Only Category 5 hurricane of 2020 downgraded in new report
By
Brian Lada, AccuWeather meteorologist
Updated May 19, 2021 9:24 PM EDT
The last storm of the hyperactive 2020 Atlantic hurricane season was also the strongest of the season, initially rated as a rare Category 5 on the Saffir-Simpson hurricane wind scale, but a new report found that it was not quite as powerful as previously thought.
Every year after the Atlantic hurricane season wraps up, the National Hurricane Center (NHC) re-analyzes all of the data gathered about every single storm to create detailed reports about each system.
On Tuesday, May 18, the NHC released the final tropical cyclone report of the 2020 season that detailed the life of Iota and made a small, but significant change to the storm’s peak intensity.
As Iota was barreling toward Nicaragua, where it eventually made landfall on Nov. 17, the NHC initially said that it had briefly reached Category 5 status, the highest rating for a hurricane on the Saffir-Simpson scale.
To be considered a Category 5 storm on this scale, sustained winds need to be at least 157 mph.
One of the tools that the NHC uses to estimate the wind speeds of a hurricane is a remote sensor on the Hurricane Hunters' aircraft called SFMR (stepped frequency microwave radiometer), which estimates the wind speed at the surface.
This satellite image made available by NOAA shows Hurricane Iota in the North Atlantic Ocean on Monday, Nov. 16, 2020, at 07:11 EST. (NOAA via AP)
During one of the flights through the eye of Iota when it was around peak strength, this instrument registered winds of over 160 mph (140 knots).
However, the NHC said in the post-storm analysis that this estimate was high, so the maximum winds were lowered by 5 mph to around 155 mph (135 knots).
“While a 5-knot change is typical for post-analysis best track intensity changes, this decrease in Iota’s peak intensity crosses the threshold from Category 5 to Category 4,” the NHC said in the report. “This change is well within the typical range of uncertainty in NHC’s post-storm intensity analyses.”
In this photo taken Friday, May 12, 2017, senior hurricane specialist Dan Brown, talks to a reporter at the U.S. Coast Guard Air Station Miami, at the Miami-Opa Locka Executive Airport, in Opa-locka, Fla. Standing in front of a NOAA Lockheed WP-3D Orion N42RF Hurricane Hunter, Brown said, it's difficult to measure what's happening around a hurricane's eye where the strongest winds swirl or how it interacts with the ocean and the atmosphere, and that affects the accuracy of storm intensity forecast. (AP Photo/Alan Diaz)
Iota being downgraded from a Category 5 hurricane to a Category 4 hurricane means that there were no Category 5 storms in the Atlantic basin during the 2020 season.
This change also ends the record streak of consecutive years with a Category 5 hurricane in the Atlantic basin, which started in 2016 with Hurricane Matthew and now ends in 2019 with Hurricane Lorenzo.
This four-year streak is still the longest on record for the Atlantic basin, followed by three consecutive years with a Category 5 hurricane from 2003 through 2005.
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Last week, the NHC made another post-season change to the 2020 season when it upgraded Hurricane Zeta to a Category 3 storm, the threshold needed to be considered a major hurricane.
Unlike Iota, for which the NHC decreased peak winds by 5 mph, the NHC increased Zeta’s peak winds by 5 mph. This small adjustment made Zeta the seventh major hurricane of the season, which ties the 2005 season for having the highest number of major hurricanes.
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News / Hurricane
Only Category 5 hurricane of 2020 downgraded in new report
By Brian Lada, AccuWeather meteorologist
Updated May 19, 2021 9:24 PM EDT
The last storm of the hyperactive 2020 Atlantic hurricane season was also the strongest of the season, initially rated as a rare Category 5 on the Saffir-Simpson hurricane wind scale, but a new report found that it was not quite as powerful as previously thought.
Every year after the Atlantic hurricane season wraps up, the National Hurricane Center (NHC) re-analyzes all of the data gathered about every single storm to create detailed reports about each system.
On Tuesday, May 18, the NHC released the final tropical cyclone report of the 2020 season that detailed the life of Iota and made a small, but significant change to the storm’s peak intensity.
As Iota was barreling toward Nicaragua, where it eventually made landfall on Nov. 17, the NHC initially said that it had briefly reached Category 5 status, the highest rating for a hurricane on the Saffir-Simpson scale.
To be considered a Category 5 storm on this scale, sustained winds need to be at least 157 mph.
One of the tools that the NHC uses to estimate the wind speeds of a hurricane is a remote sensor on the Hurricane Hunters' aircraft called SFMR (stepped frequency microwave radiometer), which estimates the wind speed at the surface.
This satellite image made available by NOAA shows Hurricane Iota in the North Atlantic Ocean on Monday, Nov. 16, 2020, at 07:11 EST. (NOAA via AP)
During one of the flights through the eye of Iota when it was around peak strength, this instrument registered winds of over 160 mph (140 knots).
However, the NHC said in the post-storm analysis that this estimate was high, so the maximum winds were lowered by 5 mph to around 155 mph (135 knots).
“While a 5-knot change is typical for post-analysis best track intensity changes, this decrease in Iota’s peak intensity crosses the threshold from Category 5 to Category 4,” the NHC said in the report. “This change is well within the typical range of uncertainty in NHC’s post-storm intensity analyses.”
In this photo taken Friday, May 12, 2017, senior hurricane specialist Dan Brown, talks to a reporter at the U.S. Coast Guard Air Station Miami, at the Miami-Opa Locka Executive Airport, in Opa-locka, Fla. Standing in front of a NOAA Lockheed WP-3D Orion N42RF Hurricane Hunter, Brown said, it's difficult to measure what's happening around a hurricane's eye where the strongest winds swirl or how it interacts with the ocean and the atmosphere, and that affects the accuracy of storm intensity forecast. (AP Photo/Alan Diaz)
Iota being downgraded from a Category 5 hurricane to a Category 4 hurricane means that there were no Category 5 storms in the Atlantic basin during the 2020 season.
This change also ends the record streak of consecutive years with a Category 5 hurricane in the Atlantic basin, which started in 2016 with Hurricane Matthew and now ends in 2019 with Hurricane Lorenzo.
This four-year streak is still the longest on record for the Atlantic basin, followed by three consecutive years with a Category 5 hurricane from 2003 through 2005.
CLICK HERE FOR THE FREE ACCUWEATHER APP
Last week, the NHC made another post-season change to the 2020 season when it upgraded Hurricane Zeta to a Category 3 storm, the threshold needed to be considered a major hurricane.
Unlike Iota, for which the NHC decreased peak winds by 5 mph, the NHC increased Zeta’s peak winds by 5 mph. This small adjustment made Zeta the seventh major hurricane of the season, which ties the 2005 season for having the highest number of major hurricanes.
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Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier, Spectrum, FuboTV, Philo, and Verizon Fios.
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