The National Hurricane Center is closely monitoring Invest 91L, a tropical wave in the eastern Atlantic that forecasters say could develop into a tropical depression in the coming days as it moves toward the Caribbean.
As of Friday evening, the tropical disturbance was battling dry air as it moved westward across the Main Development Region, a zone between the west coast of Africa and the Caribbean. The NHC noted that the very dry air was limiting development from occurring.
Notably, on Friday evening, the NHC decreased the chances of further development of Invest 91L. Still, the agency said that the system has a medium, 60% chance of becoming a tropical depression in the next seven days, and a low, 30% chance of development in the next 48 hours.
“Shower and thunderstorm activity remain limited in association with a tropical wave over the central tropical Atlantic,” according to an 8 p.m. update on Friday from the NHC. “A drier air mass is limiting the potential for development over the next couple of days, and environmental conditions will remain only marginally favorable thereafter. A tropical depression could form during the early to middle part of next week as the system moves westward at around 10 mph across the central tropical Atlantic.”
“This system is likely to be near the Lesser Antilles by the middle to latter part of next week, and interests there should monitor its progress,” the NHC added.
Several of the widely used computer forecast models had predicted that the storm could potentially intensify into at least a tropical storm. If the system is ultimately able to organize and reach tropical storm strength, with maximum sustained winds of at least 39 mph, it will be designated “Gabrielle,” the seventh named cyclone of this year’s Atlantic hurricane season.
Where Will the System Track?
As of Friday, the path of Invest 91L remains very uncertain. However, there is some consensus among the computer models that — if a cyclone indeed develops — the storm may come close to the Caribbean, and it could cause impacts to certain islands across the Lesser Antilles or Leeward Islands during the second half of next week.
Meteorologists with AccuWeather have noted the possibility of areas across the Caribbean experiencing effects from the system, while cautioning that the forecast can change in the coming days.
The Source reached out to Alex DaSilva, lead hurricane specialist at AccuWeather, for clarification on what could occur and if the U.S. Virgin Islands could, in fact, be impacted by the developing cyclone.
DaSilva stressed that while some development of this disturbance is likely, environmental conditions will play a major role in how strong the system becomes.
“At the current time, we don’t think that it’s likely to undergo rapid intensification and become a major hurricane, given the current atmospheric conditions. Confidence in it becoming a hurricane is moderate right now, and it has to deal with a lot of dry air, especially over the next 48 hours, as it continues to move west,” DaSilva told the Source.
DaSilva went on to say that the storm’s track remains uncertain until a well-defined center develops.
“The track is still a little unclear, because the cluster of showers and thunderstorms has not fully consolidated around a center of circulation,” DaSilva said.
He noted that if the system takes a northern track, forecasters say it could remain weaker, but a southern path could mean more favorable conditions.
“If the storm ends up more on the northern side of the track, it might end up weaker, because it will run into more wind shear north of the islands. That could really limit development, but it would still likely bring some rain to the islands.”
“However, if Invest 91L is able to remain a little bit farther south and avoid some of that wind shear, that’s how it could end up being potentially a little bit stronger,” he added.
DaSilva said that, overall, it is too early to know exactly what might occur, as a lot depends on how quickly Invest 91L is able to organize.
“We will need to wait and see if the disturbance is able to make it through some of the dry air, especially early in a tropical cyclone’s lifetime, when the dry air can be more of a limiting factor in terms of development. Once a storm is able to get established and really get that core, it can fight off some of that dry air,” DaSilva stated.
“This is an evolving situation and things can change pretty quickly,” he noted.
National Weather Service in San Juan Monitoring Situation
On Friday, the National Weather Service in San Juan, Puerto Rico, cautioned that it is still too early to determine whether there could be any direct impacts across the USVI or Puerto Rico. While acknowledging the potential threat posed by Invest 91L, the agency advised that residents and visitors across both U.S. territories remain vigilant and monitor the progress of the tropical wave.
“The approximate timeframe of interest is September 12 to 15,” the NWS said. “However, uncertainty remains regarding the system’s trajectory and intensity. At this time, it is too early to determine potential impacts on Puerto Rico or the U.S. Virgin Islands.”
“Please remain engaged and continue monitoring official updates through the weekend,” the NWS advised.
Local Weather Information and Staying Informed
Looking ahead, additional tropical waves are anticipated to emerge off the west coast of Africa in the next few weeks, and USVI residents and visitors are encouraged to continue to remain prepared.
“The Caribbean islands need to be watching all of the tropical waves as they come west, because I believe there will be a risk of impacts throughout the rest of September, and even into the beginning of October,” DaSilva said.
It is crucial to remember that the forecast can change very quickly. USVI residents and visitors are encouraged to continue to remain prepared. Weather information is available from the NWS, the NHC, and NOAA.
Additionally, the local weather forecast for the U.S. Virgin Islands is regularly updated on the Source Weather Page and VI Source YouTube Channel. A weekly Tropical Outlook article from the Source is also published throughout hurricane season to provide in-depth updates. Residents and visitors can find additional weather alerts and preparedness information from the Virgin Islands Territorial Emergency Management Agency.