IAS Gyan

Daily News Analysis


24th August, 2023 Geography

Disclaimer: Copyright infringement not intended.


The occurrence and implications of the "Fujiwhara effect."


  • The United States West Coast has experienced unusual weather phenomena recently, including Hurricane Hilary.
  • The National Hurricane Centre issued its first tropical storm watch for parts of Southern California due to this sub-tropical storm. Unusual weather events, like the "Fujiwhara effect," have been observed in the region.

Atmospheric Rivers and Fujiwhara Effect

  • California witnessed an unusually wet winter with "atmospheric river" storms, carrying dense moisture in the atmosphere.
  • The "Fujiwhara effect" occurs when two hurricanes or cyclones spin in the same direction and interact closely.
  • These cyclones engage in an intense dance around a common center, with outcomes depending on their relative strengths.
  • If one cyclone is stronger, it absorbs the weaker one. Similar-strength cyclones may merge or spin around each other before separating.
  • Rarely, intense cyclones merging can form a mega cyclone with destructive potential.
  • The phenomenon was first identified by Japanese meteorologist Sakuhei Fujiwhara in 1921 and observed in 1964 over the Pacific Ocean.

Outcomes Based on Cyclone Strength

Weaker Cyclone Absorption

  • If one cyclone is significantly weaker than the other, it can get drawn into the circulation of the stronger cyclone.
  • Eventually, the weaker cyclone is absorbed, and their individual identities are lost.

Similar-Strength Cyclones

  • Cyclones of comparable strengths may either merge to form a larger cyclone or engage in a complex rotational dance.
  • Their interaction results in unpredictable movements as they gravitate towards each other and exchange energy.

Intense Cyclone Merging

  • In rare cases, two intense cyclones can merge, leading to the formation of a mega cyclone with heightened destructive potential.
  • This merging amplifies their combined energy and can have severe consequences for coastal regions.

Historical Context and Discovery

  • Identified by Japanese meteorologist Sakuhei Fujiwhara in 1921.
  • The effect was first mentioned in Fujiwhara's 1921 paper.
  • The phenomenon was observed over the western Pacific Ocean when Typhoons Marie and Kathy merged in 1964.

Impact and Observations

  • In March 2023, the Bay Area and Southern California faced powerful winds and damage due to the Fujiwhara effect.
  • Typhoon Hinnamnor and tropical storm Gardo exhibited the Fujiwhara effect, leading to casualties in South Korea.
  • Hurricane scientist David Longshore noted that the effect might intensify the primary circulation of a system and make cyclonic systems harder to predict.

Relation to Climate Change

  • Experts link the increasing frequency of the Fujiwhara effect to global warming and rising ocean temperatures.
  • Ravi Shankar Pandey's research shows a 35% increase in typhoon strength in Taiwan between 1977 and 2016 due to rising sea surface temperatures.


Q) Discuss the 'Fujiwhara Effect' in the context of cyclonic interactions and its implications for weather patterns and climate change. (150 words)