How Tropical Storms Form Over Warm Ocean Waters. There are three major regions in the world where tropical storms commonly develop: the South China Sea, the Bay of Bengal, and the Gulf of Mexico.
A tropical storm gains energy from the moisture evaporating from the ocean surface, forming cloud structures and rainfall that are typically associated with storms. Therefore, the presence of a large body of water (sea, ocean) is a crucial condition.
The South China Sea, the Bay of Bengal, and the Gulf of Mexico are all located within the tropical zone, providing ample conditions for storm formation, particularly warm sea surface temperatures.
Within the tropical zone, storms are usually observed between latitudes 10° and 30°, avoiding proximity to the equator. This is because near the equator, the Coriolis force weakens the storm’s rotational movement.
Additionally, tropical storms often form near the Intertropical Convergence Zone (ITCZ), where the northeast and southeast trade winds converge. The ITCZ is a critical component as it triggers the movement of low-pressure air, which ultimately develops into a storm.
The South China Sea is one of the three regions in the world where tropical storms frequently form – (Image: AccuWeather).
“Most tropical storms form from areas of low pressure, spiraling upwards and breaking away from a vast low-pressure zone known as the monsoon trough. This formation process is different from storms in the Atlantic, which develop from tropical waves originating in West Africa,” explains meteorologist Dan Kottlowski from AccuWeather.com.
Tropical storms occur year-round in the northern South China Sea. However, the “storm season” – the period when storms are most prevalent in the South China Sea – typically begins from the transition to autumn (October) and continues into the first half of the northeast monsoon season (November-December).
Storms that occur during the southwest monsoon (March-September) usually form east of Luzon Island in the Philippines. Initially, they move towards Taiwan and then curve northeast towards southern Japan. These storms indirectly affect the South China Sea, causing high waves and strong winds.
As the year progresses, particularly from October to December, tropical storms primarily move westward, crossing the Philippines and entering the South China Sea. As the season advances, these storms tend to form further south.
How Are Storms in the South China Sea and Pacific Named?
Storms in the South China Sea and the Pacific are named by the Japan Meteorological Agency based on the database of the Tropical Cyclone Program under the World Meteorological Organization.
This list includes 140 names submitted by countries in the region such as China, Japan, Vietnam, Cambodia, and others.
The Philippines also contributes its own names; however, the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) will use local names whenever a storm enters its area of responsibility (PAR).
“Experts have a specific list of names to assign to storms. In rotation, one name will be withdrawn and replaced with another,” explains meteorologist Jim Andrews from AccuWeather.com.
