BIRDSEYE VIEW POSTS

Since 2012 on the now retired Weather Underground blogs, I have been posting annotated "birdseye view" charts of the Atlantic basin, with a detailed explanation and forecasting that references the chart. From there you may know me as "NCHurricane2009." While I now do these "birdseye view" posts here, I will continue to do comments at Yale Climate Connections via Disqus where the former Weather Underground community has moved to. Feel free to reply to me there, at my Disqus feed at this link, or via e-mail at IOHurricanes@outlook.com 

 
 
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MY 2020 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #197

*******Note that forecasts and outlooks in this post are NOT the official forecast from the National Hurricane Center (NHC). They are my own detailed views on the Atlantic tropics based on current observations and latest computer model runs. As such do not make decisions based on my posts...consult news media...watches and warnings from your local weather office...and any evacuation orders issued by local governments to make the most informed and best decisions. Visit the NHC website hurricanes.gov (hurricanes dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.**********


...THURSDAY DECEMBER 3 2020 9:05 PM EDT...

A cut-off upper vortex persisting over the open central Atlantic over the last few days previously produced a subtropical surface low with its eastern divergence zone that is now being absorbed into the cold front of the frontal cyclone currently over southeastern Canada. The divergence zone of this upper vortex is now producing another thunderstorm mass in the vicinity of 20N-45W...but subtropical cyclone formation is not expected as this vortex over the next 24 hours will open to a trough while merging with the remnant upper trough to the northeast associated with the former deep-layered northeast Atlantic low pressure system. However the south part of the upper trough tied to the eastern Canada frontal cyclone is forecast to become cut-off into a second open central Atlantic upper vortex by yet another deep-layered ridge to form in the warm sector of another frontal cyclone to form along or near the US east coast. So far none of the models forecast this second upper vortex to produce a subtropical low or cyclone...therefore this is my last regularly scheduled post of the 2020 Atlantic Hurricane Season as the season officially ended on November 30. Will resume regularly scheduled posts at the start of the next hurricane season in June 2021...or unless the threat of subtropical or tropical cyclone formation returns to the Atlantic before then.

For those that may not know...the 2020 Atlantic Hurricane Season was record shattering and unprecedentedly active for modern history. It surpassed the hyperactive 2005 season in many ways...I never thought I would witness such activity again in my lifetime until the 2020 season proved me wrong. Here is a list of many of the records broken by the 2020 Atlantic Hurricane Season:

*The formation of Tropical Storm

Arthur on May 16 marks the sixth Atlantic Hurricane Season in a row (2015-2020) where the first named storm formed before the traditional June 1st start.

*Earliest third named storm on record...Cristobal formed on June 1st...beating Colin of 2015 (Colin formed June 5th that year).

*Earliest fifth named storm on record...Edouard formed on July 6...beating Emily of 2005 (Emily formed July 11th that year).

*From July to September...all subsequent Atlantic (sub)tropical cyclones that formed this year set records for the earliest formation dates on record...from Fay which was the earliest sixth named storm on record...to Wilfred which was the earliest twenty-first named storm on record (https://en.m.wikipedia.org/wiki/List_of_Atlantic_hurricane_records#Earliest_/_latest_formations_for_each_category ). Many of these records were previously set in the 2005 Atlantic Hurricane Season.

*Earliest use of the Greek Alphabet list of names...when Subtropical Storm Alpha formed on September 18 it beat Tropical Storm Alpha of 2005 which formed on October 22 that year.

*First time on record Greek Alphabet named storms strike the United States...Beta...Delta... Zeta along the US Gulf coast... Eta on the west Florida peninsula coast.

*Most number of tropical cyclone landfalls in the United States in a single season which totaled 12 as follows:

May 27...Bertha...South Carolina...Storm

June 7...Cristobal...SE Louisiana...Storm

July 10...Fay...NE New Jersey...Storm

July 25...Hanna...S Texas...Cat 1 Hurricane

August 4...Isaias...North Carolina...Cat 1 Hurr.

August 24...Marco...SE Louisiana...Storm

August 27...Laura...SW Louisiana...Cat 4 Hurr.

September 15...Sally...Alabama...Cat 2 Hurr.

September 22...Beta...Texas...Storm

October 9...Delta...SW Louisiana...Cat 2 Hurr.

October 27...Zeta...SE Louisiana...Cat 2 Hurr.

November 12...Eta...NW Florida...Storm

*Most number of storms to strike Louisiana in a single season...five...see above list (www.washingtonpost.com/weather/2020/11/10/record-hurricane-season-atlantic/%3foutputType=amp)

*2020 ties with 1985 and 1886 for the most number of US hurricane landfalls...six... see above list (https://www.google.com/amp/s/amp.usatoday.com/amp/6070143002)

*Concerning rapid intensification...2020 is the only Atlantic season where 2 storms had a 105 mph max sustained wind increase in the matter of only 36 hours...Delta and Eta. Only four other Atlantic storms achieved such an intensification feat to our knowledge...Felix 2007...Wilma 2005...Andrew 1992...and the Florida Keys Labor Day Hurricane of 1935 (www.washingtonpost.com/weather/2020/11/10/record-hurricane-season-atlantic/%3foutputType=amp)

*Most number of Greek named storms in an Atlantic season...nine (Alpha... Beta... Gamma... Delta... Epsilon... Zeta... Eta.. Theta... Iota). And to think there are entire Altantic seasons where only nine storms form! Previous record was set in 2005 with six Greek named storms. This is only the second Atlantic season to reach the Greek Alphabet.

*Most number of Atlantic tropical and subtropical cyclones of at least 40+ mph maximum sustained wind storm strength..30. The previous record set in 2005 was 28.

*Most number of November Atlantic major (Category 3+) hurricanes...two...which were Eta and Iota.


*Shortest time between two major hurricane strikes in Nicaragua...only two weeks. Eta made landfall as a category 4 on November 3...Iota made landfall as a category 4 on November 17. The landfall location of both hurricanes were only 15 miles apart.


*Iota is only the second Atlantic November category 5 hurricane on record...with the 1932 Cuba hurricane being the other. The 1932 hurricane reached category 5 in the first week of November...making Iota the latest occurring category 5 in the Atlantic on record.


*In 1932 there was an additional and weaker Atlantic hurricane after the category 5 Cuba hurricane. This means if nothing forms between now and December 31st...this will be the first Atlantic hurricane season whose last storm was a category 5.


*Iota broke the record for the lowest landfall central pressure of any Nicaragua landfall while at 920 mb...beating Joan of 1988 which made landfall at 932 mb.


*With Iota...this marks five Atlantic hurricane seasons in a row with a category 5 hurricane (Dorian 2019...Michael 2018...Irma 2017...Maria 2017...Matthew 2016)


...COMPUTER MODEL SUMMARY...

Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)


1200Z CMC Model Run...No tropical cyclone formation in the Atlantic basin over the next 168 hours (7 days)

1200Z ECMWF Model Run...No tropical cyclone formation in the Atlantic basin over the next 168 hours (7 days)


1200Z GFS Model Run...No tropical cyclone formation in the Atlantic basin over the next 168 hours (7 days)


1200Z NAVGEM Model Run...No tropical cyclone formation in the Atlantic basin over the next 168 hours (7 days)


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