# Fujiwhara Effect of Tropical Cyclones Seroja & Odette

**URL:** <https://forum.ecmwf.int/t/fujiwhara-effect-of-tropical-cyclones-seroja-odette/12359>\
**Category:** IFS\
**Created:** [10 May 2021 17:59 UTC](https://forum.ecmwf.int/t/fujiwhara-effect-of-tropical-cyclones-seroja-odette/12359 "2021-05-10T17:59:55Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Rebecca\_Emerton](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/r/e19b73/32.png) [@Rebecca\_Emerton](https://forum.ecmwf.int/u/Rebecca_Emerton)\
**Post date:** [10 May 2021 17:59 UTC](https://forum.ecmwf.int/t/fujiwhara-effect-of-tropical-cyclones-seroja-odette/12359/1 "2021-05-10T17:59:55Z")

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On 10th April, tropical cyclones Seroja and Odette merged together - a rare phenomenon called the Fujiwhara Effect, which presents a significant challenge in forecasting track and intensity of the tropical cyclones.&nbsp;

Typically, the stronger storm absorbs the weaker storm, and in this case Odette was absorbed by the stronger Seroja, before Seroja made landfall in Australia on 11th April as a category 3 tropical cyclone. The merging of the two cyclones was predicted in ECMWF's forecasts from ~3 days ahead.&nbsp;

Satellite images from NASA's Worldview show the storm(s) on 9th, 10th and 11th April as they merge and make landfall: