What is Fujiwhara effect/ Explain its impact on movement and intensity of tropical cyclone

What is Fujiwhara effect/ Explain its impact on movement and intensity of tropical cyclone

22
Aug

What is Fujiwhara effect/ Explain its impact  on movement and intensity of tropical cyclone

The Fujiwhara effect (often spelled Fujiwhara interaction) is a meteorological phenomenon that occurs when two nearby low-pressure atmospheric storms—typically tropical cyclones, typhoons, or hurricanes—approach each other and begin to interact.

First identified in 1921 by Japanese meteorologist Dr. Sakuhei Fujiwhara, the effect kicks in when two tropical storms come within roughly 1,400 kilometers (870 miles) of each other. Instead of following their individual projected tracks, the two storms begin orbiting around a shared central point between them

Effect on Movement (Track & Trajectory)

When the Fujiwhara interaction triggers, the cyclones abandon their original background tracks dictated by trade winds and high-pressure ridges

• Cyclonic Orbit: The storms begin orbiting counter-clockwise around a shared central point (in the Northern Hemisphere).
• Deflection & Erratic Path: Instead of straight, predictable paths, the storms execute loop-de-loops, sharp right-angle turns, or s-curves, making track forecasting notoriously difficult.
• Acceleration & Slingshotting: The mutual circulation forces can accelerate one storm forward rapidly or “slingshot” it far out to sea.
• Stalling: The competing wind forces can lock two storms in place, causing them to hover stationary over one region for days, leading to extreme catastrophic flooding.

Effect on Intensity (Strength & Wind Speeds)

Unlike two fires combining to form a larger fire, two interacting cyclones rarely intensify simultaneously. The Fujiwhara interaction usually impacts intensity in specific, asymmetrical ways:

• Vertical Wind Shear (Weakening): The upper-level outflow from the stronger storm disrupts the delicate warm-core structure of the weaker storm. This strong wind shear strips away its thunderstorms, causing the weaker storm to rapidly disintegrate.
• Moisture Robbery (Starvation): The dominant storm draws surrounding warm, moist air into its own circulation, cutting off the latent heat source that fuels the smaller cyclone.
• Merger (Size Expansion vs. Wind Peak): If a smaller storm is absorbed by a larger storm, the resulting combined system becomes physically larger with a vast cloud field, but its peak wind intensity rarely increases. Instead, the kinetic energy distributes over a broader geographical area.
• Mutual Destruction: In rare cases where two equally powerful storms collide aggressively, high shear and disrupted inflow cause both storms to weaken simultaneously before separating or dissolving.