Two systems in the Northwest Atlantic — newborn Tropical Storm Humberto and emerging Invest 94L — could both become hurricanes over the next few days, perhaps inching close enough to each other for some unusual and forecast-complicating interactions. In the meantime, the central islands of the Azores were bracing Thursday for what could be the first direct hurricane landfall in the Atlantic this year and a rarity for them any year. The Azores, an autonomous region of Portugal, are located so far east that they use London-based Greenwich Mean Time (GMT or Z).
As of 11 a.m. EDT (5 p.m. GMT) Thursday, Hurricane Gabrielle was positioned about 455 mi (730 km) west of the Azores, racing just north of due east at 32 mph (52 km/h). The former Category 4 Gabrielle was down to Cat 1 strength, with cool waters taking a toll and high wind shear having snuffed out or dispersed most of the storm’s showers and thunderstorms (convection). Gabrielle’s top sustained winds were 75 mph (120 km/h), and tropical-storm-force winds extended out to about 70 mi (110 km) north and 175 mi (280 km) south of its center. It’s quite possible Gabrielle will no longer be a hurricane when it approaches the central Azores in the predawn hours Friday, but an upper low passing north of Gabrielle may impart enough downward momentum on the circulation’s south side to allow for a pocket of hurricane-strength winds. Up to 5 inches (13 cm) of rain could fall over the central Azores.
The central and southeastern islands of the Azores, near and to the south of Gabrielle’s center, are the most likely to experience the brunt of Gabrielle’s winds and surge. Of the few hurricanes that move toward the Azores, most evolve into post-tropical cyclones or weaken to tropical-storm strength by the time they arrive, and significant damage is rare. In October 2019, Hurricane Lorenzo — the easternmost Cat 5 storm on record in the Atlantic — passed 55 mi (100 km) north of Flores Island in the westernmost Azores while packing 90-mph sustained winds. Major damage was reported at the island’s dock, and sustained winds reached 74 mph at nearby Corvo Island. In January 2016, former Hurricane Alex made landfall on Terceira Island as a strong tropical storm with 70 mph sustained winds.
Humberto predicted to become a major hurricane between The Bahamas and Bermuda
A disturbance well northeast of the Leeward Islands strengthened into Tropical Storm Humberto on Wednesday. Humberto was named about two weeks later than the average formation date of the ninth Atlantic storm of the year (based on the period 1991-2020). By this point, there have typically been four Atlantic hurricanes, but 2025 has produced just two thus far, Erin and Gabrielle. Humberto appears destined to join those two before the week is out.
At 11 a.m. EDT Thursday, Humberto was centered about 465 mi (750 km) east-northeast of the northern Leeward Islands, moving northwest at 8 mph with top sustained winds up to 50 mph (85 km/h). Steering currents will keep Humberto on that general track through Sunday, with a turn toward the north-northwest expected early next week, but its motion and strength may be influenced by Invest 94L (see below).
Humberto wasn’t an especially well-organized tropical storm on Thursday, but it did sport a large area of convection, with some banding and strong upper-level outflow on its east side. Strong wind shear of 15-20 knots was restricting Humberto’s west side, and that shear will likely persist through the weekend. Nevertheless, Humberto will be traversing unusually warm waters for late September (sea surface temperatures of around 29 degrees Celsius or 84 degrees Fahrenheit), and by this weekend, it will encounter an increasingly moist air mass (mid-level relative humidity rising from 50-55% to around 65%). Wind shear may abate slightly at times, giving Humberto some windows for consolidation.
The 6Z Thursday runs of all four intensity models used by the National Hurricane Center (NHC) bring Humberto to hurricane strength on Friday or Saturday and at or near Category 4 strength by Sunday. The NHC has gradually ramped up its intensity forecast, now explicitly predicting rapid intensification to Cat 3 strength from Saturday to Sunday.
One to watch for The Bahamas and the U.S. East Coast: Invest 94L
Humberto may well take a cue from Hurricanes Erin and Gabrielle and avoid any landfalls in the Americas or the Caribbean, but the disturbance just to its west, 94L, could chart a different course. The Tropical Weather Outlook issued by the NHC at 2 p.m. EDT Thursday gave 94L an 80% chance of becoming at least a tropical depression over the two days through Saturday morning, and a 90% chance over the 7-day forecast period. The NHC added: “While there is significant uncertainty in the long-range track and intensity of the system, the chances of wind, rainfall, and storm surge impacts for a portion of the southeast U.S. coast are increasing.”
Heavy rains associated with 94L brought widespread totals up to 2 in (5 cm) across Puerto Rico through Thursday morning, with a CoCoRaHS report of 4.46″ (11.33 cm) on the south coast near Ponce. Squalls with torrential rain were pushing across the eastern Dominican Republic on Thursday afternoon.
94L is predicted to head northwest in tandem with Humberto, and their fates may end up tightly connected. Tropical cyclones within about 850 miles (1350 km) of each other tend to rotate around each other as they move within the steering flow, a dance known as the Fujiwhara effect (see this handy explainer from the Hong Kong Observatory). The effect is more commonly seen in the Northwest Pacific, where there are typically more tropical cyclones than in the Atlantic. As of midday Thursday, Humberto and 94L were roughly 800 miles (1300 km) apart.
In such a Fujiwhara dance, the path of the weaker system (Invest 94L in this case) is usually the one more strongly influenced. Sometimes the two systems will merge if they’re close enough, although this doesn’t appear likely to happen with Humberto and 94L. Assuming that 94L does develop on its own, it appears that any Fujiwhara effect would tend to keep it moving more slowly and perhaps with more of a westward component than Humberto.
94L is expected to reach the Bahamas around Sunday, perhaps as a tropical storm. It’s too soon for intensity models to give us a solid sense of how strong 94L might ultimately get, especially with any Humberto interaction still uncertain. What’s more, part of a large upper low moving across the eastern U.S. is predicted to cut off over the Southeast this weekend, which could help steer 94L northward or northwestward. The timing and strength of all these features (Humberto, 94L, and the cut-off low) and how they interact will be extraordinarily difficult to parse — and all this will play out atop regional waters that are close to record warmth for late September (see embedded post below).
A large share of ensemble members from the GFS and especially the European model do bring 94L toward the Southeast U.S. Coast next week, so this one bears close watching.
The next name in the Atlantic list is Imelda, a name used for the first time in 2019. That Imelda was an unusually destructive tropical storm that produced massive flooding in southeast Texas, taking 7 lives and inflicting $5 billion in damage. Imelda is one of the costliest Atlantic storms on record whose name wasn’t retired.
Jeff Masters contributed to this post.
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