Tropical Cyclone Sean

Tropical Cyclone Sean has become a notable weather event affecting Western Australia as of January 2025. Initially forming on January 20, it intensified rapidly, reaching Category 4 strength before being downgraded to Category 3. The cyclone is expected to weaken further as it moves into cooler waters, with predictions suggesting it may lose tropical cyclone status by January 22, 2025. Significant rainfall has been recorded, particularly in Karratha, where a record 274 mm fell in just 24 hours, leading to local flooding.

Causes of Tropical Cyclones

recent-events/" target="_blank" rel="noopener">Tropical cyclones form under specific atmospheric and oceanic conditions. Key factors include:

• Warm Sea Surface Temperatures: Cyclones require sea temperatures above 27 °C for development.
• Coriolis Force: This force facilitates the rotation necessary for cyclone formation
• Low-Pressure Area: A weak low-pressure system is essential to initiate cyclone activity.
• Vertical Wind Shear: Minimal wind speed variations support cyclone stability and growth.

Formation of Tropical Cyclone Sean

Tropical Cyclone Sean began as a tropical disturbance. It quickly intensified over warm waters. Key aspects of its structure include:

• Eye and Eyewall: The eye has calm weather, while the eyewall contains the strongest winds and heaviest rainfall.
• Updrafts and Moisture: Rising moist air forms clouds, which are crucial for storm development.

Effects of Tropical Cyclone Sean

The cyclone has had effects on the affected regions:

• Heavy Rainfall: Karratha experienced its highest daily rainfall, causing localised flooding.
• Flooding Risks: Emergency alerts were issued due to potential flash flooding along the Pilbara Coast.
• Infrastructure Impact: Floodwaters have affected roads and homes, although damage has been minimal since the cyclone did not make landfall directly.

Impact on Communities

The cyclone has disrupted daily life, particularly in towns like Karratha and Exmouth:

• Flooding and Disruptions: Emergency services responded to various incidents, including water rescues and power outages.
• Infrastructure Challenges: Some roads were closed due to flooding, though the North West Coastal Highway remained open with caution advised.

Current Updates and Future Outlook

As of January 21, 2025, Tropical Cyclone Sean has been downgraded to Category 3. It is approximately 400 km offshore and poses no direct threat to the mainland. No additional cyclones are forecasted in the immediate future, suggesting stabilisation in weather conditions after Sean’s passage.

Questions for UPSC:

1. Critically analyse the factors contributing to the formation of tropical cyclones in oceanic regions.
2. Explain the structure of a tropical cyclone and its significance in weather prediction.
3. What are the implications of heavy rainfall on infrastructure during tropical cyclones? Discuss with suitable examples.
4. What is the role of emergency services during natural disasters like tropical cyclones? How can their effectiveness be improved?

Answer Hints:

1. Critically analyse the factors contributing to the formation of tropical cyclones in oceanic regions.

1. Warm Sea Surface Temperatures – Cyclones form over waters exceeding 27 °C, providing heat and moisture.
2. Coriolis Force – This force is essential for cyclone rotation, influencing storm organization.
3. Low-Pressure Area – A weak low-pressure system is necessary for initiating cyclone development.
4. Vertical Wind Shear – Minimal variations in wind speed enhance cyclone stability and growth.
5. Moisture Availability – Abundant moisture in the atmosphere fuels storm intensification.

2. Explain the structure of a tropical cyclone and its significance in weather prediction.

1. Eye – The calm center of the cyclone, characterized by low pressure.
2. Eyewall – Surrounds the eye, containing the strongest winds and heaviest rainfall.
3. Rainbands – These spiral outward from the eyewall, bringing rain and wind to surrounding areas.
4. Significance – About the structure helps predict storm intensity and potential impacts.
5. Satellite Imagery – Used to monitor cyclone structure and track movement for forecasting.

3. What are the implications of heavy rainfall on infrastructure during tropical cyclones? Discuss with suitable examples.

1. Flooding – Heavy rainfall can overwhelm drainage systems, leading to localized flooding, as seen in Karratha.
2. Road Damage – Floodwaters can erode roads and bridges, making them impassable.
3. Power Outages – Flooding can damage power lines and substations, disrupting electricity supply.
4. Emergency Services – Increased demand for rescue operations and infrastructure repairs during flooding.
5. Long-term Impact – Prolonged flooding can lead to structural damage and economic losses for communities.

4. What is the role of emergency services during natural disasters like tropical cyclones? How can their effectiveness be improved?

1. Disaster Response – Emergency services coordinate evacuations, rescue operations, and provide medical assistance.
2. Public Communication – They issue alerts and updates to inform residents about safety measures and risks.
3. Infrastructure Assessment – Assessing damage and prioritizing repairs to restore essential services post-disaster.
4. Training and Preparedness – Regular drills and training can enhance readiness for future events.
5. Community Engagement – Involving local communities in preparedness plans can improve response effectiveness.