Tropical Storm Gamma Stationery In The Gulf of Mexico

Tropical Storm Gamma is now in the Gulf of Mexico, forecast to slowly move to the southwest over the next week. This tropical storm will bring heavy rainfall and gusty winds to parts 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.

At 5:00 PM AST, the center of Tropical Storm Gamma was located near latitude 22.4 North, longitude 87.8 West and has stalled just north of the northern coast of the Yucatan Peninsula. Gamma should slowly turn toward the west-southwest tonight or Monday, and a west-southwestward drift should continue Monday night through early Wednesday. On the forecast track, the center of Gamma will meander offshore of the northern Yucatan Peninsula and over the extreme southern Gulf of Mexico today, and pass near or just offshore of the northern coast of the Yucatan Peninsula on Monday and Tuesday.

Maximum sustained winds are near 60 mph (95 km/h) with higher gusts. Gradual weakening is anticipated to begin later tonight or on Monday and continue into Tuesday. Afterward, little change in strength is forecast.

Tropical-storm-force winds extend outward up to 160 miles (260 km) from the center. The estimated minimum central pressure is 997 millibars.

Tropical Storm Gamma Forecast Track as of 5:00 PM AST Sunday 4th  October 2020. (National Hurricane Center)
Tropical Storm Gamma Forecast Track as of 5:00 PM AST Sunday 4th October 2020. (National Hurricane Center)

Watches & Warnings

Tropical Storm Gamma Watches and Warnings as of 5:00 PM Sunday 4th October 2020. (National Hurricane Center)
Tropical Storm Gamma Watches and Warnings as of 5:00 PM Sunday 4th October 2020. (National Hurricane Center)

A Tropical Storm Warning is in effect for:

  • North and west of Cancun to Dzilam Mexico

A Tropical Storm Watch is in effect for:

  • West of Dzilam to Progreso Mexico

A Tropical Storm Warning means that tropical storm conditions are occurring 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 Sunday 4th October 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)
Tropical Storm Gamma probabilities for tropical-storm-force winds as of 5:00 PM AST Sunday 4th 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 an additional 3 to 6 inches of rainfall, with isolated maximum amounts of 8 inches, across portions of the Mexican states of Yucatan, Campeche and Tabasco. This rainfall may enhance any ongoing flash flooding and result in new areas of flash flooding into the middle of the week.

WIND: Tropical storm conditions should continue within portions of the Tropical Storm Warning area on northern coast of the Yucatan through today. Tropical Storm conditions are possible within the Tropical Storm Watch area later today through Monday.

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

Tropical Storm Gamma Forecast Discussion

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

The last aircraft reconnaissance fix, recorded a couple of hours ago, indicated that Gamma’s center had wobbled a little to the right of the previous 6-hour motion and is located near the southeastern edge of the convective canopy. Flight-level winds adjusted to the surface, SFMR wind data, and a blend of Dvorak satellite intensity estimate from TAFB and SAB still support an initial intensity of 50 kt for this advisory.

The UW-CIMSS shear analysis reveals stiff 20-25 kt southerly shear impinging on the south portion of the cyclone. Subsequently, the large-scale models and the ECMWF/GFS statistical-dynamical intensity guidance show the shear magnitude increasing during the next 24 hours. This inhibiting upper wind pattern should induce weakening soon. Although the shear is predicted to decrease somewhat around mid-period, Gamma should exhibit little change in strength through the remaining period which is in best agreement with all of the skilled intensity guidance. As mentioned in previous advisories, it cannot be stressed enough the relatively high level of uncertainty in this intensity forecast, and that it’s primarily dependent on whether or not the cyclone moves back over the Yucatan Peninsula.

Gamma should continue to move little, or meander over the southern Gulf of Mexico, near the northern coast of the Yucatan Peninsula through most of tomorrow. By Monday night, the global models are in good agreement with the western extent of a subtropical ridge reestablishing temporarily over the central Gulf of Mexico. This change in the synoptic steering pattern should cause the cyclone to turn and move west-southwestward through the 72 hour forecast period. After a brief reduction in forward speed late Wednesday, while Potential-Tropical Cyclone Twenty-Six moves into the central Gulf of Mexico, a turn toward the northwest is expected on Thursday as the ridge, once again, builds back over the central Gulf in response to PTC Twenty-Six approaching the northern Gulf coast. The official track forecast is adjusted to the left of the previous one through the 60 hour period to agree more with the HCCA consensus and shifted to the right through day 5.

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 is just offshore, tropical storm conditions will continue across portions of the northern coast of the Yucatan Peninsula today.

Forecast discussion by NHC Forecaster Pasch.

Facebook Comments