[vc_row][vc_column][vc_column_text]
Extended Range Forecast for North Atlantic Hurricane Activity in 2024
Author: Dr. Adam Lea & Nick Wood
Published: 11th December 2023
Forecast Summary
TSR predicts that North Atlantic hurricane activity in 2024 will be very active with activity about 30% above the 1991-2020 30-year norm and around 50% above the long-term 1950-2023 norm. This outlook has large uncertainties.
The TSR (Tropical Storm Risk) extended range forecast for North Atlantic hurricane activity in 2024 anticipates a season with high activity. The forecast spans the period from 1st June to 30th November 2024 and employs data through to the end of November 2023. TSR uses the forecast August-September sea surface temperatures in the Atlantic Main Development Region (10º-20ºN, 60º-20ºW) and the forecast July-September Caribbean trade wind anomaly over the region 7.5º-17.5ºN, 100º-30ºW as predictors. The former is forecast to be warmer than average leading to an enhancement of Atlantic hurricane activity, and the latter is predicted to be weaker than normal due to predicted neat neutral ENSO conditions and above average sea surface temperatures in the Caribbean Sea. This forecast has high uncertainty due to uncertainty in how warm the Atlantic and Caribbean Sea sea surface temperatures will
be in August-September 2024 and by how much this will influence the strength of the Caribbean tradewinds. We express the forecast uncertainty in terms of probability of exceedance for Accumulated Cyclone Energy (ACE) and for hurricane numbers.
North Atlantic ACE Index and System Numbers in 2024
The forecast tercile probabilities (1991-2020 data) for the 2024 North Atlantic hurricane season ACE index are as follows: a 53% probability of being upper tercile (>156)), a 39% likelihood of being middle tercile (75 to 156)) and only an 8% chance of being lower tercile (<75)).
Forecast Probability of Exceedance Plots for the 2024 North Atlantic Hurricane Season
Seasonal outlooks for North Atlantic hurricane activity contribute to the anticipation of risk for insurance companies, other weather-sensitive businesses, and local and national governments. However, the uncertainty associated with such forecasts is often unclear. This reduces their benefit and contributes to the perception of forecast ‘busts’. The robust assessment of risk requires a full and clear probabilistic quantification of forecast uncertainty with the forecast issued in terms of probability of exceedance (PoE). In this way the chance of each hurricane number/activity outcome occurring is clear for the benefit of users. Going forward TSR is including robust forecast probability of exceedance (PoE) information based on the recommendation and methodology described in Saunders et al. (2020).
The plots below display our extended range outlooks for ACE (upper panel) and for the number of hurricanes (lower panel) in terms of PoE. Each plot displays three sets of PoE data comprising the forecast PoE curve and two climatology PoE curves. The forecast PoE curves are computed using the method described in section 3 of Saunders et al. (2020) while the climatology PoE curves are computed directly from observations. The two forecast PoE plots specify the current chance that a given ACE index and/or hurricane total will be reached in 2024 and how these chances differ to climatology.
Reference: Saunders, M. A., Klotzbach, P. J., Lea, A. S. R., Schreck, C. J., & Bell, M. M. (2020).
Quantifying the probability and causes of the surprisingly active 2018 North Atlantic hurricane season.
Earth and Space Science, 7, e2019EA000852. https://doi.org/10.1029/2019EA000852
For further information: TSRATLForecastDecember2024.pdf (tropicalstormrisk.com)
[/vc_column_text][/vc_column][/vc_row]