When Tropical Storm Zeta formed early Sunday morning south of western Cuba, it put the 2020 hurricane season in the record books as only the second year in history to see 27 named storms. It also became the earliest 27th North Atlantic tropical or subtropical storm on record, surpassing the old mark of November 29, set by Hurricane Epsilon in 2005. The last and only other storm named Zeta was in 2005, when a system developed on December 30, a month after the official end of hurricane season, and lingered into the first week of 2006. If there is a record-breaking next named storm in 2020, it would be assigned Eta from the Greek Alphabet.
With 27 named storms, this season is the second most active North Atlantic hurricane season on record, behind only the 2005 hurricane season. It is also only the second tropical cyclone season to feature the Greek letter storm naming system, with the other season also being 2005. The last name in the “2020 North Atlantic hurricane season name list” was used when Tropical Storm Wilfred officially formed in the eastern North Atlantic as the earliest “W” named storm on record at the National Hurricane Center (NHC). Soon after, the NHC ventured somewhere it has only had to go once before – the Greek Alphabet – as Subtropical Storm Alpha of 2020 formed off the coast of Portugal, and the doubled down Tropical Storm Beta of 2020 in the Gulf of Mexico forming in September. Wilfred was the final named storm of 2020 hurricane season’s alphabetic name list, forcing hurricane specialists to begin using letters from the Greek Alphabet for future storms – something that has only happened once before in 2005 in the North Atlantic and never in the Pacific. There was a total of 27 named storms and one unnamed storm that year, which required the NHC to go six letters deep into the Greek Alphabet. I must note here that before the 2005 North Atlantic hurricane season, the Greek Alphabet was used in the early 1970s, but they were not truly tropical in nature. For example, there was Subtropical Storm Alpha of 1972, which briefly threatened Cape Cod but stayed out to sea. In 1972 and 1973, the International Phonetic Alphabet was used to name subtropical storms: Alpha, Bravo, Charlie, Delta, Echo, etc. Four were named in 1972 and two in 1973, then that plan was abandoned for no apparent reason.
There is a little-known fact about the Greek Alphabet that most meteorologists, international and local, don’t realize or know about, and that is the fact that the Region IV (consisting of the countries of Bermuda, North and Central America, The Bahamas and the Caribbean) hurricane naming committee in the spring of 2006 faced a similar dilemma that first occurred back in 1950 when the official North Atlantic hurricane list was the Military Alphabet (Able, Baker, Charley etc., which resulted in the naming committee resorting or switching to female names exclusively from 1953 until 1979). This committee realized that if more than one Able would form in the future, what would happen in the future record books if Alpha of 2005 created so much devastation that it required Alpha to be retired? As a result, they decided to retire ‘Tropical Storm Alpha of 2005 ( which caused great devastation in Hispaniola and the loss of 26 lives) so that the name “Alpha” and other Greek names (the complete Greek Alphabet) may be used in the future should the Greek Alphabet need to be used again. The “official” term for this current tropical storm should be “Tropical Storm Zeta of 2020” and not “Tropical Storm Zeta”.
Zeta’s forecast path indicates it will not directly impact The Bahamas but an eventual landfall between Lafayette, Louisiana and Pensacola, Florida, with the center of the track in the vicinity of New Orleans. The storm’s forecast has it as a tropical storm or low-end hurricane upon landfall on Wednesday afternoon. The National Hurricane Center’s advisory stated that a slow north-northwestward to northwestward motion is expected but with a turn toward the west-northwest and an increase in forward speed forecast by Monday, followed by a faster northwestward motion on Tuesday. On the forecast track, the center of Zeta will pass south of western Cuba early Monday and move near or over the northern Yucatan Peninsula or Yucatan Channel late Monday, move into the southern Gulf of Mexico on Tuesday and reach the central Gulf of Mexico by late Tuesday. Tropical-storm-force winds extend outward up to 80 miles, mainly southeast of the center.
In the rain-battered islands of The Bahamas, over the weekend from Zeta, the double combination blow of the recent king tides and heavy rainfall (especially over low-lying areas like Pinewood Gardens last week and this weekend) has already caused coastal and inland flooding woes and rough seas for boaters. Although Zeta remains hundreds of miles from The Bahamas, a moist air mass stretching northeast of the storm drenched The Bahamas on the weekend. Given the significant amount of recent rains, particularly across the low-lying areas of the northwest and central Bahamas, these respective islands do not need much in the way of rain to experience flooding. Meanwhile, over the island of New Providence, a range from 2.5 to five inches of rainfall was the forecast for this weekend, prompting the Bahamas Department of Meteorology to issue several severe weather warnings for these islands impacted by this system.
