May 23, 2018

The 2017 Atlantic hurricane season saw an above average number of systems and is regarded as the costliest hurricane season on record. Of the 17 named systems that developed during the 2017 season, 10 reached hurricane-strength. Six of the storms reached major (Category 3 or above) hurricane strength. Billions of dollars of damages were inflicted in the US and Caribbean, with much of the destruction attributed to hurricanes Harvey, Irma, and Maria. 

Some areas, including Puerto Rico and Dominica, are still recovering from the passage of major storms. As the start of the 2018 Atlantic hurricane season draws near, businesses, employees, travelers, and residents in areas vulnerable to tropical activity should maintain situational awareness of the latest tropical forecasts and review contingency plans should a tropical system approach.

Pre-seasonal Hurricane Forecast for 2018

The Atlantic hurricane season runs annually from June 1 through Nov. 30. Pre-seasonal forecasts issued by private, governmental, and academic institutions generally favor a slightly above-average number of tropical systems in 2018. These predictions, although not the most accurate, give an early look at what might occur in the Atlantic Basin by taking into consideration a number of environmental factors. A typical season consists of an average of 12 named storms each year, half of which become hurricanes; of these storms, an average of three attain major hurricane status (Category 3 or greater on the Saffir-Simpson intensity scale). The majority of pre-season forecasts suggest there could be a higher-than-average number of both named storms and hurricanes this year, and that we’ll see a typical season when it comes to the number of major hurricanes. 

Environmental Factors That Impact Tropical Storm Formation

The pre-seasonal forecasts for tropical activity in the Atlantic Basin are largely based on several atmospheric and oceanic factors that help or inhibit tropical formation. One major influence is the temperature of ocean water. Currently, cooler-than-normal sea surface temperatures are present in the eastern and north central Atlantic Ocean. If this trend persists into the summer months, less tropical development is possible off the coast of Western Africa, at least during the beginning of the hurricane season.

Another factor that typically plays a significant role in the activity levels of a given season is the phase of the El Niño-Southern Oscillation (ENSO). Currently, the La Niña phase of ENSO is fading in the equatorial Pacific Ocean; this phenomenon played a key role in the hyperactivity seen during the 2017 Atlantic hurricane season. Climate models indicate that neutral conditions will likely materialize by summer, which typically correlates with near-normal storm formation. If there is a quick transition to El Niño conditions - a phase of ENSO that typically inhibits tropical formation - there could be fewer storms as a result. An unusually strong El Niño played a key role in the below-average hurricane season in 2015. El Niño weather patterns typically produce large amounts of vertical wind shear, which is defined as the change in wind speed or direction with altitude; shear is known to disrupt thunderstorm development and tropical strengthening. Continual monitoring of the ENSO phase will contribute to more reliable forecasts for tropical activity as the season gets underway.

Hurricane Preparation: Vital Steps for Mitigating Loss

Pre-seasonal forecasts of tropical activity are important tools used by emergency managers and insurance agencies to allocate appropriate resources, but the predictions often fail to provide insights into the number of systems that could potentially make landfall. Even a below-average season can still result in major supply chain disruptions and economic impacts if just one strong system comes onshore. Flooding, storm surge, and destructive winds not only threaten the personal safety of those operating in the path of the storm, but also have the potential to destroy infrastructure, complicate supply chain operations, and contribute to major transport disruptions. Keeping the learned lessons from the 2017 Atlantic hurricane season in mind, it is vital for individuals operating in vulnerable areas to prepare well in advance.

Having robust hurricane preparedness plans, identifying and addressing possible liabilities, and obtaining adequate insurance policies are important steps to take prior to a quickly approaching storm. It is vital for those living, working, or traveling in the path of an incoming tropical depression, tropical storm, or hurricane to heed all mandatory evacuation orders and warnings from local, state, and federal authorities to preserve both life and property. Recognizing reliable and thorough sources of weather and emergency information during and after a storm can also ensure a quick and effective response and recovery after a storm.

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Download our 2018 Global Forecast Executive Summary to get insights into the La Niña weather pattern and how it's likely to influence global weather as well as other environmental and geopolitical risks impacting the world today.