Hurricane Helene has joined Hurricane Debby, Hurricane Francine, and Potential Tropical Cyclone Eight1 in an unusual string of four rapidly intensifying storms in a row during the 2024 Atlantic hurricane season. This concerning trend of storms quickly gaining strength is giving people less time to prepare and catching many off guard.
So why are Atlantic hurricanes developing so fast this year, and what can we expect for the rest of the season?
Understanding Rapid Intensification
Rapid intensification is defined as a tropical storm or hurricane gaining at least 35 mph in maximum sustained winds within 24 hours. It’s one of the most challenging aspects of hurricane forecasting, as it makes predicting a storm’s peak intensity and strength at landfall very difficult.
Several key ingredients are needed for rapid intensification to occur:
- Warm ocean water of at least 80°F (26.5°C)
- Low wind shear (change in wind speed/direction with height)
- Abundant moisture in the atmosphere
When these conditions align, they provide the perfect environment for tropical storms to quickly strengthen into major hurricanes. However, not every storm will undergo rapid intensification, even when conditions are favorable.
Why 2024 is Ripe for Rapidly Intensifying Storms
The 2024 Atlantic hurricane season is shaping up to be extremely active, with AccuWeather predicting 20-25 named storms, 8-12 hurricanes, and 4-7 major hurricanes. (ref) This is well above the average of 14 named storms, 7 hurricanes, and 3 major hurricanes.
There are a few key reasons why meteorologists are expecting so many rapidly intensifying storms this year:
Unusually Warm Ocean Waters
Sea surface temperatures across the Atlantic hurricane basin are running 2.5-4°F above historical averages, even higher than the already warm 2023 season.
More importantly, there are large areas where this extremely warm water extends hundreds of feet deep, providing ample oceanic heat content (OHC) to fuel strengthening storms.
High OHC acts like “rocket fuel” for hurricanes, helping them intensify very quickly. Areas of the Caribbean have 80°F water reaching depths of 600 feet, which is more typical of August than early in the season.
These unusually warm waters are a prime concern for rapid intensification this year.
Favorable Atmospheric Conditions
In addition to the warm ocean, atmospheric conditions are also very favorable for hurricane development in 2024. La Niña, the periodic cooling of the equatorial eastern Pacific, is expected to redevelop later this summer or fall.
La Niña reduces wind shear across the Atlantic, enabling storms to intensify more easily.
Abundant atmospheric moisture will also aid in rapid strengthening of storms. When combined with the low wind shear and warm waters, all the ingredients are in place for explosive development of any tropical systems that form.
Examples of Rapid Intensification
We’ve already seen several striking examples of rapid intensification in the 2024 season:
- Hurricane Beryl strengthened from a tropical depression to a Category 4 hurricane in just 2 days
- Hurricane Francine quickly intensified to a Category 2 just before landfall in Louisiana
- Hurricane Otis (2023) went from a Category 1 to a catastrophic Category 5 in only 15 hours before hitting Mexico
These storms demonstrate how quickly conditions can change, leaving little time for preparation. Rapidly intensifying storms are especially dangerous when they form close to land, as Francine and Beryl did.
What to Expect for the Rest of the Hurricane Season
With ocean temperatures remaining extremely warm and La Niña expected to redevelop, conditions will remain very favorable for rapid intensification throughout the peak of the 2024 hurricane season. More major hurricanes forming close to the U.S. and Caribbean are a significant concern.
However, as we head into October, sea surface temperatures should begin to cool, reducing the threat somewhat. But remember, it’s the depth of the warm water that matters most for intensity.
Hurricanes can still form in late October and November, so it’s important to stay vigilant.
Be Prepared for an Active Season
With the peak of the 2024 Atlantic hurricane season still to come, it’s crucial to stay informed and have a plan in place.
Pay attention to the latest forecasts from the National Hurricane Center and your local officials. Have supplies ready in case you need to evacuate or shelter in place.
While we can’t stop hurricanes from rapidly intensifying, being prepared can make all the difference in staying safe this season. Don’t let your guard down – more dangerous storms are likely on the way.
Source:
1. National Weather Service
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Nancy Maffia
Nancy received a bachelor’s in biology from Elmira College and a master’s degree in horticulture and communications from the University of Kentucky. Worked in plant taxonomy at the University of Florida and the L. H. Bailey Hortorium at Cornell University, and wrote and edited gardening books at Rodale Press in Emmaus, PA. Her interests are plant identification, gardening, hiking, and reading.
