Tropical Storm Zeta Forms, Forecast To Become A Hurricane

Tropical Depression Twenty-Eight strengthened into Tropical Storm Zeta early Sunday morning in the northwestern Caribbean Sea, becoming the 28th tropical cyclone and 27th named storm for 2020. This system is forecast to strengthen into a hurricane as it enters the Gulf of Mexico this week.

Zeta 2020 has become the earliest 27th named storm in Atlantic History, edging out 2005’s version of Epsilon which formed on November 29th. The last and only time Zeta was used was on December 30th, 2005.

2005 still holds the record for the most number of named storms in a season at 28. The National Hurricane Center identified an “unnamed” subtropical storm in its post-season analysis that year, which is included in the total. With Zeta, the number for 2020 currently stands at 27.

This tropical cyclone is not forecast to impact Trinidad, Tobago, or the Lesser Antilles.

List of names for the 2020 Atlantic Hurricane Season. The next named tropical cyclone will be called Eta.
List of names for the 2020 Atlantic Hurricane Season. The next named tropical cyclone will be called Eta.
List of Greek names for the Atlantic Hurricane Season. The next named tropical cyclone will be called Eta. If this name is used, it will be used for the first time in recorded history.
List of Greek names for the Atlantic Hurricane Season. The next named tropical cyclone will be called Eta. If this name is used, it will be used for the first time in recorded history.

At 5:00 PM AST, the center of Tropical Storm Zeta was located near latitude 17.7 North, longitude 83.4 West. Zeta has been meandering or nearly stationary, but a generally northwestward motion is expected over the next couple of days. On the forecast track, the center of Zeta will pass south of western Cuba early Monday and move near or over the northern Yucatan Peninsula or the Yucatan Channel late Monday, move into the southern Gulf of Mexico on Tuesday, and reach the central Gulf of Mexico by late Tuesday.

Reports from a NOAA Hurricane Hunter aircraft indicate that the maximum sustained winds have increased near 50 mph (85 km/h) with higher gusts. Strengthening is forecast during the next 48 hours, and Zeta is expected to become a hurricane before it moves near or over the Yucatan Peninsula late Monday. Tropical-storm-force winds extend outward up to 115 miles (185 km) from the center.

The minimum central pressure, estimated from NOAA Hurricane Hunter
aircraft observations, is 999 millibars.

Tropical Storm Zeta Forecast Track as of 5:00 PM AST Sunday 25th October 2020. (National Hurricane Center)
Tropical Storm Zeta Forecast Track as of 5:00 PM AST Sunday 25th October 2020. (National Hurricane Center)

Watches & Warnings

Tropical Storm Zeta Watches and Warnings as of 5:00 PM AST Sunday 25th October 2020. (National Hurricane Center)
Tropical Storm Zeta Watches and Warnings as of 5:00 PM AST Sunday 25th October 2020. (National Hurricane Center)

A Hurricane Warning is in effect for:

  • Tulum to Rio Lagartos Mexico
  • Cozumel

A Tropical Storm Warning is in effect for:

  • Pinar del Rio Cuba

A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion.

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.

For storm information specific to your area, please monitor products issued by your national meteorological service.

Hazards Affecting Land

Tropical Storm Zeta probabilities for tropical-storm-force winds as of 5:00 PM AST Sunday 25th October 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)
Tropical Storm Zeta probabilities for tropical-storm-force winds as of 5:00 PM AST Sunday 25th October 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)

RAINFALL: Rainfall totals of 4 to 8 inches with local amounts of 12 inches are possible through Wednesday along and east-northeast of Zetas track from Jamaica, the Cayman Islands, central to western Cuba, and the northeast Yucatan peninsula of Mexico. Additional rainfall amounts of 1 to 3 inches with local amounts of 5 inches possible across Southern Florida and the Keys over the next 2 days, with isolated storm totals of 8 inches.

By Wednesday, heavy rainfall associated with Zeta will begin to affect the central Gulf Coast region, which may lead to flash flooding in urban areas.

WIND: Hurricane conditions are expected within the Hurricane Warning area in the Yucatan Peninsula by late Monday. Tropical storm conditions could occur in the warning area in Western Cuba on Monday.

STORM SURGE: A dangerous storm surge will raise water levels by as much as 1-3 feet above normal tide levels along the immediate coast in the Hurricane Warning area near and to the north of where the center makes landfall in the Yucatan Peninsula.

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

Tropical Storm Zeta Forecast Discussion

Tropical Storm Zeta (Weathernerds.org)
Tropical Storm Zeta (Weathernerds.org)

Although the overall cloud pattern of Zeta is still not very well organized, with a lack of distinct banding features, it continues to generate very intense deep convection mainly over the southeastern portion of the circulation. Moreover, in spite of its ragged appearance, the storm has strengthened today. Reports from a NOAA Hurricane Hunter aircraft investigating the system this afternoon indicate that, based on adjusted flight-level and SFMR-observed surface winds, the intensity has increased to near 45 kt and the central pressure has fallen to 999 mb.

Since the storm will be moving over the high oceanic heat content of the northwestern Caribbean Sea and in a moist environment with low vertical shear through Monday, strengthening is forecast and Zeta will likely become a hurricane before it nears the Yucatan Peninsula in a day or so. After Zeta moves into the Gulf of Mexico, southwesterly shear is likely to increase and oceanic heat content below the cyclone will diminish, especially when the system approaches the northern Gulf coast on Wednesday. Therefore, no strengthening is forecast in 2-3 days and Zeta could be weakening by the time it reaches the northern Gulf coast. However, the intensity forecast is still subject to significant uncertainty.

The center has been meandering this afternoon, and apparently has reformed nearer to the deep convection over the southeastern quadrant. Since this is not considered representative of larger-scale motion, the system is still considered to be quasi-stationary at this time. However, the track guidance is in agreement that Zeta will move northwestward over the next 1-2 days, passing near or over the Yucatan Peninsula. Thereafter, the cyclone is likely to turn north-northwestward to northward while it moves on the western side of a mid-tropospheric anticyclone near Florida. A turn toward the north-northeast is expected when Zeta nears the northern Gulf coast, due to an approaching shortwave trough. The track guidance has more than the usual amount of spread at the 72-hour time frame, with the ECMWF and the GFS predictions being about 300 miles apart near the northern Gulf coast. The official forecast track lies between these 2 solutions, and is similar to the previous NHC track. However, given the inherent uncertainties, one should not focus on the exact forecast track.

Based on the new intensity forecast, the government of Mexico has issued a Hurricane Warning for a portion of the Yucatan peninsula.

KEY MESSAGES:

  1. Hurricane conditions and storm surge are expected in portions of the northern Yucatan Peninsula of Mexico Monday night and early Tuesday. Tropical storm conditions could occur over extreme western Cuba on Monday.
  2. Through Wednesday, heavy rainfall is expected from Zeta across portions of central and western Cuba, the Cayman Islands, Jamaica, the northeast Yucatan peninsula of Mexico, southern Florida, and the Keys. This rainfall may lead to flash flooding in urban areas.
  3. Zeta is forecast to be at or just below hurricane strength when it approaches the northern Gulf Coast on Wednesday, and there is an increasing risk of storm surge, rainfall, and wind impacts from Louisiana to the Florida Panhandle. Residents in these areas should monitor the progress of Zeta and updates to the forecast.

Forecast discussion by NHC Forecaster Pasch.

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