How the 2021 hurricane season, matched up to my outlook.

 

The winter upper-level weather pattern is becoming well established. So, it’s time to put the summer and fall behind us.

Even through the official 2021 Atlantic Hurricane Season doesn’t end until November 30th, the tropics are quiet and another named storm is looking unlikely. So, I wanted to go over how the season basically went and how it compared to the hurricane outlook I released back in May.

The 2020 hurricane season:

First let’s look back that the statistics for 2020. Last year, saw the most active Atlantic hurricane season in recorded history, with a total of 31 tropical cyclones, 30 named storms, 13 hurricanes, and 6 major hurricanes. There were 11 storms that made landfall in the United States. The majority of those made landfall in the Gulf of Mexico with three of them passing through Arkansas. 2020 had the 2^nd highest seasonal ACE in Recorded history, 2^nd only to 1933. The season broke numerus records.

My call for 2021:

Named Storms 18-26, Hurricanes 6-13, Major hurricanes 3-6, U.S. landfalling tropical cyclones of 6-10. I called for an Accumulated Cyclone Energy (ACE) value of 140-190. In the Outlook I also said the Northeast was at a heightened risk for tropical cyclone impacts.

As of right now, the 2021 Atlantic hurricane season has seen 21 named storms, seven of which were hurricanes (Elsa, Grace, Henri, Ida, Larry, Nicolas and Sam).  The season had Four major hurricanes (Grace, Ida, Larry and Sam). Eight landfalling U.S. named storms. Ace is standing at 145.1, as of 18:00 UTC November 7.

The northeast had direct impacts from 4 named storms: Elsa, Fred, Henri, Ida. Henri made landfall on August 22, near Westerly, Rhode Island.

So, the season did fall within all the parameters I set back in the spring.

 A quick look at the 2021 season:

The beginning of the season started busy. While not as early as last year’s first storm, Arthur, Ana marked another early start to the Atlantic hurricane season, forming northeast of Bermuda on May 22. There were four named storms that formed in the month of June. The Atlantic Basin then shutdown for July, when no new storms formed. August saw the tropical Atlantic wake back up leading to five named storms forming. August included Major Hurricane Ida; she became a Category 4 borderline 5 and made landfall in the Louisiana.  Ida caused 115 deaths and more then $65 billion in damage. September is historically the busiest month of the hurricane season; that was surely the case this year. Nine named storms formed. Six of the nine storms only reached tropical storm strength. Stronger storms included Nicholas, Larry, and Sam. Sam was the most powerful hurricane of the season, reaching category four status with winds sustained at 155+ mph; I think Sam made it to Category 5, but that isn’t official. Luckily Sam made no landfall and eventually dissipated over the north Atlantic. November has had only one named storm so far. Tropical storm Wanda formed over the north Atlantic and dissipated a few days later.

Overall, the 2021 hurricane season was over active. But the intensity of the storms ended up being closer to average.  This year saw the entire official name list used. Making 2021 only the third time on record, behind the 30 named storms of 2020 and 2005’s 28 named storms that this has occurred. While we had 21 named storms, The ACE was only 145.1. ACE is the only true measure of a season’s activity. Most of the storms that formed this season were weak extremely short-lived storms.  Of the 21 storms, Larry and Sam made up the bulk of this season’s total ACE.   

I’ve seen the main stream media going on and on about how active this season was, I’ve seen some reports that said this is the 3^rd most active Atlantic Hurricane Season on record.

But is that really true?

The most active Atlantic Hurricane Seasons based on named storms.

Rank   Year    Number of Storms

1.        2020 … 30

2.        2005 … 28

3.        2021 … 21

4.        1933 … 20

5.        2012 … 19

6.        2011 … 19

7.        2010 … 19

8.        1995 … 19

9.        1887 … 19

10.      1969 … 18

11.      2008 … 16

12.      2003 … 16

13.      1936 … 16

14.      2007 … 15

15.      2004 … 15

16.      2001 … 15

17.      2000 … 15

 

The active Atlantic Hurricane Seasons based on ACE.

1933 … 258.57

2005 … 250.1275

1893 … 231.1475

1926 … 229.5575

1995 … 227.1025

2004 … 226.88

2017 … 224.8775

1950 … 211.2825

1961 … 205.395

1998 … 181.7675

1887 … 181.26

1878… 180.85

2020 … 180.3725

2003 … 176.84

1999 … 176.5275

1964 … 169.7675

1932 … 169.6625

1996 … 166.1825

1886… 166.165

1969 … 165.7375

2010 … 165.4825

1906… 162.88

1955 … 158.17

1899 … 151.025

1980 … 148.9375

2008 … 145.7175

1966 … 145.2175

2021 … 145.1

 

Most people think of a hurricane season's activity based on the number of named storms. While that is a good metric to use, a season's true activity is measured by ACE.

ACE is a measurement of a hurricane season based on each storm's intensity and how long it lasts. Its calculation is a little cumbersome but it gives the best indicator of activity. is generally used to measure the combined duration and strength of tropical cyclones. It is also a good metric for scientists to compare storms against each other and across different seasons.

 ACE is calculated by squaring the storms wind speed in knots at six-hour intervals (advisory issue times), then divided by 10,000. For example, a 35-knot (40 mph) tropical storm for one advisory would have an ACE of 0.1225.

 So, while this hurricane season’s 21 named storms, places it 3^rd on the list of named storms. It is only listed at 28 based on ACE. So, in spite of what several media outlets are pushing; it wasn’t really super active.