The latest forecast update for the 2021 Atlantic hurricane season from Tropical Storm Risk (TSR) raises the teams prediction for number of named storms and hurricanes slightly, suggesting activity levels that could be up to 30% above the long-term average.
The hurricane season forecast from Tropical Storm Risk (TSR) is the latest in a series we’ve covered and all the forecast teams we track have pointed to another above average year for the Atlantic tropics.
The TSR forecast team had previously issued a long-range outlook for the 2021 hurricane season that called for 16 named tropical storms, 7 hurricanes and 3 major hurricanes for this coming season, which was above the long-term average, but closer to the near-term norm of the last ten years.
Now, the new forecast issued late yesterday calls for 17 named tropical storms, 8 hurricanes and 3 major hurricanes of Category 3 strength or greater, along with accumulated cyclone energy (ACE) of 134.
That puts the forecast now above the near-term average of the last ten years and aligns it closely with other recent predictions from forecasting teams.
“Although large uncertainties remain at this April forecast range we consider that the more likely scenario is for the North Atlantic Oscillation in April-May-June 2021 to be negative leading to warming of the tropical North Atlantic waters and for the El Niño Southern Oscillation in July-August-September to be slightly negative thereby contributing to reduced trade winds over the tropical North Atlantic and Caribbean Sea,” the TSR forecast team explained.
Both of those environmental factors are expected to enhance North Atlantic hurricane activity in 2021, the TSR forecast team explain and when plotting their forecast in terms of probability of exceedance (PoE), they see a 38% likelihood that we could see a ‘hyperactive’ season in 2021, which they define as an ACE greater than 165% of the median ACE for 1981-2010 (which would equal an ACE value of 152.5)
Insurance and reinsurance interests will find the probability of exceedance plots useful, hence we have reproduced them below. The full forecast report from TSR can be found here for reference.
TSR also provides a US landfalls forecast, detailing forecast storm and hurricane landfalls for the United States for the 2021 season.
They are calling for 4 named tropical storm landfalls and 2 hurricane landfalls in the 2021 Atlantic season, so well below the hyperactive year of 2020, but insurance and reinsurance interests will be more focused on the strength and geographic location of any potential landfalls that occur.
This landfalling storms forecast is aligned with the average of the last decade.
The TSR forecast team highlight factors that should be considered as there are, “large uncertainties in ENSO and in the North Atlantic and Caribbean Sea SSTs at this 4-month lead before the start of the hurricane peak season in August 2021.”
They also note that the skill level in hurricane season forecasts tends to climb after April, as greater certainty emerges in the expected climatology for the season ahead, with “moderate-to-good skill levels being achieved, on average, by early August.”
Which is why early forecasts for hurricane season aren’t generally a valuable input to portfolio preparations, for the insurance, reinsurance and insurance-linked securities (ILS) industry.
But they do provide some insight into what may be ahead and give a benchmark that can be compared against as new forecasts and updates come out in advance and during the hurricane season.
Adding the TSR forecast for the 2021 hurricane season to the data already aggregated from others of the main forecast teams tracked by the reinsurance and ILS industry, our Artemis average continues to sit at 18 named storms, 9 hurricanes and 4 major hurricanes, with ACE slightly higher at 150.
Track the 2021 Atlantic tropical storm and hurricane season on our dedicated page and we’ll update you as new forecasts and information emerges.