Tropical Storm Humberto could tangle with another developing storm, with high stakes for the US East Coast

By CNN Meteorologist Briana Waxman

(CNN) — Tropical Storm Humberto is spinning in the central Atlantic, but the bigger question for the United States is what’s brewing behind it.

A disturbance moving through the northern Caribbean — already drenching Puerto Rico, the Virgin Islands and Hispaniola — has a high chance of becoming the next named storm by this weekend.

What makes the forecast especially complicated is how this disturbance might interact with Humberto. If it stays weak, Humberto could tug it harmlessly out to sea. But if it strengthens over the very warm Caribbean water, it could resist Humberto’s pull and take a path that threatens the East Coast. How strong Humberto gets, how large it grows, and how close the two storms come to each other will all shape the outcome.

Multiple Hurricane Hunter aircraft, operated by the National Oceanic and Atmospheric Administration, will be flying crucial missions in and around these storm clusters frequently over the next two days. Their goal is to collect as much data as possible to feed into the computer models that produce weather forecasts. The more these models know about the state of the atmosphere right now, the better they can predict what will happen.

The disturbance west of Humberto, known for now as Invest 94L, is in a favorable environment for development, fueled by very warm Caribbean water. Forecast models show it moving northward toward the Bahamas this weekend, right into the same neighborhood as Humberto. That sets up a complex scenario where the size, strength and timing of both storms will decide whether the East Coast gets a brush, a direct landfall, or a miss.

If 94L stays weak, Humberto’s pull could be enough to steer it away from the United States, keeping any serious impacts offshore. If the disturbance strengthens into a tropical depression or tropical storm, though, it becomes harder for Humberto to influence. A stronger storm has more control over its own track, and that could leave the East Coast more exposed, depending on how the upper level weather pattern over the eastern US sets up.

There’s also the chance the two storms get close enough to interact. When that happens, they can do-si-do around a common point in what’s known as the Fujiwhara effect. Time will tell if Humberto will be swinging its partner round and round, closer to land, or flinging it harmlessly out to sea.

As if all these variables weren’t enough, the broader weather pattern adds yet another layer of uncertainty. A trough of low pressure over the eastern US will play a major role in steering any tropical systems that enter its sphere of influence. If Humberto drifts east and the trough dominates, the disturbance could be drawn into the Southeast coast. If Humberto grows larger and stronger, it may keep the disturbance offshore.

In the meantime, Invest 94L could produce flooding rain in Puerto Rico and the Virgin Islands through late Thursday. Some areas could get up to 6 inches, bringing the risk of flash flooding and landslides in areas with steep terrain.

For now, the outcome of this story is far from settled. The only thing forecasters can promise this week is that the forecast itself will keep changing.

The-CNN-Wire
™ & © 2025 Cable News Network, Inc., a Warner Bros. Discovery Company. All rights reserved.