Fujiwhara Effect
Why in news?
Recent forecasts from November 2025 highlight a potential Fujiwhara interaction between two cyclonic storms in the Bay of Bengal, one forming from the Andaman Sea and another from the Comorin area.
About
- Fujiwhara Effect is a meteorological phenomenon where two nearby tropical cyclones interact by rotating around a common center due to their low-pressure circulations.​
- Named after Japanese meteorologist Sakuhei Fujiwhara, who described it in a 1921 paper.​
- Occurs when cyclones are within 1,400 km (tropical) or 2,000 km (extratropical) of each other.​
- Elastic Interaction: Storms deflect each other without merging; most common.​
- Capture: Weaker storm orbits and is absorbed by stronger one.​
- Partial Merger: Smaller storm merges into larger one.​
- Complete Merger: Similar-strength storms fully combine into one intensified cyclone.​
- Straining Out: Weaker storm dissipates completely.​
- Alters tracks, intensity, and rainfall; increases unpredictability.​
- Can cause rapid intensification, stalling, and higher disaster risks like surges.​
- Complicates forecasts due to unique interactions.​
- 1964: Typhoons Marie and Kathy (first observed merger).​
- 2017: Hurricanes Hilary and Irwin (East Pacific).​
- 2009: Typhoon Parma and Melor.​
- 2025: Hurricanes Imelda and Humberto (Atlantic).​
