Forecasters predict another active Atlantic hurricane season 2025 » Yale Climate Connection

The Colorado State University hurricane forecast team may once again be held in 2025, the Atlantic hurricane season of 2025. (26% above average). This is higher than the long-term average of 14.4 named storms, 7.2 hurricanes, 3.2 major hurricanes and 123 aces during the period 1991-2020. Last year, there were 18 named storms, 11 hurricanes, 5 hurricanes, 5 hurricanes, five major hurricanes, ace and 162 aces and 162 aces, and only two of the past decade have been in the 202 seasons below 2010, accounting for 201, below 202, below 202 seasons below.

CSU Outlook predicts that the chances of a major hurricane hit the United States are higher than usual: 51% (long-term average: 43%). This gives major hurricanes a 26% chance of hitting the East Coast or the Florida Peninsula (long-term: 21%) and a 33% chance of hitting the Gulf Coast (long-term average: 27%). A 56% chance of the Caribbean has at least one major hurricane pass (long-term average: 47%).

CSU predictions used a statistical model that honed from Atlantic hurricane statistics over the past 40 years, plus four groups of dynamic model outputs: ECMWF (European Model), UKMET, Japan Meteorological Service and Centro Euro-Mediterraneo Suii Cambiamenti Climatici (CMCC).

The CSU team cites two main reasons for its forecast for 2025 average:

1) ENSO-ENSO neutral or weak LaNiña conditions seem to be possible this fall

La Niña conditions have been weak in the Eastern Pacific region in recent months, with most models being predicted neutral or weak La Niña conditions for the peak of the Atlantic hurricane season. NOAA's Climate Forecasting Center predicted in its latest consultation on March 13 that there are 49% chances for neutral conditions, 38% chances for LaNiña, and 13% chances for ElNiño.

Due to the increase in high-rise winds on the tropical Atlantic, El Niño phenomenon favors slower than usual Atlantic hurricane season, which tear apart the storm (higher vertical wind shears). In contrast, positive hurricane season is more likely when neutral or La Niña conditions are present. Since 1950, the U.S. hurricane has been more than twice as likely to land in La Niña in the year compared to the current El Niño (Figure 2).

2) Ocean temperature mode

Currently, sea surface temperatures are much higher than average in the western and eastern subtropical Atlantic Oceans, and sea surface temperatures are almost below average in the eastern tropical Atlantic Oceans (Figure 1). Warm enhancements in the eastern subtropical Atlantic and Caribbean are associated with good results that are typically seen in April before the active Atlantic hurricane season.

As a practice, the CSU team includes this standard disclaimer:

“Remind coastal residents that only a hurricane is needed to make it their active season. Every season should be thoroughly prepared, no matter how many activities are predicted.”

Simulation Year

Five-year preseason for January, February and March atmospheric and ocean conditions were selected as the “simulated” years where the 2025 hurricane season may be similar. These simulated years occur the second year after the El Niño event and are under LaNiña conditions from January to February of that year. In the tropical and subtropical Atlantic Oceans, simulated years of sea surface temperatures are also above average. The simulated year is:

• 1996 (13 named Storms, 9 hurricanes and 6 major hurricanes)
• 1999 (12 named Storm, 8 hurricanes and 5 major hurricanes)
• 2006 (10 named storms, 5 hurricanes and 2 major hurricanes)
• 2008 (16 named storms, 8 hurricanes and 5 major hurricanes)
• 2011 (19 are called “Storm”, 7 hurricanes and 4 major hurricanes)
• 2017 (17 named Storms, 10 hurricanes and 6 major hurricanes)

The average activity for these years was 14.5, named Storm, 7.8 hurricanes, 4.7 major hurricanes and 154 aces – the activity level was above average. During the simulation period, 2017 was a notorious age, with three categories of Category 4 hurricanes causing the U.S. landings: Harvey, Irma and Maria. However, 2006 was quiet, with no hurricane landing anywhere in the Atlantic Ocean.

Warning: April hurricane season forecasts have little or no “skills”

When calculated using the root mean square skill score, on average, April’s forecast of hurricane season activity has no “skills” or even negative skills. This does not mean that a particular April forecast will be incorrect, but, on average, predictions that use climatology alone are the same or better. April’s forecasts must deal with the so-called spring predictability barrier. In April, the Elniño/LaNiña phenomenon usually changes rapidly from one state to another, so it is difficult to predict whether Elniño, LaNiña or neutral conditions will be achieved in the upcoming hurricane season.

In April 2024, CSU predicted a very active season – 23 called “Storm”, 11 hurricanes, 5 major hurricanes and 210 aces. The forecast performed well because the actual activity was 18 called Storms, 11 hurricanes, 5 major hurricanes, 5 major hurricanes, 162 aces and 162 aces. However, their forecasts for April 2023 and 2022 are not very good.

The next CSU forecast, June 11, deserves close attention as the late May/early June forecasts have shown considerable skills over the years. In other aspects of prospects:

• NOAA will release its first seasonal hurricane forecast for 2025 in late May.
• British private forecasting company Tropical Storm Inc. will release its forecast for the following 2025 Atlantic hurricane season on April 7. The first forecast for the season, released on December 10, requires 15 named Storms, seven hurricanes, three major hurricanes, three major hurricanes, the ACE index and 129 ACE index.

read: How to develop an evacuation plan

Bob Henson contributed to this article.