Tropical Storm Iota Forms, Forecast To Become A Major Hurricane

Tropical Depression Thirty-One has strengthened into Tropical Storm Iota in the Caribbean Sea. Iota is forecast to become a dangerous and major hurricane early this upcoming week as it nears Central America. Iota will likely impact Honduras and Nicaragua, already reeling from Hurricane Eta’s recent deluge.

With the formation of Tropical Depression Thirty-One, now Tropical Storm Iota, 2020 has now recorded 31 systems that reached tropical depression strength and 30 named storms. Breaking 2005’s record, that season recorded 31 systems that reached tropical depression strength, with 28 named storms. This is the first time Iota has been used operationally in Atlantic History.

Iota is forecast to be a major blow to Nicaragua, Honduras, and Guatemala, still recovering from the devastating impact of Eta just last weekend. Rainfall totals between 20 to 30 inches are possible. This rainfall would lead to significant, life-threatening flash flooding and river flooding, along with landslides in areas of higher terrain.

This tropical cyclone is not forecast to directly impact Trinidad, Tobago, or the Lesser Antilles as it moves generally eastward.

List of names for the 2020 Atlantic Hurricane Season. The next named tropical cyclone will be called Kappa.
List of names for the 2020 Atlantic Hurricane Season. The next named tropical cyclone will be called Kappa.

At 5:00 PM AST, the center of Tropical Storm Iota was located near latitude 13.8 North, longitude 74.3 West. Iota is moving toward the west-southwest near 3 mph (6 km/h), and this motion is expected to continue through early Saturday. A westward to west-northwestward motion at a slightly faster forward speed is expected to begin by late Saturday and continue through Monday. On the forecast track, Iota will move across the central Caribbean Sea during the next day or so, and approach the coasts of Nicaragua and northeastern Honduras late Sunday and Monday.

Maximum sustained winds have increased to near 40 mph (65 km/h) with higher gusts. Steady to rapid strengthening is likely over the weekend, and the system is forecast to be a major hurricane when it approaches Central America.

Tropical-storm-force winds extend outward up to 105 miles (165 km) from the center. The estimated minimum central pressure is 1006 millibars.

Tropical Storm Iota Forecast Track as of 5:00 PM AST Friday 13th November 2020. (National Hurricane Center)
Tropical Storm Iota Forecast Track as of 5:00 PM AST Friday 13th November 2020. (National Hurricane Center)

Watches & Warnings

Tropical Storm Iota Watches and Warnings as of 5:00 PM AST Friday 13th November 2020. (National Hurricane Center)

There are no coastal watches or warning in effect.

Interests in Nicaragua and Honduras should monitor the progress of this system. A Hurricane Watch may be required for a portion of that area tonight or early Saturday.

Hazards Affecting Land

Tropical Storm Iota probabilities for tropical-storm-force winds as of 5:00 PM AST Friday 13th November 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)
Tropical Storm Iota probabilities for tropical-storm-force winds as of 5:00 PM AST Friday 13th November 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)

Rainfall: Through Wednesday morning, Iota is expected to produce 4 to 8 inches of rain, with local 12 inch totals, across portions of northern Colombia, Panama and Costa Rica.

Across Jamaica and southern Haiti, 2 to 4 inches are expected, with local amounts up to 6 inches.

Across the remaining sections of Central America, the system has the potential to produce 20 to 30 inches of rain with a focus across northern Nicaragua and Honduras. This rainfall would lead to significant, life-threatening flash flooding and river flooding, along with landslides in areas of higher terrain.

SURF: Swells generated by Iota will begin affecting portions of the coast of Colombia, and the southern coasts of Hispaniola and Jamaica during the next day or so. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.

This system is of no direct threat to the Windward Islands, including Trinidad and Tobago.

Tropical Storm Iota Forecast Discussion

Tropical Storm Iota (Weathernerds.org)

Banding features over the eastern and southeastern portions of the cyclone’s circulation have increased since this morning, and the overall organization of the system continues to quickly improve. Earlier ASCAT data indicated that there was a fairly large area of light winds near the center and that the low-level center was displaced to the northwest of the mid-level center seen in visible satellite imagery. Since the system is still in its formative stage, the low-level center may reform closer to the mid-level feature, and the advisory position is a compromise between the low- and mid-level circulations. The earlier ASCAT data indicated peak winds of around 30 kt with several higher rain-inflated vectors. Based on the continued increase in organization, and Dvorak T-numbers of T2.5 from both TAFB and SAB, the initial intensity is raised to 35 kt. Iota becomes the 30th named storm of the recording-breaking 2020 hurricane season.

The environment ahead of Iota appears to be quite conducive for intensification. The system will be moving over warm waters, in a moist atmosphere, and within an area of very low vertical wind shear. As a result, steady to rapid strengthening appears likely over the next few days. The NHC intensity forecast calls for Iota to reach hurricane status within 36 h and now calls for the system to be a major hurricane when it approaches the coast of Central America. The NHC intensity forecast is in good agreement with the HFIP corrected consensus model, and the 70-kt increase in intensity over the next 72 hours is supported by the SHIPS Rapid Intensification Index that shows a nearly 60 percent chance of a 65 kt increase in intensity during that time period.

The tropical storm has not moved very much today, and the initial motion estimate is a somewhat uncertain 255/3 kt. A strong mid-level ridge that extends across Florida and the western Atlantic is forecast to slide eastward over the next few days causing the cyclone to move faster toward the west or west-northwestward. The track guidance has come into a bit better agreement this afternoon, with only the HWRF showing a track farther north over the northwestern Caribbean Sea. The latest consensus aids were very close to the previous official forecast, and no significant adjustments to the earlier track forecast were required.

Key Messages:

  1. Iota is expected to strengthen and be a major hurricane when it approaches the coast of Central America. There is a risk of dangerous wind, storm surge, and rainfall impacts across portions of Nicaragua and Honduras beginning Sunday night or early Monday. Hurricane Watches will likely be issued for a portion of this area tonight or early Saturday.
  2. Through Wednesday morning, heavy rainfall from Iota may lead to life-threatening flash flooding and river flooding across portions of Haiti, Jamaica, and Central America. Flooding and landslides from heavy rainfall could be significant across Central America given recovery efforts underway after Hurricane Eta.

Forecast discussion by NHC Forecaster Brown.

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