There are still several months left until the official end of hurricane season 2020, but there has already been twice the average number of storms. With 23 storms under the belt, the traditional hurricane names are used. We are moving into the Greek alphabet. Alpha and Beta formed on Friday, but more is on the way!

What makes this season being so extreme and record-breaking, is the fact that storms with the same letters are developing weeks earlier than normally expected. And even much earlier than previously set records.

Such satellite image of numerous active storms is almost typical for 2020. While there was very active Tropical Atlantic not enough, even the Mediterranean produced a tropical storm – Medicane Ianos! Seriously.

Let’s get into some more details…

Atlantic remains very warm

 

As it has been throughout the most of this summer, much above normal temperatures of sea waters across the Atlantic, the Caribbean, and the Gulf of Mexico are observed.

Sea temperatures across the Western Atlantic, the Caribbean, and the Gulf are very hot – nearly 29-31 °C. While the temperatures across the Eastern and Central Atlantic are also very warm, roughly 27-29 °C.

This means that the temperatures are around 1-2 degrees Celsius warmer than the long-term average (1981-2010) across the Western Atlantic, Caribbean, and also in part of the Gulf. Seas are particularly warm along the US East Coast, even up to 3 °C warmer.

Above normal sea temperatures are also over the Eastern Atlantic and around Cabo Verde, where tropical waves typically begin intensifying as they eject from West Africa.

Therefore, the oceanic conditions across the Caribbean and Western Atlantic seem to remain strongly supportive of good sources for storms with any waves or tropical systems in the coming weeks.

The Caribbean could get busy in the near future

 

What we have seen through the past several weeks, was the result of increasing potential for storm development. We have discussed this potential in several of our threads back in August, as the significant Madden-Julian Oscillation (MJO) became very favorable for the Atlantic tropical activity.

The atmospheric Kelvin wave was moving into the Atlantic and strongly boosted the activity.

The latest model forecast for MJO suggests the Eastern and Central Atlantic might finally see some relief in activity through the remainder of September. The environmental conditions are becoming less supportive of tropical development, as upper-level convergence spreads. Normally it tends to suppress activity.

But conditions over the Western Atlantic, the Caribbean, and into the Eastern Pacific Ocean should begin improving towards the end of September and into early October. The upper-level divergence arrives aloft.

Therefore this tropical region, roughly between 60 °W and 150 °W, will be monitored for increasing activity soon.

Attached is the atmospheric rivers of precipitable water (PWAT) forecast across the Atlantic Ocean, with a tropical storm moisture support towards the Caribbean region.

ACE index – Accumulated Cyclone Energy

 

Accumulated cyclone energy (ACE) is a metric used to express the energy used by a tropical cyclone during its lifetime. The calculation takes a tropical cyclone’s maximum sustained winds every six hours and multiplies it by itself to generate the values.

The total sum of these values is calculated to get the total for a storm and can either be divided by 10,000 to make them more manageable or added to other totals in order to work out a total for a particular group of storms.

Statistical data as of Sept 17th, though. Produced by Dr. Philip Klotzbach, the Meteorologist at CSU specializing in Atlantic basin seasonal hurricane forecasts.

The calculation was originally created by William Gray and his associates at Colorado State University as the Hurricane Destruction Potential index, which took each hurricane’s maximum sustained winds above 65 knots (120 km/h = 75 mph) and multiplied it by itself every six hours.

This index was subsequently tweaked by the NOAA in 2000 so it includes all tropical cyclones, with winds above 35 knots (65 km/h = 40 mph) and renamed to Accumulated Cyclone Energy.

Within the Atlantic Ocean, the NOAA uses the ACE index to classify hurricane seasons into four categories.

  • extremely active season – ACE index above 152.5
  • above-average season – ACE index above 111
  • near-average season – ACE index between 66 and 111
  • below-normal average season – ACE index below 66
ACE index in 2020 hurricane season

 
In 2020, the North Atlantic has already generated an ACE index of 88.6 as of Sept 19th. This means the activity is roughly 33 percent above the long-term average for the season by this date.

The biggest contributors to the index so far were obviously the most violent hurricanes – Teddy (15.6), Paulette (15.0), and Laura (12.8). Followed by Isaias (9.2) and Sally (7.4).

