Tropical Depression Gamma Forecast To Dissipate This Week

Tropical Storm Gamma has now weakened into Tropical Depression Gamma in the far southern Gulf of Mexico. This tropical depression will bring heavy rainfall and gusty winds to parts of the Yucatán Peninsula of Mexico.

This is the 25th tropical cyclone of the 2020 Atlantic Hurricane Season and the earliest 24th named storm in Atlantic history. The previous record for the 24th named storm was Beta, on October 27th, 2005. The last (and only) time Gamma was used in the Atlantic was on November 15th, 2005.

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

At 5:00 PM AST, the center of Tropical Depression Gamma was located near latitude 22.1 North, longitude 88.1 West. The depression is moving toward the southwest near 5 mph (7 km/h), and a southwest or west-southwest motion is expected to continue through Wednesday morning. On the forecast track, the center of the depression should move inland over the northwest coast of the Yucatan peninsula Tuesday and remain over the northern portion of the peninsula and dissipate Wednesday.

Maximum sustained winds have decreased near 35 mph (55 km/h) with higher gusts. Gradual weakening is forecast, and Gamma is expected to degenerate to a post-tropical remnant low tonight and dissipate over the northern portion of the Yucatan peninsula Wednesday.

The estimated minimum central pressure is 1005 millibars.

Tropical Depression Gamma Forecast Track as of 5:00 PM AST Monday 5th October 2020. (National Hurricane Center)
Tropical Depression Gamma Forecast Track as of 5:00 PM AST Monday 5th October 2020. (National Hurricane Center)

Watches & Warnings

Tropical Depression Gamma Watches and Warnings as of 5:00 PM Monday 5th October 2020. (National Hurricane Center)
Tropical Depression Gamma Watches and Warnings as of 5:00 PM Monday 5th October 2020. (National Hurricane Center)

The government of Mexico has discontinued the Tropical Warning and the Tropical Storm Watch along the northern coast of the Yucatan peninsula.

There are no coastal watches or warnings in effect.

Hazards Affecting Land

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

RAINFALL: Through midweek, Gamma is expected to produce an additional 2 to 4 inches of rainfall with isolated maximum amounts of 8 inches across portions of the Mexican states of Yucatan, Campeche, and Tabasco. This rainfall may produce areas of flash flooding.

WIND: Gusty winds are likely along portions of the northern coast of the Yucatan Peninsula later today through Tuesday.

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

Tropical Depression Gamma Forecast Discussion

Tropical Storm Depression in the Gulf of Mexico (Weathernerds.org)

The last couple of legs of the Air Force Reserve reconnaissance aircraft mission and recent METOP-A and C scatterometer passes support lowering Gamma’s initial intensity to 30 kt for this advisory. Conventional satellite imagery reveals that the cyclone has been devoid of deep convection for nearly 10 hours and is on its way to becoming a post-tropical remnant low. Strong southerly shear and a stable, relatively dry surrounding air mass should prevent any significant convective regeneration as the system approaches the northern coast of the northwestern Yucatan peninsula tomorrow. After the remnants of Gamma makes landfall, dissipation is likely to occur Wednesday as larger, Tropical Storm Delta approaches the Yucatan Channel.

The initial motion is estimated to be southwestward, or 230/4 kt. A continued southwestward or west-southwestward motion is expected through Wednesday morning while moving inland over the northern Mexican State of Yucatan. The NHC forecast track is basically an update of this morning’s package and is based on the various multi-model consensus aids.

KEY MESSAGES:

  1. Gamma is expected to produce areas of heavy rainfall through midweek over portions of southeast Mexico, including the Mexican states of Yucatan, Campeche, and Tabasco. This rainfall could result in areas of flash flooding.
  2. Gusty winds are likely along portions of the northern coast of the Yucatan Peninsula later today through Tuesday.

Forecast discussion by NHC Forecaster Roberts.

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