The 2020 Atlantic Hurricane Season Was a Record Breaker
JAMES H. RUPPERT JR.
The 2020 Atlantic hurricane season was a record-breaker, and it’s raising more concerns about climate change.
It was clear before the 2020 Atlantic hurricane season started that it was
going to be busy
. Six months later, we’re looking back at a
trail of broken records
, and the storms may still not be over even though the season officially ended on Nov. 30.
This season had the most named storms, with 30, taking the record from the calamitous 2005 season that brought
to New Orleans. It was only the second time the
list of storm names
was exhausted since naming began in the 1950s.
Ten storms underwent
, a number not seen since 1995. Twelve made landfall in the U.S., also setting a
. Six of those landfalling storms were hurricane strength, tying yet another record.
Ironically, cooling in the equatorial Pacific makes it easier for tropical storms to form and gain strength in the Atlantic. That’s because La Niña weakens the vertical wind shear over the tropical Atlantic. Vertical wind shear – a change in wind speeds with altitude – is highly disruptive to storm development.
As the La Niña pattern became established this season, it made the tropical Atlantic much more hospitable for storms to form and intensify.
The second critical factor was the extremely warm temperatures in the Atlantic, including the Gulf of Mexico and the Caribbean.
Hurricanes are powered by the transfer of heat from the ocean to the atmosphere. The sea surface temperature therefore dictates the maximum
a storm can attain under perfect conditions – it’s like a thermodynamic “speed limit” on hurricane intensity.
The sea surface temperature approached
in the Atlantic hurricane basin this season, including in September, the most active Atlantic storm month on record.
What does climate change have to do with it?
An important part of this season’s story is the Atlantic warming trend we’re witnessing, which is
going back at least several millennia.
much of the excess heat trapped by greenhouse gases. With greenhouse gas concentrations
due to human activities, such as the burning of fossil fuels, average sea surface temperatures are
to continue rising over the coming decades.
Whether climate change caused the extremely high number of storms this season is unclear. There is
no detectable trend
in global hurricane frequency, and computer modeling studies have had
However, the warming climate is increasing the threat posed by hurricanes in other ways.
Ten storms this season underwent rapid intensification – a 35 mph increase in maximum winds within 24 hours. Rapidly intensifying storms are especially dangerous because 1) they are challenging to
predict, and 2) they provide minimal time for evacuations when they intensify just before making landfall.
and Sally both rapidly intensified just before making landfall on the Gulf Coast this season. Eta rapidly intensified to a Category 4 just before hitting Nicaragua, and just two weeks later, Iota essentially repeated the act in the same location.
Forecasts for the tracks or paths of tropical cyclones have
in recent decades, as much as five days in advance. However, forecasts of storm formation and intensification have improved
The complexity of weather models makes this a daunting challenge. However, it becomes more tractable as researchers learn more about how hurricanes form and intensify and identify the root causes for
in computer model predictions.
explores how clouds create their own greenhouse effect, trapping heat that causes hurricanes to form and intensify more quickly. Improving how numerical models account for this cloud feedback may ultimately hold promise for more accurate forecasts. Innovative ways of collecting
in developing storms, down to their
, will also be necessary for guiding these improvements.
in high-intensity storms, the risks from these storms will only grow. The ability to accurately predict how and when they will form, intensify and threaten coastal populations is crucial.
This article has been updated with the season ending and NOAA video of 2020’s Atlantic storms.
AUTHOR: JAMES H. RUPPERT JR.
DATE: NOVEMBER 30TH, 2020
BIO: Assistant Research Professor, Penn State - Allison Wing Assistant Professor of Meteorology, Florida State University