Climatologically, the sum of ACE at the end of an average hurricane season is around 105. With the currently ongoing storms and future trends, it is very likely the index will end up pretty much above the average.

Ongoing storms

 

Tropical Atlantic remains active lately, with several storms ongoing.

Tropical Storm Wilfred

 

While the Gulf was on focus to get the potentially last named storm for the 2020’s list (it would have been Wilfred), it was beaten by not only one, but two systems just hours earlier. A Tropical Storm Wilfred has formed in the Eastern Atlantic on Friday afternoon, Sept 18th.

Wilfred was the last name of the 2020 Atlantic hurricane season. It broke the all-time record as the earliest Atlantic 21st named storm formation. The previous record-holder was Vince, forming on Oct 8th, 2005.

Subtropical storm Alpha

 

Soon after, a subtropical storm Alpha formed near Portugal. There was a small low-pressure area that has been rotating around a larger extratropical low in the far northeastern Atlantic.

Tropical Storm Beta

 

And it didn’t last long, the tropical activity over the Gulf of Mexico finally formed a Tropical Storm Beta.

Beta is the 10th Atlantic named storm to form so far this month. This sets the new record for the most named storms for any September. The previous September record for Atlantic named storm formations was 8, set in 2002, 2007, and 2010.

All together, this also means that Sept 18th, 2020 has seen three Atlantic named storms forming – Wilfred, Alpha, and Beta. This is the first time in the modern era that three storms have formed in one day!

The only other time on record that the Atlantic had 3 named storm formations on the same calendar day was August 15, 1893.

Major hurricane Teddy

 

The most intense currently ongoing storm is now a Category 3 hurricane Teddy in western Atlantic. It’s on the way to pass very near Bermuda on Monday.

Visible satellite of exploding hurricane Teddy. Graphics: Windy.com

Hurricane Teddy will then continue generally northward towards Canada where a potentially hurricane-strength landfall is possible by mid next week.

But wait, there is more…

Just two days ago, there was a medicane Ianos ongoing in the Mediterranean, Europe. Medicanes are Tropical-like cyclones (TLC) in the Mediterranean and they are sometimes also called Mediterranean cyclones or Mediterranean hurricanes. These are cyclones with subtropical and tropical characteristics, that form in the Mediterranean region.

Ianos brought destructive winds and flooding into Greece and was one of the strongest Mediterranean tropical storms on record!

Medicane Ianos over the Ionian Sea. Graphics: Windy.com

Record-breaking 2020 season

 

As predicted by NOAA forecasters back in early July this year, the above-average season was expected in 2020.

But following the season’s evolution through the past two months, we could see the 2020 Atlantic hurricane season is extremely active and setting a record after record with almost every storm.

2020 Atlantic season has already used all the regular list of storm names. The list was finished on Sept 18th. The last and the only time this happened, was in 2005.

If this happens, the Greek alphabet is used for future storms.

For instance, there were five tropical systems over the Atlantic basin (Paulette, Rene, Sally, Teddy, and Vicky) on Sept 14th. This tied the record for the most number of tropical cyclones in that basin at one time, the last set in September 1971.

The 2020 Atlantic hurricane season has generated 23 named storms. On average through Sept 18th, the Atlantic has had 8 named storms.

Hurricane season 2020 list

 

Here is the list of all tropical storms/hurricane so far in the Atlantic 2020 hurricane season:

Hurricane season 2020 Greek alphabet list

 

The list above was 21 storm systems with the regular storm names. Now the Greek alphabet has already use the first two letters:

It might not last long, as there are two more tropical waves with the potential to be upgraded into Tropical Storms strength in the coming days. The next names are Gamma and Delta.


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Tropical Cyclone Naming

 

A rotating list of names is used, the list repeats every six years. For example, the list of 2020 will again be used in the year 2026. Male and female names are alternated in the list.

For the Atlantic Basin during the 2020 hurricane season, there were 21 names reserved to be used for tropical systems.

All were used already, the list was completed by Sept 18th as a letter ‘W’ was used by Tropical Storm Wilfred in the Eastern Atlantic.

If hurricanes develop historic levels, becomes particularly deadly or costly to life and property, its name is retired. Retired names, if any, will be announced by the World Meteorological Organization (WMO) in the spring of 2021.

The retired name is then replaced by another one.

Names simplify user communication

 

The naming of the tropical storms is used with one main reason – to help in the quick identification of storms in warning messages.

