How could El Nino reshape tropical storms around the world this year?

El Nino tends to reduce hurricanes in the Atlantic while increasing storms in the Pacific Ocean.

The Atlantic hurricane season has just begun and runs from Monday to November 30 with storm activity peaking in mid-September.

During this period, warm ocean waters and atmospheric shifts feed and accelerate tropical storms and hurricanes that mainly threaten the Caribbean and the East and Gulf coasts of the United States.

This year, forecasters at the US National Oceanic and Atmospheric Administration (NOAA) predicted a quieter‑than‑usual Atlantic hurricane season, largely due to a phenomenon called El Nino. They see a 55 percent chance of below‑normal activity, a 35 percent chance of near‑normal and a 10 percent chance of above‑normal.

El Nino is the periodic warming of surface sea temperatures in the central and eastern tropical Pacific Ocean.

El Nino events typically occur every two to seven years and usually last nine to 12 months although some persist longer.

Its counterpart, La Nina, is the opposite, meaning cooler-than-normal Pacific temperatures.

Both are part of a larger climate pattern called ENSO (El Nino-Southern Oscillation), which has three phases, summarised in the graphic below:

Trade winds are steady, equatorial winds that blow from east to west across the Pacific Ocean. Under normal conditions, these winds push warm surface water away from the Americas towards Asia. As that warm water moves west, cold water rises from the ocean depths along the American coast to replace it.

La Nina is the opposite extreme of El Nino. Trade winds blow even stronger than usual, pushing more warm water towards Asia and dropping eastern Pacific surface sea temperatures below average.

During El Nino, these trade winds weaken or reverse, allowing the warm water in the Pacific to surge back east towards the Americas.

El Nino suppresses Atlantic hurricane activity while increasing Pacific storm activity whereas La Nina does the opposite, producing more and stronger Atlantic hurricanes.

Tropical storms form over warm ocean waters near the equator. Simply put, as this warm air rises, an area of lower air pressure is formed.

As the air cools down again, it is pushed aside by more warm air rising below it. This cycle causes strong winds and rain.

As this cycle gains momentum and strengthens, it creates a tropical storm.

As the storm system rotates faster, the centre of it, called an eye, forms.

The eye of the storm is very calm and clear and has very low air pressure as the intense rotation flings air outwards.

When winds reach speeds of 63 kilometres