Conditions remain conducive for an above-average Atlantic hurricane season, the National Oceanographic and Atmospheric Administration (NOAA) reported in early August.
According to the latest NOAA outlook, the number of expected named storms (winds of 39 mph or greater) is 15 to 21, including seven to 10 hurricanes (winds of 74 mph or greater), of which three to five could become major (Category 3, 4 or 5 with winds 111 mph or greater). This updated outlook includes the first five named storms of the season. Hurricane Elsa became the earliest 5th named storm on record.
“After a record-setting start, the 2021 Atlantic hurricane season does not show any signs of relenting as it enters the peak months ahead,” said Rick Spinrad, NOAA administrator.
NOAA scientists predict that the likelihood of an above-normal 2021 Atlantic storm season is 65%. There is a 25% chance of a near-normal season and a 10% chance of a below-normal season.
“A mix of competing oceanic and atmospheric conditions generally favor above-average activity for the remainder of the Atlantic hurricane season, including the potential return of La Niña in the months ahead,” said Matthew Rosencrans, lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center.
Atlantic sea surface temperatures are not expected to be as warm as they were during the record-breaking 2020 season. However, reduced vertical wind shear and an enhanced west Africa monsoon all contribute to the current conditions that can increase seasonal hurricane activity. These conditions are set against the backdrop of the ongoing warm phase of the Atlantic Multi-Decadal Oscillation, which has been favoring more active hurricane seasons since 1995.
See an article about NOAA’s original projection for the season.
The NOAA update differs slightly from a report issued in early August by Colorado State University (CSU) researchers. The CSU team slightly reduced the number of storms and hurricanes it expects in the 2021 Atlantic hurricane season. Those researchers reduced the number of expected storms to 18, down from 20 in July, and reduced the expected number of hurricanes to 8, down from 9 in July. The CSU storm and hurricane projections lie within the range expected by NOAA.
Source: National Oceanic and Atmospheric Administration
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