Tropical Storm Marco strengthened on Saturday and a Hurricane Watch was issued for a portion of the central Gulf Coast. At 5:00 p.m. EDT on Saturday the center of Tropical Storm Marco was located at latitude 21.9°N and longitude 68.1°W which put it about 50 miles (80 km) west of the western tip of Cuba. Marco was moving toward the north-northwest at 13 m.p.h. (20 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 992 mb.
A Hurricane Watch was issued for the portion of the coast from Intracoastal City, Louisiana to the Mississippi/Alabama border including Lake Pontchartrain, Lake Maurepas and New Orleans. A Tropical Storm Watch was in effect for the portion of the coast from the Mississippi/Alabama border to the Alabama/Florida border. A Tropical Storm Warning was in effect for the Cuban province of Pinar del Rio.
Tropical Storm Marco exhibited much better organization on Saturday. Weather radar on a reconnaissance plane and from Cuba as well as visible satellite images indicated that a small eye developed at the center of Marco. The eye was surrounded by a ring of thunderstorms and the strongest winds were occurring in that ring of storms. Bands of showers and thunderstorms were revolving around the core of Tropical Storm Marco. Storms near the core were generating upper level divergence which was pumping away to the north of the tropical storm. The circulation around Marco was small. Winds to tropical storm force extended out 100 miles (160 km) to the east of the center of circulation. Winds to tropical storm force only extended out 50 miles (80 km) on the western side of the tropical storm.
Tropical Storm Marco will move through an environment favorable for intensification during the nextt 24 hours. Marco will move over water where the Sea Surface Temperature is near 30°C. It will move east of an upper level trough over the Gulf of Mexico. The trough will produce southwesterly winds which will blow toward the top of the circulation. Those winds will cause some vertical wind shear, but the shear is not likely to be enough to prevent intensification. Tropical Storm Marco is likely to intensify into a hurricane during the next 24 hours. Since he circulation around Marco is small, the tropical storm could strengthen or weaken quickly if the environment changes.
The upper level trough and a subtropical high pressure system over the Atlantic Ocean will steer Tropical Storm Marco toward the north-northwest during the next 36 to 48 hours. On its anticipated track Marco could approach southeastern Louisiana by Monday afternoon. Marco could be a hurricane when it approaches the coast.
Elsewhere, Tropical Storm Laura dropped heavy rain over Puerto Rico and it prompted the issuance of a Tropical Storm Watch for the Florida Keys. At 5:00 p.m. EDT on Saturday the center of Tropical Storm Laura was located at latitude 18.0°N and longitude 68.1°W which put it about 125 miles (200 km) east-southeast of Santo Domingo, Dominican Republic. Laura was moving toward the west at 18 m.p.h. (30 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 1004 mb.
Tropical Storm Warnings were in effect for the U.S. Virgin Islands, Puerto Rico, Vieques and Culebra. A Tropical Storm Warning was in effect for the northern coast of Hispaniola from Le Mole St. Nicholas, Haiti to Cabo Engano, Dominican Republic. Tropical Storm Warnings were in effect for the Turks and Caicos, the Acklins, Long Key, Crooked Island, the Inaguas, and the Ragged Islands. A Tropical Storm Warning was also in effect for the Cuban provinces of Las Tunas, Holguin, Santiago de Cuba, Guantanamo and Granma.
A Tropical Storm Watch was issued for the Florida Keys from Ocean Reef to Key West. Tropical Storm Watches were in effect for the Central Bahamas and for Andros Island.
Tropical Storm Marco is forecast to move over HIspaniola and the mountains there are likely to disrupt the circulation.