Tag Archives: Marathon

Tropical Storm Eta Drops Heavy Rain on South Florida

Tropical Storm Eta dropped heavy rain on parts of South Florida on Sunday. At 10:00 p.m. EST on Sunday the center of Tropical Storm Eta was located at latitude 24.6°N and longitude 80.5°W which put it about 40 miles (65 km) east of Marathon, Florida. Eta was moving toward the northwest at 14 m.p.h. (22 km/h). The maximum sustained wind speed was 65 m.p.h. (105 km/h) and there were wind gusts to 80 m.p.h. (130 km/h). The minimum surface pressure was 993 mb.

A Hurricane Warning was in effect for the Florida Keys from Ocean Reef to the Dry Tortugas. A Hurricane Watch was in effect for the portion of the coast from Golden Beach to Bonita Beach, Florida. A Tropical Storm Warning was in effect for the portion of the coast from the Brevard/Volusia County Line to Englewood, Florida. A Tropical Storm Warning was in effect for Lake Okeechobee. A Tropical Storm Warning was in effect for the Northwestern Bahamas including the Abacos, Andros Island, the Berry Islands, Bimini, Eleuthera, Grand Bahama Island and New Providence. A Tropical Storm Watch was in effect for the portion of the coast from Englewood to Anna Maria Island, Florida. A Tropical Storm Watch was in effect for the Cuban provinces of La Habana, Artemisa, Mayabeque, Pinar del Rio and the Isle of Youth.

The circulation around Tropical Storm Eta weakened when it moved across Cuba on Sunday morning. Drier air wrapping around the southern side of an upper level low over the northwestern Caribbean Sea was pulled into the core of Tropical Storm Eta and the thunderstorms near the core weakened. Even though the inner core of Eta was weaker, the tropical storm still had a well developed low level circulation. Stronger thunderstorms were occurring in bands north and east of the center of Tropical Storm Eta. Bands south and west of the center consisted primarily of showers and lower clouds.

The asymmetric distribution of thunderstorms and the lack of thunderstorms in the core of Tropical Storm Eta was also affecting the wind pattern. Low pressure at the center of Eta and a strong high pressure system over the Atlantic Ocean generated a strong pressure gradient northeast of the center of circulation. Winds to tropical storm force extended out 300 miles (485 km) to the northeast of the center of Tropical Storm Eta. Several stations along the southeast coast of Florida were reporting winds to tropical storm force. Winds to tropical storm force extended out 150 mile (240 km) northwest and southeast of the center of Eta. Winds to tropical storm force only extended out 40 miles (65 km) in the southwestern quadrant of Eta.

Tropical Storm Eta will move through an environment more favorable for intensification during the next several days. Eta will move over water where the Sea Surface Temperature is near 28°C. The upper level low over the northwestern Caribbean Sea will produce easterly winds which blow toward the top of Eta’s circulation on Monday. Those winds will cause vertical wind shear, but the shear will slowly decrease. Tropical Storm Eta could move over the Loop Current when it moves west of the Florida Keys. The Sea Surface Temperature of the water in the Loop Current is near 29°C. Eta is likely to strengthen to a hurricane when it moves over the Loop Current.

Counterclockwise rotation around the upper low over the northwestern Caribbean Sea will steer Tropical Storm Eta toward the west during the next 12 hours. Eta will move more toward the southwest on Monday night. Eta could stall for a period on Tuesday. An upper level trough over the western U.S. will move toward the Gulf of Mexico. The upper level trough will start to pull Eta toward the north later in the week. Eta could move toward the west coast of Florida on Wednesday.

Tropical Storm Eta will move across the Lower Florida Keys during the next 12 hours. Eta will produce gusty winds over Keys on Monday. Those winds could cause a storm surge of up to 4 feet (1.3 meters). Bands revolving around the northern side of Tropical Storm Eta will continue to drop heavy rain over parts of South Florida. Urban flooding will occur in some locations and Flash Flood Watches are in effect for South Florida.

