Hurricanes usually cruise alone through the vast ocean, but sometimes they find themselves in close quarters, leading to unexpected interactions. This phenomenon is known as the Fujiwhara effect, where two storms get too close and start to influence each other’s strength and path.
This weekend, there’s a possibility that two storms will engage in this dance off the southeastern US coast. The first is Tropical Storm Humberto, which formed recently in the Caribbean. It’s expected to intensify into a hurricane soon. The second is a developing system in the northern Caribbean that might become Tropical Storm Imelda.
If the forecasts hold, these two storms could be within just a few hundred miles of each other early next week. That distance is key for the Fujiwhara effect to kick in, with storms of this size typically interacting when they get within 850 miles of one another, as noted by the National Oceanic and Atmospheric Administration.
Back in 1921, Japanese meteorologist Sakuhei Fujiwhara first described this phenomenon in detail. Imagine kids circling around a chair—when storms interact, they move in a similar way around a common point. The smaller the storms, the closer they need to be for this to happen, shrinking to around 350 miles for smaller systems.
When two storms are similarly matched, they often orbit each other for a while before eventually breaking apart. A great example of this was in 2017 when hurricanes Hilary and Irwin interacted until both dissipated. On the other hand, if one storm is much stronger, it may absorb the energy of the weaker one. This occurred in 2022 with Typhoon Hinnamnor, which ended up devouring a tropical depression, significantly impacting its path.
Interestingly, in rare cases, two smaller storms may merge to form a larger system, as discussed by the National Weather Service. This makes predicting outcomes a real challenge for meteorologists. Small shifts in storm strength or trajectory can drastically change the forecast’s accuracy.
As of now, we don’t know if Humberto and the potential Imelda will indeed affect each other. Close monitoring of forecasts will be essential as the weekend approaches.
