The chief risk modelling officer at Moody’s RMS says this year’s North Atlantic hurricane season is set to be near normal but the rapid heating of the ocean’s waters presents a challenge.
Mohsen Rahnama (pic) was speaking as the organisation issued its forecast for 2023 which indicates that a near-normal season is most likely, due to the competing and opposing influence of several key factors such as the El Niño-Southern Oscillation (ENSO) and above-average North Atlantic sea surface temperatures.
However, RMS warned it only takes one event to make a season costly or memorable, as seen during last year’s near-normal season with Hurricane Ian, anticipated to be one of the costliest US. hurricanes on record and to reshape insurance markets for years to come.
It comes after the US National Oceanic and Atmospheric Administration (NOAA) outlook for the 2023 North Atlantic hurricane season predicts that a near-normal season is most likely, with lower but equal possibilities that the season could be above or below normal. The NOAA outlook indicates a 40 percent probability that the season will be near normal, a 30 percent probability that the season will be above normal, and a 30 percent probability that the season will be below normal.
NOAA’s forecast contains a 70 percent probability that the 2023 season will produce:
- 12–17 named storms
- 5–9 hurricanes
- 1–4 major hurricanes
- Accumulated Cyclone Energy (ACE) index of 91–188
The predicted ranges for activity in 2023 are centred near NOAA’s 1991–2020 US Climate Normals seasonal average of 14 named storms, seven hurricanes, and three major hurricanes.
If NOAA’s forecast verifies, the 2023 North Atlantic hurricane season would be a second consecutive near-normal season.
RMS said the development of El Niño would typically result in a quieter hurricane season, but the higher sea surface temperatures would fuel more activity. The season could conclude with below- or above-normal activity if one of these competing factors exhibits a greater influence.
Beyond the US and the Americas, the outlook includes forecasts that predict typhoon activity in the Western North Pacific Basin in Asia-Pacific will be above average, given El Niño’s particular impact on the region, resulting in an increase in atmospheric instability.
The outlook also evaluates the historical performance of North Atlantic seasonal activity forecasts.
Rahnama added that last year may have been seen as around average but the insurance industry will remember the season for only one event: Hurricane Ian.
“Ian was a historic and complex event that caused catastrophic wind and storm surge damage in southwestern and central Florida and the Carolinas,” he added. “Landfalling in a precarious Florida market amid rising inflation, Hurricane Ian is anticipated to be one of the costliest US hurricanes on record, and one that will reshape the Florida insurance market for years to come.”
He added the latest forecasts for 2023 indicate that a near-normal season is most likely.
“The forecasts reflect the competing and opposing influence of several key seasonal oceanic and meteorological factors that typically influence intraseasonal hurricane activity in the North Atlantic,” Rahnama explained. “This includes the El Niño-Southern Oscillation (ENSO) and North Atlantic sea surface temperatures. The development of El Niño would typically result in a quieter hurricane season than normal, but sea surface temperatures in the North Atlantic, and in particular in the main development region, are anticipated to be well above average throughout the year.
“These factors – some that suppress storm development and some that fuel it – have resulted in the overall forecast for a near-normal season. However, there remains a reasonable possibility that the season could conclude with below- or above-normal activity if one of these competing factors exhibits a greater influence over the season.”
“While the U.S. has primarily been the focus of tropical cyclone-insured losses in the past three years, Moody’s RMS stands ready to respond in the Western North Pacific Basin if the focus switches,” he continued.