Bryan Norcross: Complex pattern over the Atlantic yields uncertain threat for the Southeast coast
There are too many imaginable scenarios to enumerate, but the bottom line is that everyone in the Bahamas and along the U.S. East Coast from Florida to the mid-Atlantic should plan to stay informed this weekend.
Atlantic Basin sees trio of tropical threats
The tropical Atlantic Basin is booming with activity as forecasters monitor Hurricane Gabrielle, Invest 93L and Invest 94L. FOX Weather Hurricane Specialist Bryan Norcross uses his expert analysis to break down the tropical threats on Sept. 24, 2025.
Updated at 10:45 a.m. ET on Wednesday, Sept. 24, 2025
The National Hurricane Center has designated two "invests" – tropical systems they are investigating with special computer models. Invest 93L is a large system in the central tropical Atlantic surrounded by dust and dry air. It already has winds over 40 mph, so it will become Tropical Storm Humberto as soon as the NHC determines there’s a closed circulation.
Invest 94L is a disorganized system nominally centered near Puerto Rico and the Virgin Islands that’s producing pockets of heavy rain over the entire northeast Caribbean.
WHAT IS AN INVEST DURING HURRICANE SEASON
This is satellite imagery of the tropical Atlantic.
(CIRA / FOX Weather)
The atmospheric pattern over the eastern U.S. and the western half of the Atlantic is extremely complex. Besides the two invests, there is a relatively small upper-level low just east of the Bahamas and a very large, upper-level low-pressure area over the Southeast.
Exactly how these systems are going to interact over the next week to 10 days is open to question. There is more agreement among the various computer forecasts this morning, but it’s still a very complex set of scenarios.
The two invests are forecast to track close enough to each other so that they affect each other's track and intensity next week. Some computer forecasts actually merge the two systems, though fewer today. Others develop two strong hurricanes.
Assuming the two systems stay independent and don't interact in a significant way, Invest 93L looks likely to head in the general direction of Bermuda. The National Hurricane Center is giving it a very high chance of developing, but most computer forecasts predict it will develop into a tropical storm fairly soon, and eventually a strong hurricane. The current forecast consensus calls for it to be in the general vicinity of Bermuda next Tuesday or Wednesday.
This is FOX Weather's exclusive Tropical Threat analysis.
(FOX Weather / FOX Weather)
Invest 94L
The small upper-level low is currently creating a hostile environment for Invest 94L. Over the next couple of days, the upper low should exit the picture, leaving an atmospheric pattern that will be more conducive to development. The system should be over or near the Bahamas at that time.
The best evidence is that Invest 94L will be crawling when it reaches the southeastern Bahamas. It will be caught between the large circulation around Invest 93L or likely-Humberto trying to hold it south and the large low-pressure area over the Southeast that will want to scoop it north.
Early to mid-next week, the distance between whatever kind of systems invests 93L and 94L become (likely Humberto and Imelda) will be shrinking and the big upper low over the Southeast will be pulling away, so we have very little confidence in the long-range forecasts.
If the systems are both strong enough to resist each other, they will want to rotate in a counterclockwise direction around a nominal center point. But if they are significantly different in intensity, the interaction is impossible to predict.
There are too many imaginable scenarios to enumerate, but the bottom line is that everyone in the Bahamas and along the U.S. East Coast from Florida to the mid-Atlantic should plan to stay informed this weekend.
Forecasts for just-developing systems are always iffy. In this case, we have two of them. As long as they don't have a clear center to track, we can expect big changes from one forecast cycle to the next.
This graphic shows the overview of the tropical Atlantic.
(Bryan Norcross / FOX Weather)
Hurricane Gabrielle
Gabrielle is speeding across the North Atlantic. Upper-level winds are becoming more hostile, and the water under the storm is getting progressively cooler. It's still expected to be a formidable hurricane when it reaches the Azores late Thursday into Friday. Hurricane conditions can be expected over much of the island chain.
The system will weaken and become a non-tropical type of storm over the weekend. The current forecast calls for it to impact Portugal or northwestern Spain.
This hurricane season
Obviously, this has been an unusual hurricane season. We had a long stretch with no activity, and the two hurricanes we've had so far were extremely strong. Now, two more strong hurricanes could develop.
This might end up being a season with fewer total named storms than average, but that doesn't mean that it won’t be impactful. Remember last year when hurricanes Helene and Milton both formed after this date.
We can thank Mother Nature for the big tropical pause from late August to the middle of September, but don't throw a party yet.