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Tropical storm weather forecast updates are drawing attention to Invest 99L, a developing disturbance in the open Atlantic that could soon become Tropical Depression Six. The system was rapidly organizing southwest of the Azores on Friday, September 18, according to the National Hurricane Center.
Forecasters said Invest 99L had an 80% chance of becoming a tropical cyclone within 48 hours. If it strengthens into a tropical storm, it would receive the name Fay, making it the Atlantic’s sixth named storm of the 2026 hurricane season.
Powerful Tropical Storm Weather Forecast Centers on Invest 99L
Invest 99L is positioned in an area that currently supports tropical development. Wind shear is low, while ocean temperatures are in the 80s. Those conditions can help a tropical disturbance organize thunderstorms and develop a more defined circulation.
The National Hurricane Center forecast the system to become Tropical Depression Six on Saturday, September 19. However, the disturbance is not expected to move toward the United States immediately. It is forecast to remain southwest of the Azores before turning southwest early next week.
That projected track could eventually carry Invest 99L into an environment less favorable for development. The National Hurricane Center said conditions may become more hostile by Sunday night or Monday as wind shear increases and other atmospheric factors begin to weaken the system.
Could Invest 99L Become Tropical Storm Fay?
The next named storm on the Atlantic list is Fay. If Invest 99L reaches tropical-storm strength, it would become the sixth named storm of the year. Even so, the system’s expected development would not necessarily signal a major shift toward an active hurricane pattern.
- Invest 99L is located in the open Atlantic southwest of the Azores.
- The system has an 80% chance of tropical cyclone formation within 48 hours.
- It could become Tropical Depression Six on Saturday.
- Further strengthening could result in the name Fay.
- Conditions are expected to become less favorable after Sunday.
Historic Atlantic Hurricane Season Remains Unusually Quiet
The latest tropical storm weather forecast comes during an extraordinary lull in Atlantic activity. The basin has produced only five named storms, with no hurricanes or major hurricanes so far this season.
FOX Weather reported that the Atlantic has reached its latest date without a hurricane forming since the beginning of the satellite era. In a typical season, the Atlantic produces about 14 named storms, seven hurricanes and three major hurricanes.
A strengthening El Niño is a major factor behind the slow pace. El Niño often increases upper-level winds across the Atlantic, creating wind shear that can tear apart developing tropical systems. At the same time, the climate pattern can support more activity in the Pacific.
Forecasts suggest this El Niño could become unusually strong, potentially reaching “super” status. That possibility has made it more difficult for tropical waves emerging from Africa to organize in the Atlantic’s Main Development Region.
Central American Gyre Could Bring New Tropical Threats
Long-range forecasts are also monitoring the possible development of a Central American Gyre next week. A Central American Gyre is a broad area of low pressure that can form near or over Central America.
These sprawling weather systems can produce heavy rain, rough surf and mudslides. They may also help generate tropical systems in the Gulf of Mexico or the eastern Pacific. According to the FOX Forecast Center, Hurricane Idalia in 2023 developed in connection with a Central American Gyre.
The Climate Prediction Center’s two-week tropical outlook also indicates a lower-end possibility for development near the Southeast Coast and the eastern part of the Main Development Region. That outlook is not a specific storm forecast, but it highlights areas forecasters will continue to monitor.
What Residents Should Watch Next
For now, coastal residents should avoid jumping to conclusions about Invest 99L. The system remains far from land, and its projected path is expected to keep it over the Atlantic. Still, tropical weather can change quickly, particularly when a disturbance enters warmer water or encounters weaker wind shear.
People across the Caribbean, the Bahamas and the U.S. East Coast should continue checking official updates from the National Hurricane Center. Travelers and boaters in the Atlantic should also monitor changing marine conditions, including higher waves, stronger winds and rough surf.
Frequently Asked Questions
What is Invest 99L?
Invest 99L is an area of disturbed weather being monitored for possible tropical cyclone development. The designation allows forecasters to collect and analyze additional information about the system.
Could Invest 99L become Tropical Storm Fay?
Yes. If the system strengthens enough to reach tropical-storm status, it would receive the name Fay. Before that happens, it is forecast to become Tropical Depression Six.
Where is Invest 99L located?
Invest 99L is in the open Atlantic several hundred miles southwest of the Azores. It is expected to remain away from the United States in the near term.
Why has the Atlantic hurricane season been so quiet?
A strengthening El Niño has increased wind shear across the Atlantic, making it harder for tropical systems to organize. The basin has recorded five named storms but no hurricanes so far.
What is a Central American Gyre?
A Central American Gyre is a broad low-pressure system near Central America. It can bring heavy rainfall and flooding while sometimes helping tropical systems form in nearby waters.
