2025 Atlantic hurricane update

 

Keeping an eye on the tropics at the shore

The peak of the Atlantic hurricane season in September is quickly approaching. That's when atmospheric and environmental conditions are the most favorable for tropical storm and hurricane development. Earlier this week NOAA updated its seasonal hurricane forecast to reflect the tropical activity over the first two months of the season.

NOAA's updated forecast currently expects a seasonal total of 13-18 tropical storms, of which 5-9 could become hurricanes, with 2-5 major hurricanes. This includes the four tropical storms that have already developed. An "average" hurricane season features 14 tropical storms, 7 hurricanes and 4 major hurricanes. The two primary reasons NOAA scientists expect an average to slightly above average season are warmer ocean water over the tropical Atlantic and the lack of El Nino or La Nina conditions.

One of the trademarks of La Nina conditions in the tropical Atlantic is a reduction in the amount of wind shear. Wind shear refers to winds that change in both speed and direction at different levels of the atmosphere. Less wind shear means conditions are more favorable for tropical development. El Nino conditions often produce more wind shear in the tropical Atlantic that creates less favorable conditions for tropical development. The absence of both are expected to continue into the fall.

The four tropical storms that have already developed this season have been relatively weak and short-lived. Only Chantal made landfall in the United States as a 60 mph tropical storm in South Carolina on July 6. No hurricanes have developed anywhere in the Atlantic Ocean since last November.

The National Hurricane Center doesn't expect any other tropical storms to develop in the Atlantic over the next few days. However, they’re watching the tropical Atlantic for a disturbance that could become Tropical Storm Erin next week.

As recent seasons have shown, things in the tropical Atlantic can ramp up in a hurry. The 2017 Atlantic hurricane season, for example, got markedly more active in late-August, starting with Hurricane Harvey. September 2017 saw four major Atlantic hurricanes, including two Category 5 powerhouses (Irma and Maria). 

The 2020 Atlantic hurricane season had more named tropical storms than any season on record.  It was a back-loaded season with four major hurricanes after October 15. That’s not to say this season will feature similar trends as 2017 or 2020, but atmospheric and environmental conditions are the most conducive for tropical development in September.