Former Tropical Depression Fourteen strengthened into Tropical Storm Marco over the northwestern Caribbean Sea on Friday night. At 11:00 p.m. EDT on Friday the center of Tropical Storm Marco was located at latitude 18.7°N and longitude 84.9°W which puts it about 180 miles (290 km) southeast of Cozumel, Mexico. Marco was moving toward the north-northwest at 13 m.p.h. (20 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1003 mb.
A Hurricane Watch was in effect for the portion of the coast from Punta Herrero to Cancun, Mexico. A Tropical Storm Warning was in effect for the portion of the coast from Punta Herrero to Dzilam, Mexico.
An Air Force Reserve Hurricane Hunter reconnaissance aircraft found winds to tropical storm force in former Tropical Depression Fourteen and the National Hurricane Center upgraded the system to Tropical Storm Marco. More thunderstorms developed near the center of Marco. Many of the thunderstorms were occurring in short bands northeast of the center of circulation. The strongest winds were occurring in those bands. Storms near the center were generating upper level divergence which was pumping mass away to the northeast of the tropical storm. Winds to tropical storm force extended 80 miles (130 km) to the northeast of Marco. The winds in the other parts of the tropical storm were blowing at less than tropical storm force.
Tropical Storm Marco will move through an environment favorable for intensification during the next 24 hours. Marco will move over water where the Sea Surface Temperature is near 29°C. It will move east of a large upper level trough over the Gulf of Mexico. The trough will produce southwesterly winds which will blow toward the top of Tropical Storm Marco. Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent intensification. Marco will intensify on Saturday and it could strengthen quickly because the circulation is small. Tropical Storm Marco could also weaken quickly if the center moves over the Yucatan Peninsula.
Tropical Storm Marco will move around the western end of a subtropical high pressure system over the Atlantic Ocean. The high and the upper level trough will interact to steer Marco toward the northwest during the next 24 to 36 hours. On its anticipated track the center of Tropical Storm Marco could pass near the northeastern part of the Yucatan Peninsula on Saturday.
Elsewhere over the Atlantic Ocean, disorganized Tropical Storm Laura sped across the northern Leeward Islands on Friday. At 11:00 p.m. EDT on Friday the center of Tropical Storm Laura was located at latitude 17.0°N and longitude 84.9°W which put it about 195 miles (315 km) east-southeast of San Juan, Puerto Rico. Laura was moving toward the west-northwest at 18 m.p.h. (30 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 1008 mb.
Tropical Storm Warnings were in effect Saba, St. Eustatius, St. Maarten, St. Martin, St. Barthelemy, the British Virgin Islands, the U.S. Virgin Islands, Puerto Rico, Vieques, Culebra, the north coast of HIspaniola from Le Mole St. Nicholas, Haiti to Cabo Engano, Dominican Republic, the Turks and Caicos, the Acklins, Crooked Island, Long Cay, the Inaguas, and the Ragged Islands. A Tropical Storm Watch was in effect for the Central Bahamas.