Tropical Depression Fourteen Heads to the Gulf of Mexico

Tropical Depression Fourteen (previously INVEST 97L) has changed little in the Western Caribbean Sea. It is forecast to become a tropical storm by Saturday

If this system gets named, it would be Marco. The current record for the earliest “M” Atlantic named storm is Maria on September 2nd, 2005.

This tropical cyclone is no threat to Trinidad, Tobago, and the Eastern Caribbean.

At 5:00 PM AST, the center of Tropical Depression Fourteen was located near latitude 17.7 North, longitude 84.3 West. The depression is moving toward the northwest near 13 MPH (20 KM/H). A slower northwestward motion is expected over the next couple of days, followed by an increase in speed by Sunday and Monday. On the forecast track, the center of the system will approach the east coast of the Yucatan Peninsula of Mexico on Saturday. The center will then cross the northeastern part of the Yucatan Peninsula Saturday night and move over the central Gulf of Mexico toward the northwestern Gulf on Sunday and Monday.

Maximum sustained winds are near 35 MPH (55 KM/H) with higher gusts. Strengthening is forecast during the next couple of days, and the depression is expected to become a tropical storm tonight. The system could be near hurricane strength when it reaches the Yucatan Peninsula of Mexico late Saturday. Additional strengthening is forecast Sunday and Monday as the system moves over the central Gulf of Mexico.

The estimated minimum central pressure is 1008 millibars.

Tropical Depression Fourteen Forecast Track as of 5:00 PM AST Friday 21st August 2020. (National Hurricane Center)
Tropical Depression Fourteen Forecast Track as of 5:00 PM AST Friday 21st August 2020. (National Hurricane Center)

Watches & Warnings

Tropical Depression Fourteen Watches and Warnings as of 5:00 PM AST Friday 21st August August 2020. (National Hurricane Center)
Tropical Depression Fourteen Watches and Warnings as of 5:00 PM AST Friday 21st August August 2020. (National Hurricane Center)

A Hurricane Watch is in effect for:

  • Punta Herrero to Cancun Mexico

A Tropical Storm Warning is in effect for:

  • Punta Herrero to Dzilam Mexico

A Hurricane Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous.

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

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

Hazards Affecting Land

Tropical Depression Fourteen probabilities for tropical-storm-force winds as of 5:00 PM AST Friday 21st August 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)
Tropical Depression Fourteen probabilities for tropical-storm-force winds as of 5:00 PM AST Friday 21st August 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)

WIND: Tropical storm conditions are expected to first reach the eastern Yucatan coast within the warning area by Saturday afternoon and will spread northward and westward within the warning area Saturday night, making outside preparations difficult or dangerous. Hurricane conditions are also possible within the hurricane watch area by late Saturday.

RAINFALL: The depression is expected to produce the following rainfall accumulations through Sunday:

  • Eastern portions of the Mexican states of Quintana Roo and Yucatan: 3 to 6 inches, isolated maximum totals of 10 inches. This rainfall may result in areas of flash flooding.
  • Eastern Honduras: 2 to 4 inches.
  • Northeast Nicaragua and the Cayman Islands: 1 to 2 inches

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

Tropical Depression Fourteen Forecast Discussion

Tropical Depression Fourteen In the Western Caribbean Sea (Weathernerds)
Tropical Depression Fourteen In the Western Caribbean Sea (Weathernerds)

Since this morning’s advisory, the low-level swirl on which the Air Force reconnaissance plane made its last fix has apparently become the new center of circulation of the depression. A little bit of deep convection has developed over this new center during the past few hours, but on the whole there is very little convective activity in the central region of the circulation. The strongest and most persistent convection is located within a band that extends across the Cayman Islands toward western Cuba. An ASCAT pass from this morning showed winds of 25-30 kt to the northeast of the new center, so 30 kt remains the initial intensity on this advisory.

It is a bit of a mystery why the depression has struggled to develop much central convection, given a seemingly low-shear environment and warm waters. Since these conditions are expected to continue for the next few days, intensification is still indicated in the official forecast, although the rate of strengthening has been muted a bit while the system approaches
the Yuctan Peninsula given its current structure. After the center moves over the Gulf of Mexico, many of the models still show the cyclone reaching hurricane intensity in about 3 days, including the intensity consensus, and that possibility is still shown in the NHC forecast. By day 4, the cyclone is likely to be blasted by 30-40 kt of southwesterly shear, which would lead to weakening while it approaches the northwestern Gulf coast. The official
forecast has been reduced at that time, although it’s noteworthy to mention that it still lies above all the guidance on day 4.

Now that there is more confidence in the initial position, the new motion estimate is a little to the right from before, but still toward the northwest, or 325/11 kt. A deep-layer trough over the Gulf of Mexico is forecast to be shoved aside by the Atlantic subtropical ridge building westward over the next 2 days. Even with this pattern change, the cyclone is expected to move generally northwestward for the entire 5-day forecast period. However, there has been a notable westward bend in some of the track models,
(particularly the GFS and ECMWF) from days 3-5, which is likely due those models having a weaker cyclone steered more by the low-level ridge at that time. Since the NHC intensity forecast is mirroring this particular model trend, the track forecast has been shifted westward from the previous prediction on days 4 and 5 toward the GFS and ECMWF solutions. The track forecast is still of rather low confidence, with the spread among the model guidance being larger than normal at every forecast time period.

Key Messages:

  1. Tropical Depression Fourteen is expected to strengthen over the northwestern Caribbean Sea through Saturday, and it could still be near hurricane strength when it reaches the east coast of the Yucatan Peninsula of Mexico late Saturday. A Hurricane Watch and a Tropical Storm Warning are in effect for portions of that region.
  2. The system is expected to move into the south-central Gulf of Mexico as a tropical storm on Sunday. Although some strengthening is anticipated Sunday and Monday, weakening is forecast as the system approaches the northwestern Gulf coast on Tuesday. It is still too soon to know exactly the location and magnitude of impacts the system will produce along the central or northwestern Gulf Coast, and interests in that area should continue monitoring the progress of this system over the next few days.

Forecast Discussion by Forecaster Berg from the NHC.

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