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Sixth straight above-average hurricane season on the cards

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Weather forecasts indicate another above-normal North Atlantic hurricane season this year after a bumper 2020, risk modelling firm RMS says.

That would mark a record sixth consecutive above-normal season, which runs from June to November.

The National Oceanic and Atmospheric Administration (NOAA) calculates a 60% probability the 2021 North Atlantic hurricane season will be above normal, with a likely 13–20 named tropical storms, 6–10 hurricanes and 3–5 major hurricanes.

Of the past 26 hurricane seasons, 17 (65%) have been designated above normal, five (19%) near normal and four (15%) below normal.

Most forecast models favour cool-neutral conditions throughout the remainder of 2021, RMS says, with an increasing possibility that La Niña conditions could re-emerge during the northern hemisphere’s late autumn or winter.

The official El Niño-Southern Oscillation (ENSO) forecast indicates a greater probability of La Niña conditions during September-November and onwards. Should ENSO remain in a neutral phase throughout the 2021 hurricane season, and in the absence of influence from any other factors, activity would be expected to be near normal.

“A large proportion of the uncertainty associated with seasonal hurricane activity forecasts can be attributed to the uncertainty of which phase of the El Niño-Southern Oscillation (ENSO) will materialise during the peak months of the hurricane season during August, September, and October,” RMS Chief Risk Modelling Officer and Executive VP Models and Data Mohsen Rahnama said.

Last season, the Atlantic Basin experienced a record-breaking hurricane season, exhausting the storm name list for only the second time in history, with 30 tropical storms, 14 hurricanes and 6 major hurricanes.

Insured losses were lower than in other active seasons though, estimated by RMS at between $US19-30 billion ($25-39 billion) for the six landfalling US hurricanes – the equivalent of just one of 2017’s three destructive hurricanes.

In the Western Pacific Basin, Japan registered no tropical cyclone landfalls for the first time in 12 years in 2020.