Following El Niño's Influence on the Atlantic Hurricane Season

It’s full steam ahead for El Niño in the Pacific, but so far the Atlantic hasn’t taken notice

The abnormal warming of the waters in the central and eastern Pacific around the equator – an event widely known as El Niño – shows no sign of pulling back.

Waters this week across the El Niño monitoring region of the Pacific are running over a degree Celsius (1.8 degrees Fahrenheit) above the long-term averages, which may not sound impressive, but it’s the type of warmth that signals a growing ocean fever.

The threshold for El Niño is set at 0.5 degrees Celsius above average, so when water temperature anomalies approach 1.0 to 1.5 degrees Celsius, El Niño is maturing. This is the case this summer. Yet despite rivaling the pace of the 2015 and 1997 El Niño events – two of the strongest on record – we’ve yet to see the upside of El Niño show face in the Atlantic, where it typically deters storm activity by way of storm-busting wind shear, especially across the Caribbean and western Atlantic.

Wind shear anomaly pattern for August, September, and October during El Niño years. Note the warm colors indicating stronger than average wind shear through the Caribbean and Main Development Region or MDR of the Atlantic.

This June not only didn’t see much wind shear across these areas of the tropical Atlantic, it observed the lowest shear through the Caribbean since 2010.

June 2023 wind shear anomalies with much weaker than average wind shear over the Caribbean and western Main Development Region or MDR of the Atlantic.

That’s hardly the type of development we’d expect during a rip-roaring El Niño. Or is it?

El Niño is most commonly defined by the deviation from typical ocean conditions, but the atmosphere doesn’t immediately respond to these changes. It takes time. Strong El Niño years like 1982 and 1997 also recorded average to below average June wind shear despite ultimately ending as two of the least active hurricane seasons of the past 40 years.

It’s not until July that we traditionally begin to see El Niño’s influence on the Atlantic. We’ll be watching this bellwether shear across the Caribbean and Main Development Region this month, as stronger shear can portend less peak season activity (while less shear can signal greater peak season activity). This year is of particular interest since the unprecedented Atlantic warmth may serve to counteract El Niño’s typical Atlantic restraint.

As we discussed in Monday’s newsletter, at least for now wind shear will be ramping up and shutting things down across the Atlantic in the week ahead.

It’s too soon yet to say whether the heightened shear forecast are El Niño’s fingerprints, but its onset does give some credence to a changes afoot over the Atlantic. Of course, no matter how the season progresses or how many storms form, it only takes one bad hurricane in South Florida to make for a bad year.

For today and through the extended holiday week, everyone along the glistening shores of the U.S. can enjoy the fireworks and 4^th of July celebrations without worries of tropical disruptions from Mother Nature. Have a wonderful holiday!