Fujiwhara Effect: When Storms Collide

August 21, 2020

Yet another reason why there's uncertainty in the storm tracks of TS Laura and TD #14. It's called the Fujiwhara effect-- named after the Japanese meterologist who first described it.

Here's what could happen if they get too close.

According to the National Weather Service, "When two hurricanes spinning in the same direction pass close enough to each other, they begin an intense dance around their common center. If one hurricane is a lot stronger than the other, the smaller one will orbit it and eventually come crashing into its vortex to be absorbed. Two storms closer in strength can gravitate towards each other until they reach a common point and merge, or merely spin each other around for a while before shooting off on their own paths. In rare occasions, the effect is additive when the hurricanes come together, resulting in one larger storm instead of two smaller ones."

For example, in 2005, TD Alpha was absorbed by Hurricane Wilma (see photo below).

Sooo, the question for Laura and TD 14 (presumably to be named Marco)... will they dance? Or will they merge? Or just keep a respectable distance from each other?

Fujiwhara Effect
This is an example of the "Fujiwhara effect" between a pair of low pressure systems off the U.S. East Coast on February 5, 2019. They rotate around each other and close the distance between them. Next week, it won't be as pronouced, but the two tropical systems in the Gulf could have some type of interaction involving this effect that could impact the tracks. But, it depends on the size and intensity of the tropical cyclones, and the distance between them. They won't "merge into a super hurricane" in this case as some suggest.
Posted by James Spann on Friday, August 21, 2020

Interesting trend in 18Z model output for Laura… stronger ridge north of the system; seems to be pulling toward the other tropical system (which should be Marco). Still lots of uncertainty here in environmental conditions over the Gulf/Deep South and interaction between the two pic.twitter.com/nqn2AVW0w8
— James Spann (@spann) August 21, 2020

Hurricane Wilma Makes Landfall In Florida

IN SPACE - OCTOBER 24: In this satellite image from NOAA (National Oceanic and Atmospheric Administration) taken at 9:45am EDT, Tropical Depression Alpha prepares to be absorbed by Hurricane Wilma, currently over southern Florida October 24, 2005. According to reports, Wilma made landfall south of Naples as a Category 3 storm.

(Photo by NOAA via Getty Images)