TAMPA, Fla. (WFLA) — Weather nerds around the world are watching topics like a hawk this weekend, Tropical Storm Humberto and the disturbance expected to develop into Imelda may be close enough together to experience the Fujiwhara effect.
It’s pretty rare to see, since it is difficult for storms to form close enough together to interact, but when they do, it looks like a little dance around each other.
As explained by the NWS/NOAA, the Fujiwhara effect occurs when two hurricanes spinning in the same direction (counterclockwise for the Northern Hemisphere) get close enough together, they begin to dance around each a center foint between them, a fulcrum point at which they rotate around.
The evolution of the storms as they experience the Fujiwhara effect depends on their strength. If they are similar in strength, they tend to pull each other around in the dance until they merge, or shoot off in their own directions. If one storm is significantly stronger than the other, the weaker system will orbit the stronger one until it is absorbed by the stronger system.
Humberto would most likely be the stronger system if and when the two areas experience the Fujiwhara effect, so what is now Invest 94L, possibly developing into Imelda, would be pulled towards Humberto. Some long term forecast models (especially the model runs on Wednesday) show the Fujiwhara effect by Humberto pulling the weaker system away from the Carolinas and out into the open Atlantic.
Today, most forecast models have shifted away from that possibility and have Invest 94L pushing into the Carolinas, not being pulled by Humberto and the Fujiwhara effect, but we may see the models shift back in that direction.
Model uncertainty is very high before a system forms. Once a system forms and you have a clear center of rotation for all models to use, forecast certainty grows.