Although both 2005 and 2020 had 27 named storms, a 2005 season reanalysis revealed a 28th system briefly became a subtropical storm far in the Atlantic on October 4, 2005. That system was never named, but because of it, 2005 technically still holds the title of busiest hurricane season on record — for now. Even with five weeks to go, the 2020 North Atlantic hurricane season, a La Niña year that spawned three major hurricanes — Laura, Teddy and Delta — has been memorable for many reasons:
• A record 24 storms were the earliest of previous seasons to be given their names.
• Hurricane Delta became the strongest storm ever named after a letter in the Greek alphabet. It became the fastest storm on record to intensify from a tropical depression to a Category 4 hurricane.
• Tropical storms Arthur and Bertha formed before the June 1 start of hurricane season, marking only the second time in recorded history two storms had formed before the season began.
• September was especially noteworthy, producing 10 named storms — a record for that month. The previous record for September was eight named storms in 2002, 2007 and 2010.
• Other records also exist; in October, a record-tying three named storms formed in a six-hour span – Tropical Storm Wilfred (Eastern Atlantic), Subtropical Storm Alpha (near Portugal) and Tropical Storm Beta (Gulf of Mexico). The only other day to have three storms form was more than 100 years ago, on August 15, 1893, according to Phil Klotzbach, hurricane researcher from Colorado State University. October also has been active with four named storms. The last time there were four or more named storms in October was 2005, when that month had six named storms, as well as that unnamed subtropical storm.
The 2020 hurricane season was predicted to be above normal by the National Oceanic and Atmospheric Administration (NOAA) in May, but was updated in August to extremely active. Colorado State’s Tropical Meteorology Project team issued its first forecast for the 2020 North Atlantic hurricane season on April 2. They forecast 16 named storms, eight hurricanes and four major hurricanes, an above-average season, but further updated their totals in subsequent season outlooks. The latest being a total of 24 named storms, 12 hurricanes and five major hurricanes on August 5. An average season, measured by standards established between 1981 and 2010, has 12 named storms, six hurricanes and three major hurricanes, defined as a Category 3 or higher on the Saffir-Simpson Hurricane Wind Scale.
The North Atlantic hurricane season outlook is based on several factors, including North Atlantic Ocean sea surface temperatures, La Niña and other teleconnections, computer model forecast guidance and past hurricane seasons exhibiting similar atmospheric conditions. However, the reasoning for this year’s bumper crop of hurricanes was because of five factors:
1. Weak to no El Niño but a strong La Niña weather pattern over the North Atlantic region;
2. Warmer-than-average sea surface temperatures (SST) in the hurricane formation zones of the North Atlantic;
3. Reduced vertical wind shear;
4. Weaker Atlantic trade winds; and
5. Enhanced West African monsoons.
However, the two most significant factors included a strong La Niña weather pattern over the North Atlantic and high SST in the tropical North Atlantic Ocean. First, warm moist air evaporating from the ocean in a process known as latent heat of condensation acts as fuel for hurricanes, pumping moisture-rich water vapor into the atmosphere that then gets carried higher by converging winds until it rains out, releasing more heat and driving the cycle forward. The North Atlantic SST so far was one of the warmest since 1993. For example, in early July, parts of the North Atlantic basin (which includes the Gulf of Mexico and
Caribbean) hit temperatures of 30 degrees Celsius (86 degrees Fahrenheit). SST in the Atlantic Ocean has been abnormally warm so far in 2020, helping fuel storms. Ocean waters typically need to be at or above 26.5 degrees Celsius (80 degrees Fahrenheit) for storms to develop, grow and thrive. In early July, parts of the North Atlantic basin (which includes North and Central America, The Bahamas, the Gulf of Mexico and the Caribbean) hit temperatures of 30 degrees Celsius (86 degrees Fahrenheit). This might not seem like much to us, but for a hurricane this is rocket fuel for its internal strengthening mechanisms within the storm, providing for rapid intensification.
Most scientists, including NOAA scientists and researcher Klotzbach, suggested that a La Niña weather pattern developed by late summer played a significant role in the increased hurricane activity. La Niña, the flip side of El Niño, is a cyclical phenomenon that brings cooler waters to the tropical Pacific Ocean and changes wind patterns over the North Atlantic in ways that can help stimulate and strengthen hurricanes. If a La Niña does develop, then the trade winds are weaker and the vertical shear is weaker, making the strong upper-level winds (jet stream) remain farther north, enhancing hurricane activity. This process allows for more thunderstorms to grow and thrive in an atmosphere more conducive to hurricanes’ development. During an El Niño year, the upper-level winds are farther south and shear off any thunderstorms tops or inhibit tropical systems development.
While The Bahamas has escaped virtually unscathed in 2020 so far, besides Hurricane Isaias in September, I must remind Bahamians that this season is still not over, so don’t let your guard down just yet because it pays to be vigilant.