2021 Atlantic Hurricane Forecast: Another Active Season?

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While the official early forecast won’t come from Colorado State University until April 8th, many factors are being considered already towards the upcoming season after a very active 2020 season.

The outlook, which is championed by Dr. Phil Klotzbach of Colorado State University, says that there is about a 6 in 10 shot of another active hurricane season ahead.

The two such drivers that Dr. Klotzbach says are key to figuring out how busy next season will be are both related to water – the status of El Niño Southern Oscillation (or ENSO) and how water temperatures in the northern Atlantic change in the next year.

Water temperatures have cooled in the Pacific since this past summer in a phenomenon called La Niña. This co-operative oceanic/atmospheric occurrence is one of the reasons that this past hurricane season was record-breakingly busy.

La Niña typically allows for more favorable atmospheric conditions in the Atlantic while its counterpart pattern, El Niño, typically allows fewer tropical storms and hurricanes to form.

Most modeling suggests that the Pacific will gradually warm through this preparation season and into the first half of hurricane season. By the time hurricane season heats up, in July, August, and September water temperatures should be warm enough to be considered at least neutral.

For the last quarter-century, water temperatures have been running naturally above average at the height of a cycle called the Atlantic Multidecadal Oscillation (or AMO).

The typical period of the AMO is about 60 years, with the period length varying between as short as 40-50 years and as long as 70-80 years. This means that we typically have 25-35 years of above-average Atlantic basin major TC activity and similar length periods with considerably reduced amounts of major TC activity, according to CSU.

The best hope would be cold water moving off the coast of Greenland and Iceland, which basically “turns off” the flow between Africa and the Atlantic during hurricane season. But, considering the last 5 seasons, this seems unlikely.

So, in short, we will have to wait until April 8th before the forecast is more clear, but rooting for El Nino would be the best bet for a quiet season and a break from the last 5 years.

 

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