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.


15 November 2020

Hurricane Iota threatens recently-devastated Nicaragua

Since my previous update on Wednesday, the tropical wave in the Caribbean was upgraded to Tropical Depression 31 on Friday morning, then again to Tropical Storm Iota on Friday afternoon, making it the season's 30th named storm. On Sunday morning, it was upgraded to Hurricane Iota, the season's 13th hurricane.  The only other known season with 13 hurricanes was 2005 -- it ended up with 15.


Iota is tracking toward the west, which will bring it to northern Nicaragua in a couple days. You may recall that Eta just made landfall in this same part of Nicaragua on November 3 as a Category 4 hurricane; another Category 4-5 landfall only two weeks later is just unthinkable, but that appears to be exactly the situation. The wind, the flooding rain, the storm surge... all coming back to the same places in Central America. Unlike Eta, there is no indication that Iota will turn north out of Guatemala and head back over the western Caribbean.


Also, Eta made landfall in the Big Bend area of Florida on Thursday as a tropical storm, and Tropical Depression Theta is hours away from dissipating as a low-level swirl north of the Canary Islands. There are no other features of interest on the map right now, but when the time comes (and I'm sure it will), the next name on the list is Kappa.


To call the 2020 track map crowded would be an understatement. It's literally two seasons crammed into one, and it's not over yet.  While the official season spans June 1 through November 30, these hyper-active seasons tend to ooze out of those artificial start and end bounds.

11 November 2020

Eta a hurricane again, Theta forms, Iota on the horizon

No, it's not September 11, it's November 11 and we are watching a hurricane in the Gulf of Mexico, a tropical storm out by the Azores, and a potent tropical wave in the Caribbean.  This is not normal.

First, after a stall by the western tip of Cuba, Eta began moving north and has regained hurricane intensity just west of Fort Myers, FL.  It is forecast to start a turn toward the northeast which will bring in to landfall north of Tampa, FL on Thursday.  Although it's been ingesting huge amounts of dry air into its circulation from the west, the low wind shear and warm water below it are enough to not just keep it going, but to allow it to intensify!


As such, hurricane watches are in effect for a portion of western Florida, along with storm surge warnings (check https://www.nhc.noaa.gov/graphics_at4.shtml?start#contents for the latest). Tampa Bay could see at least a 3-5-foot storm surge from this when it makes landfall on Thursday and the area could see up to a half foot of rain. If we rewind back to the beginning, the storm that is now Eta left the African coast as a tropical wave back on October 24th!! What a long strange trip it's been.


The strong low pressure system that was located southwest of the Azores was upgraded to Subtropical Storm Theta on Monday night, making it the season's record-breaking 29th named storm. It has since transitioned to a tropical cyclone and is forecast to slide between the Azores and the Canary Islands this weekend as a tropical storm.


And the wave in the Caribbean is still a feature of great interest -- NHC is giving it an 80% probability of developing into a tropical cyclone by the end of the weekend. This is quite unusual to be watching a vigorous tropical wave in the Caribbean in NOVEMBER. Unfortunately, it's on a trajectory that would take it near where Category 4 Hurricane Eta just made landfall a week ago.


If this does in fact develop and become a tropical storm, it would be named Iota and would be the season's 30th named storm.  If it becomes a hurricane, it would be the season's 13th hurricane. Only one other season in known history had 13+ hurricanes, and that was 2005 (it had 15).