May Updated Forecast for the 2021 Atlantic Hurricane Season

12 05 2021

Dale C. S. Destin |

The numbers for this Atlantic hurricane season could challenge those of the record breaking 2020 Season. My updated forecast for the 2021 Season is out, and it continues to call for an above normal season being likely. It is also possible that the season could be super hyperactive.

The prediction is for 22 named storms (tropical storms and hurricanes), with a 70 confidence or high confidence of the number ranging between 15 to 29. It is also likely–58 percent chance, that the number of named storms will exceed 19 and be in the top 10 percentile of the historical record, dating back to 1851.

My forecast also calls for an accumulated cyclone energy (ACE) index of 179 (down 5) with a high confidence of the range being 89 to 266. There is also a 35 percent chance chance of the ACE index exceeding 223, super hyperactive or in the top 10 percentile of the 1991-2020 climatology. Also predicted are 10 hurricanes (up 1) with a 70 percent confidence of  the total being 6 to 14, and 4 major hurricanes (down 1) with high confidence of 2 to 7.

If this forecast pans out, this season would be the third most active since 2005, in terms of ACE, and the 14th most active on record dating back to 1851. It would also be ranked third for the highest number of named storms and tied for 9th and 19th for the most hurricanes and major hurricanes respectively. Further, the season would be deemed extremely active (hyperactive) according to the National Oceanic Atmospheric Administration (NOAA) criteria i.e. ACE greater than 159.6.

According to other forecasts surveyed, the consensus is for an ACE of 152, 18 named storms, 8 hurricanes and 4 major hurricanes – an above normal season. This is generally consistent with my forecast but with a notable 18 percent less activity (ACE); notwithstanding, I am very confident in the 268Weather forecast. Nevertheless, regardless of the forecast, you should always prepare the same each season, as it only takes one hurricane to ruin your year and or life.

The 2020 hurricane season had a record 30 named storms, 14 hurricanes and a record tying 7 major hurricanes. There was also an ACE index of 185. Overall, the 2020 season is ranked 10th, based on ACE. The most active season, since record began in 1851, remains 1933, with an ACE of 259. Note, based on post-analysis, Tropical Storm Gamma was upgraded to a Category 1 hurricane on 17 April 2021 and Category 2 Hurricane Zeta was upgraded to Category 3 on 10 May 2021.

The main reasons for the above normal forecasts are the likely above normal sea surface temperatures across the tropical North Atlantic and a weak La Niño and or cold-neutral El Niño Southern Oscillation (ENSO) during August to October–the peak of the hurricane season.

A typical season, based on the standard climate period 1991-2020, has 14 named storms, 7 hurricanes and 3 major hurricanes. Major hurricanes have sustained wind speeds of at least 178 km/h or 111 miles per hour (e.g., Category 3 or higher), according to the Saffir Simpson Hurricane Wind Scale.

This forecast will be updated monthly around the 10th each month until August. The next update will be issued around June 10.

The Atlantic hurricane season officially begins on June 1 and concludes on November 30; nevertheless, in the last five years, there have been preseason tropical cyclones–be prepared early!

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