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What El Niño and a warming Atlantic Ocean could mean for the 2023 hurricane season




The U.S. National Oceanic and Atmospheric Administration (NOAA) is projecting 12 to 17 named storms — five to nine of which will become hurricanes — in its Atlantic hurricane outlook for the upcoming 2023 season released Thursday.

This would be considered an average season in the Atlantic basin, however there’s a little more uncertainty than usual heading into the coming months due to two competing factors which could swing the season one way or the other.

Satellite image of Post-Tropical Storm Fiona over the Maritimes on September 24 2022.
Satellite image of post-tropical storm Fiona over the Maritimes on Sept. 24, 2022. (NASA)

NOAA is forecasting a modest 40 per cent chance of a normal year, and a 30 per cent chance of both an above-normal and below-normal season. 

The changing wind patterns caused by El Niño and La Niña weather events have a strong influence on hurricane activity in the Atlantic even though the events occur in the eastern Pacific Ocean, thousands of miles away from any developing hurricanes.

Following a long La Niña event, there’s good consensus that an El Niño is developing in the eastern Pacific. However, large questions remain about how strong the event will be by the time we get into the key months of August, September and October.

NOAA is projecting a 40% chance of a near average hurricane season.
NOAA is projecting a 40 per cent chance of a near average hurricane season. (Ryan Snoddon/CBC)

When a cooler-water El Niño event is underway in the Pacific, stronger wind shear occurs over the Caribbean and tropical Atlantic Ocean. This wind shear can suppress the development and growth of tropical storms and hurricanes.

A warm Atlantic Ocean

On the other hand, we have very warm waters in tropical areas of the Atlantic Ocean that are already running warmer than average in May. Sea surface temperatures are one to three degrees higher than average from the Cape Verde region to the Caribbean and into the Gulf of Mexico.

There are two conflicting factors for the upcoming season. Warmer than average Atlantic ocean temps and a developing El Nino in the eastern Pacific.
There are two conflicting factors for the upcoming season: warmer than average Atlantic Ocean temperatures and a developing El Niño in the eastern Pacific. (Ryan Snoddon/CBC)

Warm ocean water is the fuel that tropical systems need to develop and grow stronger, so a warmer than normal Atlantic could be a big factor in the upcoming season, especially if the El Niño event is a bit sluggish to start. 

Another factor at play will be the West African monsoon season, which is expected to be active.

Large areas of thunderstorms that roll off the coast of Africa are the seeds for tropical systems, especially when they roll into ocean water that is running warmer than normal. 

Sea surface temperatures are running warmer than average throughout the tropical Atlantic ocean
Sea surface temperatures are running warmer than average throughout the tropical Atlantic Ocean, indicated by areas coloured orange, red and brown. (WeatherBell Analytics)

It only takes one storm

It’s important to remember that destructive storms can occur in any hurricane season, even one with fewer storms overall.

While we can’t ultimately tell where and when these storms will occur, we do know that the month of September is historically the most active.

Hurricane peaks in September in the Atlantic ocean.
Hurricane season peaks in September in the Atlantic Ocean. (NOAA)

With damage from post-tropical storms Fiona and Dorian fresh on our minds here in Atlantic Canada, we really don’t need a reminder of how destructive these storms can be.

The hurricane outlook is a good reminder that the time to be ready and prepared is coming quickly.


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