Three Systems Being Watched
Today marks the first anniversary of Hurricane Helene making landfall along the Big Bend region of Florida, which ultimately initiated a very active four-week period in last year's hurricane season, with eight named storms occurring within 30 days. Luckily, this type of hyperactivity is not expected to persist over the next 30 days. However, the season isn’t over yet, with three tropical systems being monitored across the Atlantic Basin; there may still be some trouble later in October..
Shortly after our last BMS Tropical Update posted on 9/24/2025, Invest 93 was upgraded to the 8th named storm of the 2025 Atlantic Hurricane Season (Humberto), and just this morning, it was upgraded to the third hurricane of the season.
Late last night, Hurricane Gabrielle was downgraded to a post-tropical cyclone about 265 miles (425 km) west-southwest of the Azores, which means the 2025 Atlantic Hurricane Season still hasn’t had a landfalling hurricane anywhere across the Atlantic Basin. This doesn’t mean Gabrielle didn’t have an impact on the Azores. It appears that the strongest peak wind gust was 76 mph, with hurricane conditions affecting the island, accompanied by rainfall of 3-5 inches over much of the central islands.
The National Hurricane Center (NHC) continues to monitor a tropical wave (Invest 94L) located over the eastern end of Cuba, which has an 80% chance of developing within the next 2 days and a 90% chance of developing within the next 7 days. Invest 94L is likely to become future Imelda and a threat to the U.S., which will be the major focus of this BMS Tropical Update.
It should be noted that Invest 94L has already left its mark across the northern Caribbean islands, bringing widespread rainfall of 1 to 4 inches across Puerto Rico, with the heaviest totals reported in the southern parts of the country. This heavy rainfall brought some flooding and landslides across Puerto Rico.
The Uncertainty That Lies Ahead
In the last BMS Tropical Update, we discussed the compacted forecast for Invest 93, now known as Humberto, and Invest 94L. Due to Humberto's quicker development, there is more certainty surrounding its overall endgame. Like the other two hurricanes this season, Erin and Gabrielle, Humberto is also expected to become a major hurricane, likely Category 4, following a similar path to Erin earlier this year, but maybe slightly closer to Bermuda. In fact, there is a high likelihood of rapid intensification due to low wind shear and warm ocean temperatures over the next few days. Humbert could pose a threat to Bermuda sometime early to the middle of next week, as Bermuda is located within the NHC cone of uncertainty. Remember, the NHC forecast cone is based on the previous 5 years, with an average error of 213 miles in a 5-day forecast. The multi-model ensemble suggests a 55% chance that Humberto will track within 100 miles of Bermuda. As Humberto is expected to be located near Bermuda next week, it will likely be a Category 3 hurricane, but in a weakening state. Any crazy forecast that you might have seen earlier in the week, suggesting it might merge with Invest 94L or loop back around to the U.S. Coastline, seems to be off the table at this time.
The fundamental forecast uncertainty is with Invest 94L or soon-to-be Imelda. Invest 94L is still interacting with Hispaniola this morning. This is preventing a low-level circulation from forming. Various forecast models continue to be consistent that a circulation will form over the Southeast Bahamas tonight/tomorrow and move off to the northwest towards the Carolinas. There's still considerable uncertainty about where Invest 94L could go. Most computer forecast models provide the same three scenarios that we outlined in the last BMS tropical update.
All the models agree that Invest 94L will move northward through or near the Bahamas through Sunday. Beyond that, the forecast is still very uncertain with three scenarios in play:
- Invest 94L could continue moving north-northwest and make landfall in the Carolinas as either a tropical storm or weak hurricane early next week.
- Invest 94L could stall for an extended period of time next week near the Southeast coast or inland.
- Invest 94L could stall off the Southeast coast for a day or two early next week before being pulled east away from the coast, possibly toward Bermuda behind Humberto.
The biggest question for the insurance industry is what the intensity will be. If Invest 94L approaches Florida closely enough, it could limit development due to land interaction. If it develops and tracks more to the eastern Bahamas, it could be influenced by Humberto's outflow, which would increase wind shear. Hurricane models continue to depict a very asymmetric structure with dry air on the south side of the circulation, which could limit its top-end intensity. However, there is plenty of deep, warm ocean water that could fuel development over the Gulf Stream. At this time, the most likely outcome is that Invest 94L is a strong TS or Category 1 hurricane near the southeast coastline early next week.
Possible Impacts Invest 94L
With the understanding that Invest 94L isn’t yet a named storm and its track and intensity are unknown, we can say with some degree of confidence that it will have some impact on the U.S. Even if Invest 94L doesn't ever make landfall in the U.S., days of onshore winds are likely to generate high surf, beach erosion, and maybe isolated areas of coastal flooding along the Florida coastline, because Humberto will create lots of large waves that will work their way to the East Coast.
Of course, depending on how strong Invest 94L is, it could result in strong wind gusts along parts of the Southeast coast, even if it never makes landfall, as Hurricane Erin did in August. However, even if Invest 94L becomes a Category 1 hurricane and makes landfall, this should result in low levels of wind-related losses to the insurance industry. We will need to examine this in more detail once we determine Invest 94L's intensity.
Perhaps the most significant issue, not uncommon with Named Storms, is that water is the new wind, posing a serious threat of heavy rain given the potential for Imelda to stall for at least a few days near the coast. Similar to Hurricane Helene last year, a setup is in place that could lead to locally heavy rain over parts of the Southeast ahead of Invest 94L through this weekend.
Despite some ongoing drought, this rain-soaked ground could enhance the flood threat if Invest 94L makes landfall or is close enough to spread bands of heavier rain into those areas next week. And remember that this rainfall threat could extend well inland, including parts of the Appalachians and the mid-Atlantic.
Not ideal, but the insurance industry will have to stay tuned. To understand the impacts, consider rainfall impacts, as wind impacts should be manageable based on the current worst-case forecast intensity from the various models. Still, as we have outlined, there is considerable uncertainty, and these BMS Tropical Updates will provide more detail on the impacts as more information becomes available.