How the Hurricane Humberto draws the tropical storm Imelda far from the United States

How the Hurricane Humberto draws the tropical storm Imelda far from the United States

By Andrea Thompson Published by Jeanna Bryner

The southeast of the United States will probably avoid the worst effects of the Imelda tropical storm, all thanks to another tropical cyclone.

Imelda and Hurricane Humberto take place on the Caribbean of the Northeast, between the Bahamas and the Bermuda, for several days. Last Friday, the forecasts were very uncertain about the path of Imelda and the future force: the possibilities went from the storm which marked the earth in the Carolines, which would bring rains and torrential floods, which does not make earth in the United States, the latter now seems to be the probable scenario. Indeed, Imelda rejected in its development while Humberto quickly exploded in a major hurricane, which influenced how the two storms “feel” – essentially a flavor of what is called the Fujiwhara effect. (The coast will always be felt by the currents of Rip d’Imelda, however, and the storm could constitute a threat to the Bermuda because it takes a turn to the east in the coming days.)

Find out more: The science of hurricanes has a lot of jargon – here is what all this means

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The level of forecast uncertainty higher than usual can be explained in part by the fact that the Storms of the Atlantic generally do not form this close to each other. Tropical cyclones are influenced by the largest atmospheric environment, and the addition of another storm system makes this environment more complex. Meteorologists did not know exactly where the center of Imelda would be forged, which made it difficult to know how this center would interact with other characteristics of the atmosphere.

To get an idea of ​​the atmospheric image last Friday, it is useful to remember that the atmosphere is three -dimensional, with various areas with low or high pressure or winds of wind with various altitudes. In this case, there was a higher low pressure zone in the atmosphere above the southeast, a high pressure zone which is centered on the permanent plan roughly on the Bermuda, and the two storms-Humberto and what would become Imelda, then called new potential tropical cyclone. What was not clear is if Imelda would form quickly enough and in the right place to interact with this upper level, which would push him faster to the north and towards an American land. “Hurricane are governed by the surrounding wind flow, and faster [the storm] becomes stronger, the more it is influenced by the winds higher in the atmosphere, “explains Alan Gerard, a meteorologist from the retired national meteorological service, who directs the balanced weather.

But Imelda was very slow to organize in a complete tropical storm, so it slipped north slowly, leaving it to the ideal place to feel the attraction of Humberto. “Essentially what’s going on is: you have [westerly] Winds around Humberto du Cyclone, and Imelda is just caught in this area and follows behind, “says Gerard. *

This is a form of the Fujiwhara effect, explains Brian McNoldy, a hurricane researcher at the University of Miami. In 1921, Japanese meteorologist Sakuhei Fujiwhara theorized that two whirlwinds that were turning through liquid (which is exactly what tropical cyclones) could get closer to each other to begin to orbit a common central point. If such storms are still getting closer, they can possibly merge into one, which has happened with Hilary and Irwin hurricanes in the east of the Pacific in 2017.

Learn more: How to decode a hurricane forecast

Imelda and Humberto are not close enough for this to happen, but the Fujiwhara effect can take other forms once the distance between two storms is around 800 miles, and each can “feel” the other, says McNoldy. “The centers of Imelda and Humberto are now only 600 miles from each other, and their external circulation already communicate,” McNoldy wrote in an email to American scientist. “The model forecasts are still bringing them closer in the coming days.”

Humberto weakens the almost permanent ridge on the Bermuda and opens a path to pull Imelda behind. Essentially, “Imelda is taken in the wake of Humberto,” says Gerard.

Although this reduces risks in the United States, interaction could mean that Imada will constitute a direct threat to Bermuda more than Humberto; The latter will travel a few hundred kilometers north of the islands.

*Publisher’s note (09/29/25): This sentence was modified after publishing to correct the commentary by Alan Gerard on the West winds around Humberto.

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