, roughly tied with 2023 and well above other previous years, according to sea surface temperatures analyses from the University of Arizona.

Forecast for Rafael in the Western Caribbean

A ridge of high pressure to the northeast of Rafael will keep the storm moving on a mostly northwesterly track through Thursday, taking the center of the storm about 40 miles (80 km) west of the western tip of Jamaica around 2 p.m. EDT Tuesday afternoon, then between Grand Cayman and Little Cayman Islands near 11 p.m. Tuesday.

On Wednesday morning, Rafael is expected to make landfall in western Cuba. Very favorable conditions for development are expected through landfall in Cuba, with light wind shear, warm waters with high heat content, and a very moist atmosphere. This will likely result in steady to rapid intensification, with Rafael being near Cat 1 hurricane strength tonight in the Cayman Islands and near Cat 2 strength Wednesday morning near western Cuba. The 6Z Tuesday runs of the HWRF, HMON, and HAFS-A dynamical hurricane models predicted that Rafael would be a borderline Cat 1 or Cat 2 hurricane on Wednesday morning, while the HAFS-B model was more aggressive, predicting a Cat 3 landfall in Cuba. The 12Z Tuesday SHIPS model gave a 29% chance that Rafael would rapidly intensify to a Cat 1 with 85 mph winds by Wednesday morning when the storm would be hitting western Cuba.

Rafael’s impact on Cuba: a major threat to electric power

Rafael is expected to make landfall in Cuba at an inopportune time, as the island’s electrical grid is suffering continued instability after a nationwide blackout on October 18-21 caused by the failure of the Antonio Guiteras power plant, Cuba’s largest. The latest National Hurricane Center forecast has Rafael maintaining hurricane strength as it passes over western Cuba, with the center tracking about 30 miles (50 km) west of the capital city of Havana (population 2.1 million). This track would put the city in the dangerous right-front quadrant of the storm, resulting in severe wind damage. Cuba’s electrical infrastructure is so weak that the large number of power outages likely to occur in western Cuba may have an extended duration, and the nation’s entire grid may be at risk of collapse.  

Rafael expected to be sheared apart in the Gulf of Mexico

Passage over western Cuba is likely to disrupt Rafael somewhat, but once the storm emerges into the Gulf of Mexico, it is expected to move to the northwest over a tongue of warm waters of 27-28 degrees Celsius (81-82°F) associated with the Loop Current, which extends northward from the Western Caribbean into the central Gulf of Mexico. All four of the high-resolution dynamical hurricane models make Rafael at least a Cat 2 in the central Gulf by Thursday.

The strength and positioning of an upper-level low over the central U.S. that will be steering Rafael late this week has a large uncertainty, and the National Hurricane Center commented in its 10 a.m. EST discussion that the track forecast for Rafael over the Gulf has higher uncertainty than usual. The GFS model and its ensemble members predict a continued northwesterly motion for Rafael, with the storm approaching Louisiana late in the week. However, the UKMET model and the European model and its ensembles argue for a westward turn in the Gulf, well south of the northern Gulf Coast (Fig. 2).

Regardless of Rafael’s eventual track in the Gulf, the storm is expected to be sheared apart late this week by high wind shear combined with dry air, and most of the models predict that Rafael will not make landfall in the U.S. as a tropical storm. Recurring fall cold fronts have spread cool air over the Gulf in recent weeks, causing significant cooling of the waters. The waters within about 200 miles (320 km) of the northern Gulf of Mexico coast have chilled down to below 26 degrees Celsius (79°F). More importantly, the jet stream has shifted more to the south in recent weeks, and thus Rafael will encounter high wind shear of 20-30 knots if it approaches the U.S. coast. In addition, very dry air with a midlevel relative humidity of 45-50% is expected over the central and northern Gulf late this week.

There is the potential for areas of heavy rain over the Southeast U.S. from a moist flow of air in advance of the storm, as Rafael is embedded in an unusually large area of atmospheric moisture for early November. The National Weather Service has placed much of Georgia and southwestern South Carolina in its “Slight Risk” area for excessive rain on Wednesday, and three to five inches of rain might fall there, with locally higher amounts.

Another disturbance could move through the Bahamas toward South Florida late this week

The tail end of a Northwest Atlantic cold front may attempt to organize late this week into a tropical disturbance that will organize on Friday over the southeastern Bahamas then move west to west-northwest toward South Florida. A few members of the European model ensemble, and most of the members of the GFS model ensemble, show development of this disturbance into a tropical depression or weak tropical storm. There is relatively high confidence in the steering pattern, and sea surface temperatures remain unusually warm — more than adequate to support a tropical cyclone. However, wind shear and the upper-level wind structure will be less than ideal.

In its Tropical Weather Outlook at 7 a.m. EDT Tuesday, the National Hurricane Center gave this future system a 20% chance of developing into at least a tropical depression in the seven-day period, with near-zero odds in the two-day window.