Storms

2020 Atlantic hurricane season likely to be more severe than usual

                        

According to current forecasts, the upcoming hurricane season will be more severe than the long-term average. Against the background of the coronavirus pandemic, severe hurricanes making landfall would pose additional challenges to response and recovery, including labour shortages, supply chain issues, and longer, more challenging coastal evacuations. This makes it all the more important this year to focus on prevention and loss reduction measures.

02.06.2020
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Most seasonal forecasts currently expect 16 or more tropical cyclones to form in the North Atlantic, which is in line with Munich Re’s expectations for the season. Of these, 8 could reach hurricane strength, and 4 could even develop into major hurricanes (Saffir-Simpson Wind Damage Potential Scale categories 3–5 with wind speeds of more than 95 knots/178 km/h). However, there are uncertainties in these forecasts.

In comparison: the long-term average (1950–2019) for the number of tropical cyclones per season in the North Atlantic is around 12. Of these, an average of 6.3 reach hurricane strength and 2.5 become major hurricanes. The anticipated storm activity for 2020 corresponds roughly to the average values for the Atlantic Multidecadal Oscillation (AMO) warm phase since the mid-1990s in the tropical North Atlantic that has favoured the development of storms.

Actual storm counts remain difficult to predict as they are influenced by a large number of atmospheric and oceanic factors. The state of the El Niño-Southern Oscillation (ENSO) in the Pacific, for example, is of crucial importance in this context. Hurricane activity in the North Atlantic tends to be reduced during El Niño phases, whereas an above-average number of severe typhoons can develop in the Northwest Pacific under the same conditions.

For the season just beginning, forecasts from the month of May expect weak El Niño  conditions currently seen in the eastern equatorial Atlantic to disappear, with neutral conditions close to borderline La Niña or even beyond forecast for the main months of the hurricane season (August–October). For this reason, it is unlikely that climate variations will have any mitigating influence on storm activity in the Atlantic this year. At the same time, water temperatures in the tropical North Atlantic are expected to be higher than average, meaning there is more fuel available for potential intensification of storms.

Losses from tropical cyclones © Munich Re

For the typhoon season in the Northwest Pacific, neutral ENSO conditions would mean that cyclone activity should be close to the long-term average (26 named typhoons, of which 9 reached the severest categories). In the years of 2018 and 2019, a specific ENSO type called the Central Pacific El Niño (El Niño Modoki) was present in the Pacific. During an El Niño Modoki, typhoon tracks are more frequently steered in the direction of Japan, which resulted in very high losses caused by typhoon in the last two years. For the typhoon season 2020, the currently available forecasts fortunately do not expect such a pattern to repeat itself.

But one thing is clear: as a result of the coronavirus pandemic, countries and societies are now more susceptible in the event of a natural disaster because disaster recovery resources may be under considerable strain for the indefinite future. Countries like the Bahamas – which was devastated last autumn by Hurricane Dorian with extreme wind speeds in excess of 300 km/h – would be particularly vulnerable, especially since the country is not only still dealing with the damage from that event, but also with the financial impact from the absence of tourists.

As usual, it is not possible to forecast losses for the tropical cyclone season that is now starting in the northern hemisphere. Potential tracks and landfalls can only be estimated for specific storms, and then only days in advance. Given the extreme losses from tropical cyclones, a key factor in long-term loss prevention will be to ensure storm-resistant building construction. All it takes is a single extremely powerful storm to hit a major urban area for devastating losses to occur. Munich Re’s NatCatSERVICE database shows that more than 80% of the US$ 1.5tn in losses from tropical cyclones since 1980 were caused by particularly severe storms. 

Munich Re experts
Eberhard Faust
Eberhard Faust
Head of Research: Climate Risks and Natural Hazards
Mark Bove
Mark Bove
Senior Research Scientist
Munich Re US
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