The Fujiwhara effect

Has to be one of my favorite weather terms and yes I have a list of favorite weather terms. This term is getting a lot of traction at the moment in both the meteorological world and outside of it. Now being a big hurricane geek I have known about this term for a long time. But for those that don’t or want to know more then hopefully this blog post will enlighten you.

So what is the The Fujiwhara effect?

From Wikipedia

The Fujiwhara effect, sometimes referred to as the Fujiwara effect, Fujiw(h)ara interaction or binary interaction, is a phenomenon that occurs when two nearby cyclonic vortices orbit each other and close the distance between the circulations of their corresponding low-pressure areas.

It is named after Japanese meteorologist Sakuhei Fujiwhara who first coined the phrase in 1921 to describe water vortices.

https://en.wikipedia.org/wiki/Fujiwhara_effect#:~:text=The%20Fujiwhara%20effect%2C%20sometimes%20referred,their%20corresponding%20low%2Dpressure%20areas.

So this can occur between tropical cyclones in any part of the globe. This is a prime example in the image below.

Typhoon Parma (left) and Melor (right) interacting with each other in the Philippine Sea on October 6, 2009.

NASA image courtesy the MODIS Rapid Response Team at NASA GSFC. Caption by Holli Riebeek. – http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=40615(direct link)

So why is sudden increase in media attention?

Because in the Atlantic we have two named Tropical Systems Marco and Laura and there is a chance of some interaction of these systems into early next week as the both head into the Gulf of Mexico. Unfortunately this is resulted in a lot of clickbait headlines and pronouncements of the two storms merging into one mega storm which would be so “2020”! Please bear with me a moment whilst I facepalm and sigh loudly. This just wouldn’t happen. Some tweets below show examples of what can happen.

What is known there is a lot of uncertainty about the track and intensity of these two systems. To get two named systems in the Gulf of Mexico at the same time is unusual

Please refer to the National Hurricane Centre website for the very latest on the track of these two systems

https://www.nhc.noaa.gov/

So what are the other occurrences of the The Fujiwhara effect?

Dr Kim Wood on twitter posted an excellent thread on this earlier today.

Which can be found here https://twitter.com/DrKimWood

Hopefully helps to explain the Fujiwhara effect. Any feedback is always welcome!

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