NOAA calls for more storms in 2021

Hurricane Eta struck Central America as a Category 4 storm in November 2020. - Image: NHC

For the latest information on storm activity in the Cayman Islands, as well as information on how to prepare for hurricane season, visit Storm Centre.

The National Hurricane Center is calling for a more active season than previously forecast.

In its revised mid-season forecast, which was released on 4 Aug., the NHC increased the range of predicted named storms from 13-20 to 15-21. The new forecast calls for between seven and 10 hurricanes, with the lower end increasing by one. The total number of major hurricanes remains at three to five.

Diagram courtesy NHC.

In an article released on the website of the National Oceanic and Atmospheric Administration, lead seasonal hurricane forecaster Matthew Rosencrans said, “Predicted warmer-than-average sea surface temperatures in the tropical Atlantic Ocean and Caribbean Sea, weaker tropical Atlantic trade winds, and an enhanced West African monsoon will likely be factors in this year’s overall activity.”

The NHC is a division of NOAA which is based in Miami, Florida. Each year NOAA puts out a main forecast in May which is revised three times, as the season progresses. Those forecasts, together with a similar set of predictions from Colorado State University, are reviewed by the Cayman Islands National Weather Services, which then releases its own forecast.

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The NWS issued its predictions in April, which called for 17 named storms, eight hurricanes and four major hurricanes.

“Based on the revised predictions, there are no major changes to the forecast,” said NWS Director General John Tibbetts. “Our predictions, which were issued in April, will remain the same.”

Diagram: NHC

The revised forecast now calls for a 65% chance of an above-average hurricane season, 5% more than the previous forecast. The corresponding chances of a near-normal season dropped by the same 5%, while the chances of a below-average season remain at 10%.

Five named storms have developed in the Atlantic hurricane basin since the start of this year’s season, notably including Hurricane Elsa. NOAA said those storms were taken into consideration when arriving at the new forecast.

In July, Colorado State University released its revised forecast which also reflected an uplift in the number of predicted storms. Although forecasters are calling for an increased number of storms, the 2021 season is not expected to be as active as last year’s.

How storms are rated

A storm is named once it reaches maximum sustained winds of 39 miles per hour. It becomes a hurricane once it develops wind speeds of 74 mph or stronger. It is considered a major hurricane once its maximum sustained winds become stronger than 111 mph. Hurricanes are measured from Category 1–5; a major hurricane is any storm that reaches Category 3 or stronger.

Each year the Atlantic hurricane season runs from 1 June to 30 Nov.

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