Marco Strengthens to a Hurricane, Laura Drenches Hispaniola

Former Tropical Storm Marco strengthened into a hurricane on Sunday over the Gulf of Mexico while Tropical Storm Laura dropped drenching rain on Hispaniola.  At 2:00 p.m. EDT on Sunday the center of Hurricane Marco was located at latitude 25.3°N and longitude 87.4°W which put it about 280 miles (450 km) south-southeast of the Mouth of the Mississippi River.  Marco was moving toward the north-northwest at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h).  The minimum surface pressure was 992 mb.

A Hurricane Warning was in effect for the portion of the coast from Morgan City, Louisiana to the Mouth of the Pearl River, Mississippi.  Hurricane Watches were in effect for the portion of the coast from Intracoastal City, Louisiana to Morgan City and for New Orleans, Lake Pontchartrain and Lake Maurepas.  A Tropical Storm Warning was in effect from the Mouth of the Pearl River to the Mississippi/Alabama border.  A Tropical Storm Watch was in effect for the portion of the coast from the Mississippi/Alabama border to the Alabama/Florida border.

Former Tropical Storm Marco strengthened into a hurricane on Sunday.  A small eye developed at the center of circulation.  A ring of thunderstorms surrounded eye and the strongest winds were occurring in that ring of storms.  Bands of showers and thunderstorms were revolving around the core of Marco.  Storms near the core generated upper level divergence which pumped mass away to the northeast of the hurricane.

The circulation around Hurricane Marco was small.  Winds to hurricane force extended out 15 miles (25 km) from the center of circulation.  Winds to tropical storm force extended out 70 miles (110 km) from the center.

Hurricane Marco will move through an environment somewhat favorable for intensification during the next 18 hours.  Marco will move over water where the Sea Surface Temperature is near 30°C.  An upper level trough over the northwestern Gulf of Mexico will produce southwesterly winds which will blow toward the top of Hurricane Marco.  Those winds will cause some vertical wind shear, but the shear will not be strong enough to prevent Marco from strengthening during the next 18 hours.

The upper level trough and a subtropical high pressure system over the Atlantic Ocean will steer Hurricane Marco toward the north-northwest during the next day or so.  On its anticipated track Hurricane Marco will approach southeast Louisiana on Monday.  Marco will bring gusty winds and drop locally heavy rain over southeastern Louisiana and southern Mississippi.

Elsewhere, Tropical Storm Laura dropped heavy rain on the Dominican Republic and Haiti.  There were reports of flash floods.  At 2:00 pm. EDT on Sunday the center of Tropical Storm Laura was located at latitude 19.4°N and longitude 74.3°W which put it about 80 miles (130 km) southeast of Guantanamo, Cuba.  Laura was moving toward the west-northwest at 21 m.p.h. (33 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 portion of the northern coast of the Dominican Republic from Samana to the border with Haiti and for the entire coast of Haiti.  Tropical Storm Warnings were in effect for the Turks and Caicos, the Acklins, Crooked Island, Long Cay, the Inaguas, and the Ragged Islands.  Tropical Storm Warnings were also in effect for the Cuban provinces of Las Tunas, Holguin, Guantanamo, Santiago de Cuba, Granma, Ciego de Avila, Sancti Spiritus, Villa Carla, Cienfuegos, Matanzas, Mayabeque, La Habana, Artemisa, Pinar del Rio and the Isle of Youth.  A Tropical Storm Watch was in effect for the Florida Keys to the Isle of Youth.  Tropical Storm Watches were also in effect for the Central Bahamas and Andros Island.