Tropical Storm Iota formed in the central Caribbean Friday afternoon, becoming the 30th named storm of this record-busy 2020 Atlantic hurricane season. The previous record for most named storms in a season was 28, set in 2005.
Iota is predicted to rapidly intensify and be close to major hurricane strength on Monday night, when it will be approaching landfall near the Nicaragua/Honduras border. Iota will likely bring catastrophic rains of 8-16 inches, with isolated amounts of 20-30 inches, to portions of Central America still recovering from devastating Hurricane Eta, which hit northern Nicaragua as a category 4 storm with 140 mph winds on November 3.
At 1 p.m. EST Saturday, Iota was 375 miles south of Kingston, Jamaica, headed west-southwest at 5 mph. Iota had top winds of 50 mph, with a central pressure of 1002 mb. Satellite imagery showed Iota’s heavy thunderstorms mostly confined to the south and east sides of the center of circulation, but they were steadily becoming more organized, and were beginning to move over the center of circulation. Upper-level winds out of the northwest were creating about 10 knots of wind shear, restricting heavy thunderstorm activity on Iota’s northwest side.
The first Hurricane Hunter mission into Iota is scheduled for Saturday afternoon.
Record late-season activity
Iota’s formation in November gives the 2020 Atlantic hurricane two records for late-season activity: five Caribbean named storms since October 1 (tying with 2005 for most Caribbean named storm formations after October 1), and three November named storms (tying with 1931, 1961, 2001 and 2005 for most Atlantic named storms to form in November). As measured by accumulated cyclone energy (ACE), Atlantic hurricane activity since October 20 has been more akin to what is seen in an average September – typically the peak month of hurricane season. (Thanks go to Dr. Phil Klotzbach for these stats.)
Track forecast for Iota
A ridge of high pressure to Iota’s northwest will slide to the east on Saturday afternoon, resulting in a more westerly to west-northwesterly motion of Iota until landfall occurs near the Nicaragua/Honduras border on Monday night.
As a result of a relocation of Iota’s center to the south on Saturday morning, which put the center near the most intense thunderstorms, a more southerly path for the storm is now predicted. This shift should help Iota avoid a worst-case scenario for Honduras: Had the storm moved parallel to and just offshore of the coast, it could maintain its strength longer, subjecting the region to much higher rainfall totals. This scenario is looking much less likely than it did 24 hours ago, with only the 6Z Saturday run of the HWRF model and a few of the members of the GFS ensemble predicting it.
Once Iota makes landfall, steering currents are predicted to shift, putting Iota on a more west-southwesterly path deep into Central America. Dissipation is expected to occur about two days after landfall, when Iota will be close to emerging into the Pacific Ocean near the El Salvador coast. There continues to be almost no model support for the idea that Iota might move northward into the Gulf of Mexico and threaten the U.S., as so many other storms this year have done.
Intensity forecast for Iota
The intensity forecast from the National Hurricane Center continues to be aggressive, calling for Iota to intensify from 40 mph to 110 mph – to the brink of category 3 status – in just 60 hours. Keep in mind, though, that NHC and the intensity models tend to under-predict rapid intensification events in the western Caribbean, and it would not be surprising for Iota to become a category 4 storm with 130 mph winds or higher at its peak.
Conditions for development will be favorable for development of Iota through landfall, with the SHIPS model predicting light wind shear less than 10 knots, warm sea surface temperatures of 29 degrees Celsius (84°F), and a moist atmosphere with a mid-level relative humidity of 70%. The 12Z Saturday SHIPS model gave a 52% chance that Iota would follow the NHC intensity forecast, and increase its winds by 75 mph in 72 hours. This probability is 10 times higher than the climatological mean.
These conditions are very similar to what Hurricane Eta experienced during its rapid intensification episode as it approached landfall in Nicaragua nearly two weeks ago. Although Iota will be passing over the same part of the Caribbean traversed by Eta, the sea surface temperature has not cooled much, remaining about 0.5°C above average.
Iota is a significant threat to intensify into a major hurricane that will affect the same areas of the Caribbean impacted by Hurricane Eta. In particular, Nicaragua and Honduras, which were devastated by flooding from Hurricane Eta’s torrential rains of over 20 inches, appear at great risk of receiving similar rains from Iota, beginning on Sunday night or Monday morning.
Typhoon Vamco approaching landfall in typhoon-weary Vietnam
Long-suffering Vietnam – which has already been affected by 10 tropical cyclones this year – is now bracing for number 11.
Typhoon Vamco surged from category 1 to category 4 strength in just 12 hours on Friday, peaking with top winds of 130 mph at 1 p.m. EST November 13, according to the Joint Typhoon Warning Center. As Vamco moved toward Vietnam Friday night and Saturday morning, the typhoon moved over cool waters of 26 degrees Celsius (79°F), weakening it to 110 mph winds at 7 a.m. EST Saturday, November 14. Vamco is expected to weaken further, to a category 1 typhoon with 80 mph winds, on Saturday night (U.S. EST), as it makes landfall over northern Vietnam.
Vamco clobbered the Philippines on Wednesday as a category 2 storm with 110 mph winds, killing at least 53 people.
Theta almost dead
Tropical Storm Theta was barely clinging to tropical storm status on Saturday morning, with 40 mph winds, as it headed east at 8 mph over the waters about 600 miles southeast of the Azores Islands. Dry air, high wind shear, and cold waters are predicted to reduce Theta to a remnant low on Saturday night.
Editor’s note: The headline on this post was revised at 6:25pm EST on November 14.
Bob Henson contributed to this post.
Posted on November 14, 2020(1:27pm EST)