October Not Over 2020 Hurricane Summary

2 11 2020

Dale C. S. Destin|

The hurricane season was certainly not over in October. There was a record-tying number of major hurricanes – two, Delta and Epsilon; this represents over 665 percent of average (normal). The number of named storms – five, was 250 percent of average. Further, the number of hurricanes – four, was over 360 percent of average.

October Not Over 2020 Summary. Note, although Eta became a storm in November it is credited to October to which it owes its origin, according to the international standard

October 2020 is only the fifth October on record with two major hurricanes. The last time there were two major hurricanes in October was 2005. The month averages a major hurricane once every three to four years. Previous years with two major hurricanes are 2005, 2001, 1950 and 1894.

It was a very active October. The metric that speaks more completely to the activity of a month or a hurricane season is called the accumulated cyclone energy (ACE) index. Normally, the month produces an ACE index of 14.5 – that was more than doubled for this October – 39.2. Compared with the activity for September, although it was a record-setting month regarding named storms, the ACE index of 63 was only 1.23 the average – 51.4. Hence, October was more active relative to itself than September was.

Using the ACE index metric, this October was more active that 28 previous full hurricane seasons of 169, including the 2013 season, which had 14 named storms but an ACE of 36. Also, the two major hurricanes during the month were more than or equal to 125 full seasons. We would have also seen more or the same number of hurricanes than 71 full seasons, including 2015.

Every named storm in October was earlier than those with the same names that formed during October of the 2005 hurricane season, which is the only other season with more than 20 named storms, on record. The records were broken by as many as 41 days. This may be an omen for this season setting a record for the highest number of named storms.

Thankfully, none of these storms threatened Antigua and Barbuda and the rest of the Eastern Caribbean. The most we got were moderate to large swells from Epsilon along with minimal showers from a few very weak feeder bands. The rest of the Caribbean Islands fared well also with none experiencing storm or hurricane conditions. Delta was a relatively close call for Jamaica, the Cayman Islands and Cuba.

We are through the season, except for one more month, officially – November. Thus far, there have been 28 named storms – the most through October and tied with 2005 for the most on record, for a season. The 2005 record is now expected to be broken. There have also been 11 hurricanes of which 4 were major hurricanes – Category 3 or over.

2020 Atlantic hurricane season summary map.png

Recall that an average season produces 12 named storms, 6 hurricanes and 3 major hurricanes. Thus, this season has produced, thus far, 233 percent of average number of named storms, 183 percent of average number of hurricanes and 133 percent average number of major hurricanes.

Notwithstanding the record number of named storms, the season is very far from being a record active one. Recall that the activity of a season is based on the ACE index. The ACE index, thus far for 2020, is 143.9; this is only 136 percent of the average – 105.5.

This season is not even ranked in the top 20 with respect to ACE. It is currently at 27th and is unlikely to reach the top 10. The ACE index for a season is also a measure of the potential destructiveness of the collective named storms. This means that although 2020 has produced a record number of storms, there are several seasons that were potentially more destructive, including the 2017 season with and ACE index of 223.

Top 20 Most Active Atlantic Hurricane Season. TS – Tropical Storms; HU – Hurricanes; MH – Major Hurricanes. Credit Wikipedia.

The most active season on record, using the ACE index metric, remains 1933, with an index of 259, produced by “just” 20 named storms. This is nine more ACE than the 2005 season, which had eight (40 percent) more named storms.  

Delta – 5 to 11 October, became the record-tying fourth named storm of 2020 to strike Louisiana, as well as the record-breaking 10th named storm to strike the United States. It was a very destructive Category 4 hurricane with 1-minute peak sustained winds of 230 km/h (145 mph). It caused, at least, US$2 billion in damage and killed 6 people. It also affected Jamaica, the Cayman Islands, The Yucatán Peninsula, the Gulf Coast, Southeastern and Northeastern United States.  

Hurricane Delta, Across the Western Caribbean Sea – Oct 6, 2020

Epsilon – 19 to 26 October, impacted Bermuda minimally, passing about 190 to its east. It had peak sustained winds of 185 km/h (115 mph), making it a Category 3 hurricane. Exact damage to date is unknown but it generated moderate to large swells across most Atlantic coastlines of the Caribbean, the Bahamas, the United States and Canada.

Hurricane Epsilon, Passing Northeast of Bermuda, Oct 23, 2020

Zeta – 24 to 30 October, became the record-tying sixth hurricane to make landfall on the United states in one year. It was also the record fifth named storm to make landfall on Louisiana in one year. Zeta had peak 1-minute sustained winds of 175 km/h (110 mph) and caused eight fatalities and over US$13.7 million in damage across Jamaica alone. It also impacted the Cayman Islands, Central America, the Yucatán Peninsula and the Mid-Atlantic United States.  

Hurricane Zeta Across the Western Caribbean Sea – Oct 26, 2020

Eta – 31 October to present, became the record-tying 28th named storm for the year, placing 2020 level with 2005 for highest number of named storms. Eta is currently a Category 1 hurricane with the potential to reach Category 3 intensity. It is an extreme threat to Nicaragua and Honduras with the potential to cause Catastrophic damage.

Hurricane Eta Across the Western Caribbean Seas – Nov 2, 2020

The month also produced Tropical Storm Gamma – 2 to 6 October. Gamma made landfall on the Yucatán Peninsula with peak 1-minute sustained winds of 110 km/h (70 mph), killing 7 with the damage amount presently unknown.  

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