July Updated Forecast for the 2021 Atlantic Hurricane Season

12 07 2021

Dale C. S. Destin |

Category 1 Hurricane Elsa going through the southern Caribbean July 2, 2021.

Not the potentially stressful news anyone wants to hear, but it is what it is; the 2021 hurricane season could challenge the numbers of the 2020 record breaking season. My updated forecast for the Season is out, and it continues to call for an above normal season being pretty much expected. The confidence of an above normal season has increased to 79%. It is also possible that the season could be super hyperactive or well above normal, with numbers reaching the top 10 percentile 1991-2020 base period, which would also be top 8 of all times, dating back to 1851.

The prediction is now for 24 named storms (subtropical storms, tropical storms and hurricanes), with a 70 percent confidence or high confidence of the number ranging between 18 to 31. It is also very likely–74 percent chance (up 18), that the number of named storms will exceed 19 and be in the top 4 seasons of the historical record, dating back to 1851.

My forecast also calls for an accumulated cyclone energy (ACE) index of 191 (up 5) with a high confidence of the range being 119 to 288. Also predicted are 10 hurricanes (up 1) with a 70 percent confidence of  the total being 7 to 14, and 5 major hurricanes (unchanged) with high confidence of 3 to 7.

The season could not only be above normal but well above normal or super hyperactive. There is also a 45% chance of the ACE exceeding 223, the top 10 percentile of the 1991-2020 base period. Further, there is a massive 74% chance of more than 19 named storms or the number of named storms reaching the top 10 percentile. There is also a 45% chance of more than 11 hurricanes and 44% chance of more than 6 major hurricanes.

If this forecast pans out, this season would be the most active since 2017, in terms of ACE, and the 10th 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 for the most hurricanes and major hurricanes respectively.

If the season turns out to be hyperactive, as is possible, it will rank even higher. Only seven seasons have had a higher ACE than 223; three seasons with more than 19 named storms; four with more than 11 hurricanes and two with more than 6 major hurricanes.

Already, the season is off to a “flyer”. Already, there has been five named storms (close to four times the average to date) and one hurricane (close to three times the average to date) . The ACE to date is 12.8. In other words, year-to-date, there is normally 1-2 names storms, instead of 5; 1 hurricane every three years and ACE of 4, as opposed to 12.8, which is over three times the normal rate, up to this point in the season.

The main reasons for the above normal forecasts are the likely above normal sea surface temperatures across the tropical North Atlantic Ocean and a weak La Niña conditions and or a 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 is updated monthly around the 15th each month until August. The next update will be issued around August 15. Note that these forecasts are to be taken as guides and not as gospel.

The Atlantic hurricane season officially began on June 1 and will conclude on November 30. Be prepared! Please share this blog, if you found it useful and follow me for more on the ongoing hurricane season, which, god forbid, could be another wild one like last year; also follow for all things weather and climate – TwitterFacebook and Instagram.

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