Hurricane Irma 2017

The 2024 Hurricane Season is predicted to be well above normal due to two primary factors: El Nino and warm ocean water.

Currently, a weakening El Niño is expected to transition to a La Niña state by late summer or early autumn. This transition should produce low wind shear conditions, favoring tropical cyclone development over the North Atlantic. Additionally, the Atlantic Main Development Region (MDR) remains at record warm levels, increasing the probability of major hurricanes. 

2023 Hurricane Season

Despite a strong El Niño, the Atlantic experienced its fourth most active season in 2023. There were 20 named storms, including 7 hurricanes, with 3 reaching major hurricane strength. The strong El Niño also significantly impacted the Azores-Bermuda Ridge, leading to its weakening. Consequently, most of the tropical cyclones that developed last year tracked northward and remained well out over the Atlantic. The weakened ridge also resulted in weaker trade winds and less Saharan dust, both contributing factors to warming sea surface temperatures.

2023 North Atlantic Tropical Cyclone Tracls

Primary Storm Factors for 2024

Wind Shear: During La Niña events, wind shear in the tropical Atlantic typically decreases. Wind shear refers to the change in wind speed and direction with altitude. Reduced wind shear creates favorable conditions for the development and intensification of tropical cyclones. With weaker wind shear, disturbances in the tropics can organize more effectively, potentially leading to more and stronger storms.

Vertical Wind Shear affects Hurricanes

Sea Surface Temperature: Another key reason for concern this year is the persistent above normal sea surface temperatures (SST) in the tropical North Atlantic. The North Atlantic main development region (MDR) is where many of the stronger hurricanes form and currently SSTs remain well above normal with the ocean heat content at levels in April, more typical for early July.

Atlantic Main Develpment Region

Saharan Dust: Hot, dusty air blown westward off the coast of Africa over the main development region from late spring to early fall tends to suppress the formation of tropical cyclones by restricting needed moisture and vertical air motion, as well as reducing the amount of sunlight reaching the sea surface and lowering ocean temperatures.  During 2023 the weakened Azores-Bermuda ridge significantly reduced dust levels, helping to promote tropical cyclone development.

NOAA image Saharan Dust over the eastern North Atlantic

Azores-Bermuda Ridge (Trade Winds and Storm Paths)
During La Niña years the Azores-Bermuda Ridge (a high-pressure system located in the North Atlantic), tends to be stronger than normal. This ridge is a key factor as to how far west tropical cyclones will move before turning northward. As the Azores-Bermuda Ridge strengthens during this hurricane season, I would expect an increased risk of tropical cyclone landfalls farther to the west than in 2023. Highest risk areas include the Caribbean, the US East Coast, and the Gulf Coast. On the plus side, a stronger Azores-Bermuda ridge increases trade winds which tend to cool sea surface temperatures. As the season progresses, it will be essential to stay informed about the evolving conditions and their potential impact on hurricane activity.

Azores-Bermuda ridge has a strong effect of tropical cyclone tracks

Hurricane Season Analogs for 2024
The North American Multi-Model Ensemble (NMME) is an experimental multi-model seasonal forecasting system consisting of coupled models from various modeling centers in the US and Canada. The NMME SST forecast analogs since 1966 for sea surface temperature anomaly currently show the closest matches to this year as 1970, 1975, 1999, 2010 and 2011. Based on these analog years, the highest frequency tropical cyclone tracks are shown below.

NMME SST forecast analogs storm tracks

2024 Hurricane Forecast Numbers
Most prognosticators of Atlantic Hurricanes are looking for a much above-normal season, some are predicting possibly record activity. In an average season, we normally see 14-15 named tropical cyclones, of which 7-8 become hurricanes and 3-4 become major hurricanes. This season is forecasted range is for 20-30 named storms, 8-16 hurricanes and 4-8 major hurricanes.

Specific Forecast Center Predictions

                                              Named Storms           Hurricanes            Major Hurricanes

Colorado State University                  23                                11                                5            AccuWeather                                      20-25                           8-10                           4-7 WeatherBell                                        25-30                          14-16                          6-8
University of Arizona                           21                                11                                5

NOAA (to be issued May 1st)

Mean                                                   24                                12                             6

Fred Pickhardt