Here we go again, y'all. The Atlantic hurricane season started Sunday and will last through the end of November. Once again, we're likely to see a busier-than-average season in the Atlantic Basin. However, things are different than they were over the last few hurricane seasons, so we don't anticipate a hyperactive season this year. Here are the outlooks from the two best-known entities for hurricane season activity outlooks, alongside what happened in the last two years and the average.
Many other private sector, university, and government entities also issue seasonal outlooks for the Atlantic, and you can see a complete list of them at the URL in the above graphic.
A significant amount of information and research goes into issuing one of these outlooks. The two primary factors influencing an Atlantic Basin outlook are the state of ENSO (El Niño-Southern Oscillation, which involves the combination of water temperatures over the equatorial central and eastern Pacific Ocean relative to normal and their impact on global circulation) and sea temperatures across the tropical and subtropical parts of the Atlantic Basin.
Both of these factors are different than the last couple of years. In 2023, an El Niño (characterized by warm equatorial waters in the central and eastern Pacific) was ongoing, while in 2024, a La Niña (characterized by cool equatorial waters in the east and central Pacific) was present. Currently, we have neither one in progress; water temperatures in the ENSO region of the Pacific are near average. We refer to this as ENSO neutral conditions; the more jovial scientist may call it "La Nada." The state of ENSO is essential because it has a big impact on Atlantic hurricane activity. During El Niño, we tend to see westerly winds aloft over the Caribbean Sea and tropical Atlantic Ocean, leading to vertical wind shear that tears tropical cyclones apart. The air over these regions also tends to be less humid and more stable, which makes it harder for thunderstorms and tropical cyclones to develop. The opposite is true during La Niña; you tend to see lighter winds aloft, and the air over the tropical Atlantic Basin is more humid and more unstable. So, you tend to see more storms form in the Atlantic during La Niña. The ENSO-neutral conditions we currently have tend to result in a somewhat more active hurricane season, but not to the extreme that we see with La Niña. You can find a more detailed explanation and graphics to go along with it from the Climate Prediction Center.
Sea temperatures across the Atlantic Basin are critical because warm ocean waters are fuel for a tropical cyclone. The warmer the ocean waters are, the more intense a tropical cyclone can become. In recent years, the waters across the tropical and subtropical Atlantic have been far warmer than normal. At times, the area-average temperature has been at record warmth. However, this has changed in recent months. The tropical Atlantic has cooled considerably, and the Caribbean Sea isn't as warm as it has been. However, most of this area remains warmer than average. This serves to enhance the potential for Atlantic hurricane activity this year, but it's not as favorable as it has been in the last few years.
A plot of sea surface temperature anomaly across the North Atlantic Ocean for June 1.
Image Source: WeatherBELL
Seasonal forecasters consider several other factors in their outlooks, such as statistical correlations between hurricane activity and eastern Atlantic water temperatures from January through March and upper-tropospheric winds over a particular part of the Atlantic during that period. They also consider the output of long-range computer models. Another critical factor is what we call analog years, times in the past when similar conditions were observed in the period leading up to the start of the hurricane season to what we are seeing this year. Most of these factors point toward an active, but not hyperactive, Atlantic hurricane season this year.
As is typical for the first few days of the hurricane season, not a lot is happening over the Atlantic Basin. A tropical wave is over the eastern Atlantic near Cabo Verde. That area is unfavorable for development during June, so we don't expect further development. In a week, it will reach the Caribbean Sea, where things will be less hostile for it; we'll pay closer attention to it then. Another interesting feature over the Atlantic is a front that has become stationary over the Gulf of Mexico and southwestern Atlantic. However, there is no sign of further development at the moment, and it would take days for anything to get underway here.
It's worth mentioning that some long-range computer model output shows a storm forming either near the Yucatan Peninsula or off the Southeast Coast in about a week. This is mainly coming from our GFS model, which tends to catch developing storms earlier than others but it also generates a ton of false alarms. Other models, such as everyone's favorite, "The Euro," have been less bullish about this scenario. It's something to keep an eye on for next week, but don't panic.
This loop of visible satellite imagery shows clouds with a tropical wave over the eastern Atlantic near Cabo Verde, and an area of clouds over the Gulf of Mexico and southwestern Atlantic associated with a stationary front.
Image Source: University of Wisconsin RealEarth
Hurricane season is here, and I hope you're ready. After all, we just had a whole Hurricane Preparedness Month in May. If you're not (I know, procrastinators are gonna procrastinate), it's time to get up to speed. Once again, SCEMD has plenty of hurricane prep resources to help you over at hurricane.sc, so head over that way to find out what you need to be ready for the hurricane season, and the things you need to know should a hurricane head our way this year.