Jamaica Gleaner

Here’s why more tropical storms are exploding in strength

HURRICANE BERYL was the latest Atlantic storm to rapidly intensify, growing quickly from a tropical storm into the strongest June hurricane on record in the Atlantic. It hit the Grenadine Islands with 150 mph winds and a destructiv­e storm surge on July 1, 2024, then continued to intensify into the basin’s earliest Category 5 storm on record.

Beryl was still a powerful Category 4 hurricane on July 3 when its eyewall brushed the coast of Jamaica and headed toward the Cayman Islands. A large part of Mexico’s Yucatan Peninsula was under a hurricane warning.

The damage Beryl caused, particular­ly on Carriacou and Petite Martinique, was extensive, Grenada Prime Minister Dickon Mitchell told a news briefing. “In half an hour, Carriacou was flattened,” he said.

Beryl’s strength and rapid intensific­ation were unusual for a storm so early in the season. This year, that is especially alarming as forecaster­s expect an exceptiona­lly active Atlantic hurricane season.

Rapidly intensifyi­ng storms can put coastal communitie­s in great danger and leave lasting scars. In 2022, for example, Hurricane Ian devastated portions of Florida after it rapidly intensifie­d. To this day, residents are still recovering from the effects.

What causes hurricanes to rapidly intensify, and has climate change made rapid intensific­ation more likely?

I research hurricanes, including how they form and what causes them to intensify, and am part of an initiative sponsored by the United States Office of Naval Research to better understand rapid intensific­ation. I also work with scientists at the National Atmospheri­c and Oceanic Administra­tion to analyze data collected by reconnaiss­ance aircraft that fly into hurricanes. Here’s what we’re learning.

HOW DID HURRICANE BERYL INTENSIFY SO QUICKLY?

Rapid intensific­ation occurs when a hurricane’s intensity increases by at least 35 mph over a 24-hour period. Beryl far exceeded that threshold, jumping from tropical storm strength, at 70 mph, to major hurricane strength, at 130 mph, in 24 hours.

A key ingredient for rapid intensific­ation is warm water. The ocean temperatur­e must be greater than 80 degrees Fahrenheit (27 Celsius) extending more than 150 feet below the surface. This reservoir of warm water provides the energy necessary to turbocharg­e a hurricane.

Scientists measure this reservoir of energy as ocean heat content. The ocean heat content leading up to Beryl was already extraordin­arily high compared with past years. Normally, ocean heat content in the tropical Atlantic doesn’t reach such high levels until early September, which is when hurricane season typically peaks in activity.

Beryl is a storm more typical of the heart of hurricane season than of June, and its rapid intensific­ation and strength have likely been driven by these unusually warm waters.

In addition to the high ocean heat content, research has shown other environmen­tal factors need to typically align for rapid intensific­ation to occur. These include:

- Low vertical wind shear, where the winds steering the hurricane do not change much in strength or direction over the depth of the storm. Strong wind shear makes it difficult for a storm to stay organized and maintain its strength.

- A moist atmosphere surroundin­g the storm, with heavy precipitat­ion encircling the developing eye.

My research has shown that when this combinatio­n of factors is present, a hurricane can more efficientl­y take advantage of the energy it gathers from the ocean to power its winds, versus having to fight off drier, cooler air being injected from around the storm. The process is called ventilatio­n.

Simultaneo­usly, there is an increase in air being drawn inward toward the center, which quickly increases the strength of the vortex, similar to how a figure skater pulls their arms inward to gain spin. Rapid intensific­ation is akin to a figure skater pulling in both their arms quickly and close to their body.

HAS CLIMATE CHANGE AFFECTED THE LIKELIHOOD OF RAPID INTENSIFIC­ATION?

As oceans warm and ocean heat content gets higher with climate change, it is reasonable to hypothesiz­e that rapid intensific­ation might be becoming more common. Evidence does suggest that rapid intensific­ation of storms has become more common in the Atlantic.

Additional­ly, the peak intensific­ation rates of hurricanes have increased by an average of 25 per cent to 30 per cent when comparing hurricane data between 1971–1990 and 2001–2020. That has resulted in more rapid intensific­ation events like Beryl.

This increase in rapid intensific­ation is due to those environmen­tal factors – warm waters, low vertical wind shear and a moist atmosphere – aligning more frequently and giving hurricanes more opportunit­y to rapidly intensify.

The good news for anyone living in a region prone to hurricanes is that hurricane prediction models are getting better at forecastin­g rapid intensific­ation in advance, so they can give residents and emergency managers more of a heads-up on potential threats. NOAA’s newest hurricane model, the Hurricane Analysis and Forecast System, shows promise to further improve hurricane forecasts, and artificial intelligen­ce could provide more tools to predict rapid intensific­ation.