Active hurricane seasons prompt early launch of tropical advisory site

A map showing the 31 subtropical and tropical depressions that formed during the 2020 Atlantic Hurricane Season.

Forecasters at the National Hurricane Center in Miami, Florida, have released their Atlantic outlook two weeks early, on 15 May, prompted by the rapid development of storms over the past six years.

This marks the first time that the NHC has moved up the launch of its tropical storm projection.

Over those six years, the first storms and, in some cases, the first hurricanes for the Atlantic basin have developed ahead of the official 1 June start date of the hurricane season.

“There were talks about changing the official start date of the Atlantic hurricane season, during our last regional hurricane conference, which was held online because of the COVID situation,” Cayman Islands National Weather Service chief meteorologist Kerry Powery told the Cayman Compass. “Those discussions were shut down, but as a fall back they moved the start date of the tropical outlook to May 15.”

The blank map of the Atlantic basins shows no storm activity. Map courtesy of NOAA.

The tropical outlook is currently live. It displays a map that tracks weather systems in the Atlantic, Caribbean and Eastern Pacific regions. As of Tuesday, 18 May, the site read, “Tropical cyclone activity is not expected during the next 48 hours,” while displaying a blank map of the Atlantic basin.

Although the NHC has moved up its tropical outlook, Powery said the NWS would not be issuing any additional preseason storm-tracking tools or devices unless it becomes necessary.

“We already have internal practices that take into account any tropical wave, weather inside or outside the Caribbean basin,” said Powery. “We monitor those tropical waves on a daily basis and issue warnings and advisories as necessary. So, we will not be issuing anything outside of what is standard practice.”

Climatological shift results in higher storm averages

Each year the six-month Atlantic hurricane season runs from 1 June to 30 Nov. Previously, the climatological range which was used to calculate the storm average spanned from 1980 to 2010. During that time, the season average was 12 named storms and six hurricanes, three of which were expected to become major hurricanes.

“The climatological average was changed in January, so it now runs from 1991 to 2020,” said Powery. “The change in the range has also resulted in an increase in the season average, which is now 14 named storms, seven hurricanes and three major hurricanes.”

Despite increase in the hurricane season average, forecasters are still calling for an above- average hurricane season. In their April pre-season predictions, forecasters called for 17 named storms, including eight hurricanes.

The NHC is expected to release an updated forecast on 20 May.

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