Disturbance South of Florida Keys

A disturbance south of the Florida Keys is currently designated at Invest 90L.  The disturbance could develop into a tropical or subtropical cyclone during the next few days.  At 8:00 p.m. EDT on Thursday the center of Invest 90L was located at latitude 23.9°N and longitude 81.2°W which put it about 55 miles (85 km) south of Marathon, Florida.  It was moving toward the east-northeast at 5 m.p.h. (8 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 1013 mb.

A small trough in the middle troposphere moved over a stationary front south of the Florida Keys on Thursday.  Satellite images and radar loops detected rotation in the middle troposphere.  There was a broad counterclockwise rotation south of the Keys and radar loops also revealed several small counterclockwise rotations within the broader mid-level circulation.  However, there did not appear to be a distinct center of circulation with lower pressure at the surface.

Invest 90L is forecast to move toward the northeast during the next several days.  It will move into an environment more favorable for development into a tropical or subtropical cyclone.  Invest 90L will move over water where the Sea Surface Temperature is near 27°C.  There will be an upper level trough over the eastern Gulf of Mexico, but a small upper level ridge will develop east of Florida.  The combination of the upper level trough and the upper ridge will produce a region of upper level divergence east of Florida.  The upper level divergence will pump mass away and the surface pressure will decrease in that area.  A surface low pressure system is likely to form on Friday or Saturday.  The National Hurricane Center is indicating that there is an 80% probability of the formation of a tropical or subtropical cyclone.  A reconnaissance plane is tentatively scheduled to investigate the system on Friday afternoon, if necessary.

Potential Tropical Cyclone Seven Causes Tropical Storm Watch for U.S. Gulf Coast

Potential Tropical Cyclone Seven caused the National Hurricane Center to issue a Tropical Storm Watch for a portion of the U.S. Gulf Coast on Sunday afternoon.  A Tropical Storm Watch was in effect for the portion of the coast from the Alabama-Florida border to Morgan City, Louisiana including Lake Pontchartrain.  At 5:00 p.m. EDT on Sunday the center of Potential Tropical Cyclone Seven was located at latitude 22.7°N and longitude 77.3°W which put it about 275 miles (445 km) east-southeast of Marathon, Florida.  It was moving toward the west-northwest at 15 m.p.h (24 km/h).  The maximum sustained wind speed was 30 m.p.h. (50 km/h) and there were wind gusts to 40 m.p.h. (65 km/h).  The minimum surface pressure was 1012 mb.

Bands of showers and thunderstorms began to form in a tropical wave over the Bahamas and the National Hurricane Center designated the system as Potential Tropical Cyclone Seven in order to be able to issue the Tropical Storm Watch for the north coast of the Gulf of Mexico.  The circulation of Potential Tropical Cyclone Seven was still organizing.  A distinct low level center of circulation had not formed.  Bands of showers and thunderstorms were developing and the bands were starting to revolve around the inner part of the weather system.  Thunderstorms were beginning to generate some upper level divergence.

Potential Tropical Cyclone Seven will be moving into an environment favorable for intensification.  It will move over water where the Sea Surface Temperature is near 30°C.  An upper level ridge is forecast to develop over Potential Tropical Cyclone Seven.  If that occurs, then the upper level winds would be weak and there would be little vertical wind shear.  Potential Tropical Cyclone Seven is forecast to intensify into Tropical Storm Gordon.  If the system moves slowly enough, there is a chance it could strengthen into a hurricane before it reaches the Gulf Coast.

Potential Tropical Cyclone Seven will move around the western end of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer Potential Tropical Cyclone Seven in a general west-northwesterly direction.  On its anticipated track the system will move over the Florida Keys on Monday.  It will be over the eastern Gulf of Mexico on Tuesday and the system could reach the northern Gulf Coast late on Tuesday or early on Wednesday.

Elsewhere over the tropical Atlantic, Tropical Storm Florence was moving quickly away from the Cabo Verde Islands.  At 5:00 p.m. EDT on Sunday the center of Tropical Storm Florence was located at latitude 17.4°N and longitude 34.6°W which put it about 700 miles (1125 km) west of the Cabo Verde Islands.  Florence was moving toward the west-northwest at 15 m.p.h. (24 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1000 mb.