17 November 2020

Iota becomes Category 5 hurricane before landfall in Nicaragua

Enhanced satellite image of Hurricane Iota as it made landfall in Nicaragua on 17 November 0400 UTC.

From bad to worse... Category 4 Hurricane Eta made landfall in Nicaragua two weeks ago today, spreading catastrophic wind, flooding, and mudslides far inland through Central America. On Monday, Iota rapidly intensified to become the season's strongest hurricane, reaching Category 5 intensity just prior to making landfall in the same location as Eta. It "weakened" only slightly to a top-end Category 4 hurricane as the eye crossed the coastline early Tuesday morning. It's impossible to imagine two such hurricanes in two weeks at the same location. Iota will now dissipate over the mountainous terrain of Central America, dumping huge amounts of rain along the way. 

Iota was the only Category 5 hurricane of the 2020 season (so far), but it also claimed the title of being the latest Category 5 hurricane on record.  The one and only other candidate was in early November of 1932.  It also marks an unprecedented string of five consecutive years with Category 5 hurricanes in the Atlantic. This map below shows the tracks of the seven Category 5 hurricanes that have occurred over the past five years: Matthew (2016), Irma (2017), Maria (2017), Michael (2018), Dorian (2019), Lorenzo (2019), and Iota (2020).  Then there were ZERO from 2008-2015, then eight from 2003-2007. They definitely come in surges.

Unfortunately, there's a hint of another tropical wave right behind Iota, and there is some support for its development in the models -- the National Hurricane Center is giving it a 40% probability of forming later this week as it approaches Central America. This map shows a forecast of minimum surface pressures of trackable lows from the American GFS model ensemble on Friday, and that clustering of ensemble members near Costa Rica and Nicaragua is very troubling. Should this become a tropical storm, it would be the season's 31st and be named Kappa.

While the season continues to obliterate records for the number of named storms, the earliest formation date of the Nth named storm, and also for number of landfalls, it just now snuck into 10th place in terms of ACE (Accumulated Cyclone Energy).  ACE is a common metric used which basically accounts for overall intensity and duration, not the number of storms or where they go. The nine years that had more ACE are all very familiar to tropical cyclone enthusiasts: 1933, 1926, 2005, 1893, 1995, 2004, 2017, 1950, and 1961. It's fitting that 2020 now joins the top ten list.

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