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.
Interaction Types
- 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.
Impacts
- Alters tracks, intensity, and rainfall; increases unpredictability.
- Can cause rapid intensification, stalling, and higher disaster risks like surges.
- Complicates forecasts due to unique interactions.
Examples
- 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).
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