Joe D’Aleo CCM, Weatherbell.com
The 2020 hurricane season in the Atlantic Basin is the most active in history with 30 named storms, breaking the previous record of 2005 (28). 6 storms were major storms including iota and set a record for the most recent major hurricane.
The Gulf and Central America were badly affected and were reminiscent of the period from 1988 to 1900 (see).
Despite the busy Atlantic, the Pacific was calm and the hemisphere as a whole had a quieter than the normal season (80% of the normal season).
The ACE of 179.8 ranks 13th behind 2017 and 2005 and the peak year 1933.
An active season was expected – several factors indicated this. LA NINA AND LOW SCISSORS IN THE ATLANTIC
We have a La Nina.
Gerry Bell showed how La Ninas creates fewer storms in the east Pacific and less shear in the east, which favors more Atlantic storms.
Mild eastern shear is observed in the main developing region and the Caribbean, consistent with continued suppression of La Nina Pacific.
2017 was a no-shear year with a much higher ACE (7th place with
224.9 compared to 179.8 in 2020). Strong western shear was observed from 2014 to 2016.
The pressure anomalies reflect the low pressure and storm marks under the 40N crest.
WARM ATLANTIC MODE OF THE AMO
The Atlantic is warm.
Unsurprisingly, the warm Atlantic creates more storms.
In the above figure, the red columns represent the seasonal AMO and the black lines the number of storms with Atlantic names
LOW SOLAR AND COLD HIGH ATMOSPHERE
Hodges and Elsner (FSU) found that low insolation resulted in a colder atmosphere, which encouraged more instability and possibly stronger storms.
In fact, review the 100MB temperature anomalies in the Atlantic Basin including the Caribbean since July.
So we had the “perfect storm” in the Atlantic basin with a La Nina that resulted in low vertical shear. The AMO’s warm mode provided more thermal energy and little solar energy, resulting in a colder atmosphere and greater instability. Despite the large number of storms and 6 majors, the ACE index is still lagging behind years like 2017 and 2005 and 10 others.
Not every meteorologist believes that 2020 holds the record for most of the storms mentioned. With advances in technology, forecasters can identify smaller subtropical storms that may have gone unnoticed in the past.
“Now, if you want to make a fair comparison between storms and past storms, you have to be really careful about how you interpret the raw number,” said Christopher Landsea, director of tropical analysis and forecasting at the National Hurricane Center. said according to the New York Times. “There was a lot of hype about the record number of storms and yes, it was a busy year. There were terrible effects. But is that really a record? The answer is no. “
ACE supports that. And the decadal trend towards hurricanes and major hurricanes has subsided.
Weatherbell’s Hurricane Chief Guru Joe Bastardi commented on the season.
Summary of the tropical season of the N Hemisphere
- Yes, most of the aforementioned storms in the Atlantic. Weatherbell undercut the total number of names
- Yes, year with the highest impact on the US coast (no surprise as we did a big deal from April)
- ACE at 180 in our ACE range from March! 13th highest on recordBTW another miserable year from the Euro models. We released this ACE in March. At the time, the euro was forecasting 80% of the average
- This is where it gets interesting: ACE / Storm was 6 in the DEAD LAST ranking in last place up to ACE / Storm. How bad was it? THE AVERAGE ACE / STORM for the other 21 seasons was 12! The next year that year was another mega-year in 2005, but that was a respectable 9
The obvious conclusion is twofold,
- Some of them should not have been named or would not have been named in previous years. Well, if you don’t want to accept that, it means more storms but weaker. It’s absolutely amazing to see that the ace / storm is HALF the average of all the other samples. But it gets worse as far as the hype goes:
- Totally ignoring the lack of activity in the Pacific Basin and around the world.
I keep hearing this globally and globally that, which of course only applies if you ignore the fact that the number one area for ACE (Pacific) was so far below the normal West Pacific, 52%, the East Pacific 56%.
The total ACE between the two is usually 426. This year it was 226 so far. So the basin that is 4 times the normal value of the Atlantic is only 50% of its normal value! For the northern hemisphere was 80% of normal. So also with the hyperatlantic season.
GLOBAL we were below average.
So there is no question that the Western Hemisphere Impact is huge record business and should be talked about. However, if you want perspective and a bigger picture there are many reasons to counter the idea that this is an example of some type of atmospheric apocalypse but you have to look and when you do you will see it on the other Side of the coin has a lot to tell.
Of course, the coin tossed today when it comes to advancing ideas always seems to be going in one direction.