Tropical Depression Eta Prompts Watches for South Florida, Keys and Northwest Bahamas

Expected intensification of Tropical Depression Eta prompted the issuance of Tropical Storm Watches for parts of South Florida, the Florida Keys and the Northwestern Bahamas. At 10:00 p.m. EST on Friday the center of Tropical Depression Eta was located at latitude 18.0°N and longitude 85.2°W which put it about 275 miles (445 km) west-southwest of Gran Cayman Island. Eta was moving toward the northeast at 12 m.p.h. (19 km/h). The maximum sustained wind speed was 35 m.p.h. (55 km/h) and there were wind gusts to 45 m.p.h. (75 km/h). The minimum surface pressure was 1002 mb.

Tropical Storm Warnings were in effect for the Cayman Islands and the Cuban provinces of Camaguey, Ciego de Avila, Sancti Spiritus, Villa Clara, Cienfuegos and Matanzas. A Tropical Storm Watch was issued for the coast of South Florida from Jupiter Inlet to Bonita Beach. It included Lake Okeechobee. A Tropical Storm Watch was issued for the Florida Keys from Ocean Reef to the Dry Tortugas. A Tropical Storm Watch was in effect for the Cuban provinces of La Habana, Artemisa y Mayabeque, Pinar del Rio and the Isle of Youth. A Tropical Storm Watch was issued for the Northwestern Bahamas including the Abacos, Andros Island, the Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence.

The structure of the circulation around Tropical Depression Eta exhibited a little more organization on satellite imagery on Friday evening. More thunderstorms developed near the center of Eta. There were also more thunderstorms in bands in the eastern half of the circulation. Bands in the western half of Eta contained more showers and lower clouds. Storms near the center of Eta generated upper level divergence which pumped mass away to the northeast of the depression. Removal of mass could allow the surface pressure to decrease on Saturday.

Tropical Depression Eta will move through an environment favorable for intensification on Saturday. Eta will move over water where the Sea Surface Temperature is near 29°C. It will initially be under an upper level ridge where the winds are weaker. There will be less vertical wind shear under the ridge and Eta is likely to strengthen back to a tropical storm on Saturday. A upper level low over the western Gulf of Mexico will produce southwesterly winds which will blow toward the top of Eta on Sunday. Those winds will cause more vertical wind shear, which could limit further intensification of Eta. Eta is also likely to weaken when it crosses Cuba on Sunday. The Sea Surface Temperature of the water north of Cuba is near 29°C. So, Eta is likely to strengthen after it crosses Cuba. Eta could strengthen to a hurricane when it approaches South Florida. The wind shear caused by the upper low could eventually cause Eta to develop a structure more like a subtropical cyclone.

The upper low over the western Gulf of Mexico will be the primary feature steering Eta. Counterclockwise rotation around the cutoff low will pull Eta more toward the northeast on Saturday. Eta could pass near the Cayman Islands on Saturday. Eta is likely to move across Cuba on Sunday morning and it could drop heavy rain when it does so. The upper low will steer Eta toward the northwest on Sunday. Eta will approach South Florida and the Florida Keys on Sunday night. It could bring gusty winds and locally heavy rain to the Keys and South Florida. A high pressure system over the Atlantic Ocean will interact with the circulation around the northern side of Eta to produce strong easterly winds which will blow toward the coast of Southeast Florida. Those winds will push water toward the coast and the water level will rise several feet.