23/09/2025
TUESDAY TROPICS UPDATE - WITH Bryan Norcross DISTURBANCES TO WATCH FOR FLORIDA, THE SOUTHEAST U.S., AND BERMUDA
As Hurricane Gabrielle accelerates away from Bermuda, our attention turns to two tropical disturbances (tagged Invest 93l and 94L) east of the Caribbean. Both have a good chance of developing late in the week or over the weekend. Systems designated “invests” are just disturbances, but they have sufficient organization that the NHC can run specialized computer models and analyses on them.
RED DISTURBANCE – INVEST 93L
Invest 93L is a large disturbance embedded in a cloud of dry air and Saharan dust, which is slowing its development. There is a strong consensus in the various computer forecasts that the system will break free of the dust, however, as it tracks north in the general direction of Bermuda. The National Hurricane Center has followed suit and has the odds of development in the very high range.
An unusually high percentage of the potential tracks show the system developing into a large, strong hurricane in the general vicinity of Bermuda in about a week. Everybody on the island should stay in close touch with the forecasts once the system develops.
The next two names on the list are Humberto and Imelda. Unless something unexpected happens with the orange disturbance (Invest 94L), and it suddenly develops, the red disturbance (93L) will become Tropical Storm Humberto in a few days.
ORANGE DISTURBANCE – INVEST 94L
Invest 94L is finally breaking free of the hostile upper winds emanating from Hurricane Gabrielle. The weather pattern is becoming increasingly conducive to the system organizing.
It’s moving over the northeastern Caribbean islands, however, and will reach the Virgin Islands and Puerto Rico tomorrow. It's unlikely to organize into more than a gusty moisture surge over the islands, but everybody should stay in touch with the latest updates.
Flooding has been a concern on Puerto Rico with recent heavy rain, which will increase with this additional deep tropical moisture. El Yunque Peak, the 3,500-foot mountain in the center of the island, will be a deterrent to the system developing quickly, but will also enhance the rainfall on its windward slopes.
When the disturbance arrives over or near the southeastern Bahamas about Thursday, there is a reasonable consensus in the computer forecasts that the system will begin to organize. The National Hurricane Center gives 94L a medium chance of developing into at least a tropical depression.
Once the system is over or near the Bahamas in a few days, it is forecast to slow down, and things get tricky. Most computer forecasts show the depression or storm tracking north off the Florida coast in the general direction of North Carolina. But enough forecasts curl it toward the coast into Florida, Georgia, or South Carolina, that everyone is going to have to watch it closely.
The weather pattern is forecast to be marginal for significant strengthening, but any storm tracking over warm, deep water of the Gulf Stream has plenty of fuel to intensify.
The time frame for potential impact with the coast would be late in the weekend or early next week.
A fundamental rule of forecasting is that forecasts for disorganized, just-organizing, or slow-moving systems are subject to larger than normal errors and subject to change. This system looks to check two of those boxes.
For now, there's nothing to do but watch for developments.
The exclusive FOX Weather Tropical Threat analysis, which combines the forecast arrays from the European, U.S. GFS, and Google DeepMind AI models, shows the relatively high-certainty path of 93L in the general direction of Bermuda, and the less-certain development zone of 94L over the Bahamas and along the east coast of Florida and the Southeast.
The color simply tells you the areas with the highest likelihood of at least a tropical depression forming or tracking.
HURRICANE GABRIELLE
On its current forecast track, Hurricane Gabrielle will be in the general vicinity of the Azores late Thursday or Friday. Residents there should stay in close touch with the latest forecasts and local instructions.
Gabrielle is currently a powerful Category 4 storm but is forecast to start weakening tomorrow under more hostile upper winds and over cooler water. But it is expected to still be a formidable storm when it arrives near the Azores. The remnants are forecast to be near northwestern Spain and Portugal early next week.
