Tropical Storm Gamma Moving Across The Yucatán Peninsula, Mexico

Surface observations and satellite images indicate that the center of Tropical Storm Gamma made landfall in the northeast Yucatan Peninsula near Tulum, Mexico, around 11:45 AM CDT (12:45 PM AST). The storm was very close to hurricane strength at landfall, with maximum sustained winds near 70 MPH (110 KM/H) with higher gusts.

A weather station at Xel-Ha Park, along the Yucatan coast just north of Tulum, reported a sustained wind of 55 mph (89 KM/H) and a gust to 68 mph (109 KM/H) within the past hour.

Gamma quickly strengthened from a tropical depression (Tropical Depression Twenty-Five) on Friday to a high-end tropical storm on Saturday.

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.

At 5:00 PM AST, the center of Tropical Storm Gamma was located near latitude 20.7 North, longitude 87.7 West. Gamma is moving toward the northwest near 8 MPH (13 KM/H), and a turn toward the north-northwest with decreasing forward speed is expected tonight and Sunday, followed by a turn to the west or west-southwest Sunday night or Monday. On the forecast track, the center of Gamma will continue to move over the northeastern Yucatan Peninsula through tonight, move into the southern Gulf of Mexico on Sunday, and pass near or north of the northern coast of the Yucatan Peninsula Sunday night and Monday.

Maximum sustained winds have decreased to near 65 MPH (100 KM/H) with higher gusts. Additional weakening is forecast tonight and Sunday, followed by some re-intensification by Monday.

Tropical-storm-force winds extend outward up to 80 miles (130 km) from the center. The estimated minimum central pressure is 985 millibars.

Tropical Storm Gamma Forecast Track as of 5:00 PM AST Saturday 3rd October 2020. (National Hurricane Center)
Tropical Storm Gamma Forecast Track as of 5:00 PM AST Saturday 3rd October 2020. (National Hurricane Center)

Watches & Warnings

Tropical Storm Gamma Watches and Warnings as of 5:00 PM Saturday 3rd October 2020. (National Hurricane Center)
Tropical Storm Gamma Watches and Warnings as of 5:00 PM Saturday 3rd October 2020. (National Hurricane Center)

A Tropical Storm Warning is in effect for:

  • North and west of Punta Allen to Dzilam, Mexico, including Cozumel

A Tropical Storm Watch is in effect for:

  • West of Dzilam to Progreso Mexico

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area.

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

Hazards Affecting Land

Tropical Storm Gamma probabilities for tropical-storm-force winds as of 5:00 PM AST Saturday 3rd October 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)

RAINFALL: Gamma is expected to produce rainfall of 4 to 8 inches across portions of the Yucatan Peninsula and far western Cuba, with maximum rainfall amounts as high as 10 to 15 inches possible across northeastern Quintana Roo and northern Yucatan. This rainfall may produce life-threatening flash floods.

A separate area of significant rain is possible in the Mexican states of Campeche, Tabasco, northern Chiapas, and southeast Veracruz, with rainfall of 6 to 8 inches and isolated maximum amounts of 12 inches. This rainfall may produce life-threatening flash floods and mudslides. The storm will also result in an area of heavy rains to the south that will affect the Gulf of Fonseca region between eastern El Salvador, southern Honduras, and northwest Nicaragua with accumulations of 4 to 6 inches and isolated maximum amounts of 8 inches.

Rainfall of 1 to 3 inches with maximum amounts of 5 inches is expected over the Cayman Islands.

WIND: Tropical storm conditions should continue within the Tropical Storm Warning area on the east coast of the Yucatan Peninsula for the next several hours, and these conditions should spread across the remainder of the warning area through Sunday. Tropical Storm conditions are possible within the Tropical Storm Watch area on Monday.

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

Tropical Storm Gamma Forecast Discussion

Tropical Storm Gamma moving over the Yucatan Peninsula of Mexico on Saturday afternoon (Weathernerds.org)
Tropical Storm Gamma moving over the Yucatan Peninsula of Mexico on Saturday afternoon (Weathernerds.org)

Surface observations from the Yucatan Peninsula along with high-resolution visible satellite imagery indicated that the center of Gamma made landfall in the vicinity of Tulum, Mexico, shortly before 1700 UTC. Earlier aircraft observations and pressure measurements from Tulum showed that the system was very near hurricane strength when it made landfall. A ragged eye appeared in the visible images shortly after the center crossed the coast, but that feature has since become obscured. Since Gamma has likely been slowly weakening while moving over land, the current intensity has been set to 55 kt. Continued gradual weakening is likely into Sunday while the center either moves over land or interacts with nearby land. Some re-strengthening is expected to begin by Monday, but the numerical guidance is not very enthusiastic about intensification over the Gulf, probably due to the combination of drier air and the interaction with another low-pressure system to the east. The official intensity forecast is not much different from the model consensus.

Gamma has been moving northwestward, but it is expected to turn north-northwestward while moving near and into a weakness in the subtropical ridge over the next day or so. The global models predict that a trough to the north of the tropical cyclone will lift northeastward and bypass Gamma. In a couple of days, a ridge is forecast to build back, albeit weakly, across the Gulf of Mexico. This is expected to cause the system to turn westward to southwestward over the latter part of the forecast period. The more reliable global models show the system meandering over the southern Bay of Campeche in 4 to 5 days, and so does the official forecast.

KEY MESSAGES:

  1. Gamma is expected to produce heavy rainfall for several days over portions of southeastern Mexico, the Yucatan Peninsula, Central America, and far western Cuba. This rainfall could result in life-threatening flash flooding and mudslides, particularly in the mountainous regions of southeastern Mexico and Central America.
  2. Even though Gamma has moved inland, tropical storm conditions will continue along the east coast of the Yucatan Peninsula through this evening and are expected to spread along the north coast within the Tropical Storm Warning area tonight and on Sunday.

Forecast discussion by NHC Forecaster Pasch.

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