Atlantic Hurricane Season Begins; El Nino May Reduce Activity

The Atlantic hurricane season has just begun. It runs from June 1 to November 30. Hurricane activity is highest in mid-September. During this time, warm ocean waters and atmospheric changes intensify tropical storms, primarily affecting the Caribbean and the eastern and Gulf coasts of the United States.

This year, meteorologists at the U.S. National Oceanic and Atmospheric Administration (NOAA) predict that the Atlantic hurricane season will be calmer than usual due to El Nino. They estimate a 55 percent chance of below-normal activity, a 35 percent chance of normal activity, and a 10 percent chance of above-normal activity.

What is El Nino and how does it affect hurricanes?

El Nino is the periodic warming of sea surface temperatures in the central and eastern tropical Pacific Ocean. It disrupts global wind and rainfall patterns, which can intensify floods, droughts, and heatwaves in various parts of the world. When El Nino is active, the world's average temperature also tends to increase slightly.

El Nino typically occurs at intervals of two to seven years and usually lasts for 9 to 12 months, although it can persist longer in some cases.

Its opposite is La Nina, in which the Pacific Ocean's temperature is colder than normal.

Both El Nino and La Nina are part of a larger climate cycle called ENSO (El Nino-Southern Oscillation).

Neutral Conditions

Under normal conditions, the trade winds blowing from east to west across the Pacific Ocean remain stable. These winds push warm surface water from the Americas towards Asia. Then, cold water from the depths of the ocean rises along the American coast, replacing the warm water.

Cold Phase: La Nina

La Nina is the opposite of El Nino. During this phase, the trade winds become even stronger than normal, pushing more warm water towards Asia. As a result, the surface temperature of the eastern Pacific Ocean becomes colder than average.

Warm Phase: El Nino

During El Nino, the trade winds weaken or even reverse direction. This allows warm water in the Pacific Ocean to return eastward, towards the Americas.

El Nino suppresses hurricane activity in the Atlantic region but increases storm activity in the Pacific region. La Nina, conversely, has the opposite effect, causing more and stronger hurricanes to form in the Atlantic region.

Why and how do tropical storms form?

Tropical storms form over warm ocean waters near the equator.

As warm air rises, an area of low pressure is created. As the air cools and descends, other warm air rises to take its place. This cycle generates strong winds and rain.

This process continues to strengthen, forming a tropical storm.

As the storm's rotation increases, a part called the 'eye' forms at its center. The eye of a storm is typically a calm, clear area with very low air pressure.

When wind speeds reach 63 kilometers per hour (39 miles per hour), it is called a tropical storm. When speeds reach 119 kilometers per hour (74 miles per hour), it becomes a hurricane, typhoon, or tropical cyclone.

Are hurricanes, cyclones, and typhoons the same?

Fundamentally, these three are the same type of powerful storm. The only difference is the location where they form.

Hurricane

Hurricanes form in the North Atlantic and Northeast Pacific Oceans. They primarily affect the East Coast of the United States, the Gulf of Mexico, and the Caribbean region. Hurricane strength is measured on a scale of 1 to 5. A Category 1 hurricane has winds of 119-153 km/h, while a Category 5 storm can have winds exceeding 252 km/h.

Cyclone

Cyclones form in the South Pacific and Indian Ocean regions. They can affect countries from Australia to Mozambique. The cyclone season typically runs from November to April.

Typhoon

Typhoons form in the Northwest Pacific Ocean and primarily affect the Philippines and Japan. The typhoon season is mainly from May to October, although they can form year-round. Extremely powerful typhoons are called 'super typhoons'.

The effects of El Nino vary in different parts of the world.

North Atlantic

During El Nino, hurricane activity in the Atlantic region decreases. In a normal season, there are 14 named storms, seven hurricanes, and three of those are major hurricanes.

Historical data shows that the number of hurricane days during El Nino decreases by about 60 percent, and the overall intensity of storms is also reduced.

Ken Graham, director of NOAA's National Weather Service, said, 'El Nino can suppress hurricane development in the Atlantic, but there is still uncertainty about how each season will develop.'

He warned, 'Just one storm can create extremely bad weather.' He urged residents in at-risk areas to be prepared.

Atlantic storms are among the deadliest and most expensive natural disasters in the world. In the United States alone, from 1980 to 2024, hurricanes have caused 7,211 deaths and approximately $1.55 trillion in economic damage. This includes devastating hurricanes such as Katrina (2005), Maria (2017), and Helene (2024).

Northeast Pacific (around Hawaii)

During El Nino, more storms tend to form around Hawaii. There is also a higher probability of many storms entering this region in the year following the end of El Nino.

Australia and South Pacific

During El Nino, fewer storms form off the coast of Australia. However, storms do not disappear entirely. Their formation areas shift eastward, concentrating in the South Pacific region near the International Date Line.

These changes are related to shifts in sea temperature and atmospheric conditions.

Asia and Northwest Pacific

Similar effects are observed in the Northwest Pacific region. While the total number of typhoons during El Nino may not change significantly, their formation locations do shift. Fewer typhoons form in the western part near Asia, while more form in the eastern part towards the International Date Line.

Regions with Little Change

No significant changes in storm activity are observed in the Southwest and North Indian Ocean regions.

How are storms named?

The practice of naming tropical storms began to facilitate warnings and communication. In the early days, storms were named arbitrarily, such as 'Hurricane Antje' after a damaged ship.

In the mid-20th century, storms began to be named after women. Later, meteorologists adopted a list of names in alphabetical order. Male names were included starting in 1979, and now male and female names are used alternately.

Hurricane names are taken from lists managed by the World Meteorological Organization (WMO). Six lists are rotated every six years. However, the names of extremely deadly or destructive storms are permanently retired. Katrina (2005), Sandy (2012), Irma, and Maria (2017) are examples of such names.