Systems having a certain name are presumed to be much easier to remember than numbers and other more technical terms. It is also easier for the general media to report on tropical systems forming, so the warning messages with storm names are straightforward information.

This, at the end, increases public awareness which is the most important.

The advantages of the storm names are quite important in exchanging detailed information about the ongoing systems between various users, including coastal bases, and ships traveling at the sea.

Alphabetical order of storms

 

To have the most out of a storm naming system, NOAA meteorologists decided to create a list of names arranged alphabetically.

Therefore, a storm with a name that begins with a letter ‘A’, as Arthur in 2020, would be the first storm to occur in the year. The last letter is ‘W’, therefore Wilfred for the ongoing season.

The list of storm names covers only 21 letters of the alphabet. The letters Q, U, X, Y, and Z are not used, since it is difficult to find six suitable names. As indeed, for the instantly recognizable events, names have to be easy to read, write, and remember.

The Atlantic tropical storms have been named from lists originated by the National Hurricane Center, started in 1953. Nowadays, the names are maintained and updated by an international committee of the World Meteorological Organization (WMO).

Infamous, retired storm names

 

If a storm or a hurricane reaches a deadly or costly ‘status’, the list gets some changes. A new name is then used, replacing the retired letter from the list. One of the main reasons to use different names is also the fact it would be inappropriate for reasons of sensitivity since that retired storm brought significant damage and casualties.

These are the infamous storm names which have brought particularly severe damage and loss of life:

typhoon Mangkhut (the Philippines, 2018),
– hurricanes Irma and Maria (the Caribbean, 2017),
typhoon Haiyan (Philippines, 2013),
– hurricane Sandy (the USA, 2012),
– hurricanes Katrina, Rita, Wilma (the USA, 2005)
– …

Katrina, for example, was replaced with Katia when the list cycled back in 2011.

89 storm names have been retired and replaced by new names set by the World Meteorological Organization (WMO) since 1954.

Use of Greek alphabet

 

When a very active Atlantic hurricane season occurs and all the names are used, the Greek alphabet is used. This has only occurred once since 1953, exactly 15 years ago (2005). But here we are, the 2020 season is the second one to use the Greek alphabet.

Hurricane season 2005 was a record-breaking year which has produced a few destructive hurricanes, e.g. Katrina, Rita, and Wilma, whose names were all retired. Six (6) names were used, where the last-named storm was Zeta. It formed on Dec 30th.

The Greek alphabet starts with Alpha, Beta, Gamma, etc. So far, 2020 has used Alpha and Beta, both Tropical Storms formed on Sept 18th.

Back in 2006, it was discussed that the use of the Greek alphabet naming will remain also if there are any destructive hurricanes coming. The WMO hurricane committee decided that as the Greek Alphabet was not expected to be frequently used.

Therefore, the decision was made that the list remains unchanged and that the Greek alphabet would continue to be used.

So, what’s next?

 
There will surely be new storms coming in the following weeks, so the Greek alphabet list use will continue.

In the typical, average hurricane season, there are around five to six named storms likely to occur from Sept 19th until the official end of the season (Nov 30th). Around three to four of them become hurricanes, and one or two become major (Category 3+) hurricanes.

This means the average season would take us approximately through Theta in the Greek alphabet list before the season is over.

That would be for the average season. But taking into account that the 2020 hurricane season is so extremely active, there are quite high chances the number of storms through the rest of the season might be even higher.

For example, the only hurricane season using the Greek alphabet, 2005, had eleven (yes, 11) additional storms after Sept 19th. If something similar happens in this season, that would bring us towards the Greek letter Nu or Xi.

Can we see more than 30 storms this year?

 
If 2020 season reach at least Iota letter for a storm name, that would be 30 storms in total. But if indeed 11 more storms form, than it is more than halfway through the Greek alphabet list.

And would mean the season would have a total of 34 storms at the end. Exceptional to say at least – that is triple the average number for one normal season!

But let’s wait and see how the future weeks evolve. Although the oceanic and environmental seem further supportive of tropical development, there is indeed no guarantee of what will happen.

Our team will continue covering the forthcoming tropical events and will keep you updated. Autumn months sometimes also bring tropical storms (or even hurricanes) close to Europe.

Enjoy the weather and stay tuned!

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