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Tropical Storm Gamma Forecast Discussion Number 6
2020-10-03 22:38:08| National Hurricane Center (Atlantic)
Issued at 400 PM CDT Sat Oct 03 2020 000 WTNT45 KNHC 032037 TCDAT5 Tropical Storm Gamma Discussion Number 6 NWS National Hurricane Center Miami FL AL252020 400 PM CDT Sat Oct 03 2020 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 POSITIONS AND MAX WINDS INIT 03/2100Z 20.7N 87.7W 55 KT 65 MPH...INLAND 12H 04/0600Z 21.3N 88.0W 45 KT 50 MPH...INLAND 24H 04/1800Z 22.0N 88.2W 40 KT 45 MPH...OVER WATER 36H 05/0600Z 22.1N 88.4W 40 KT 45 MPH 48H 05/1800Z 22.0N 89.1W 45 KT 50 MPH 60H 06/0600Z 21.6N 90.4W 50 KT 60 MPH 72H 06/1800Z 21.0N 91.5W 50 KT 60 MPH 96H 07/1800Z 20.0N 92.0W 45 KT 50 MPH 120H 08/1800Z 20.0N 93.0W 40 KT 45 MPH $$ Forecaster Pasch
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