Marco Enters the Gulf of Mexico; Storm Surge & Hurricane Watches Issued for Portions of the Northern Gulf Coast

NHC UPDATE SUMMARY OF 7:00 PM CDT INFORMATION

LOCATION…22.3N 86.0W
ABOUT 75 MI…120 KM WNW OF THE WESTERN TIP OF CUBA
ABOUT 510 MI…820 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS…65 MPH…100 KM/H
PRESENT MOVEMENT…NNW OR 340 DEGREES AT 13 MPH…20 KM/H
MINIMUM CENTRAL PRESSURE…994 MB…29.35 INCHES

WATCHES AND WARNINGS

A Storm Surge Watch is in effect for…
* Sabine Pass to the Alabama/Florida border
* Lake Pontchartrain, Lake Maurepas, Lake Borgne, and Mobile Bay

A Hurricane Watch is in effect for…
* Intracoastal City Louisiana to the Mississippi/Alabama border
* Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans

A Tropical Storm Warning is in effect for…
* Province of Pinar del Rio Cuba

A Tropical Storm Watch is in effect for…
* Mississippi/Alabama border to the Alabama/Florida border

DISCUSSION AND OUTLOOK

At 700 PM CDT (0000 UTC), the center of Tropical Storm Marco was located by an Air Force Reserve Hurricane Hunter Aircraft near latitude 22.3 North, longitude 86.0 West. Marco is moving toward the north-northwest near 13 mph (20 km/h). Marco is expected to continue moving toward the north-northwest across the central Gulf of Mexico on Sunday and is forecast to reach the northern Gulf coast on Monday. After moving inland, Marco is expected to slow down and turn toward the northwest and west-northwest Monday night and Tuesday, moving across southern Louisiana and east Texas.

Maximum sustained winds based on preliminary data from the reconnaissance aircraft are near 65 mph (100 km/h) with higher gusts. Strengthening is forecast during the next day or two, and Marco is expected to become a hurricane later tonight or on Sunday. Marco is likely to still be at or near hurricane strength when it reaches the northern Gulf coast on Monday. Weakening is forecast to occur while the center moves farther inland Monday night and Tuesday.

Tropical-storm-force winds extend outward up to 90 miles (150 km) from the center.

The latest minimum central pressure reported by the hurricane hunter plane was 994 MB (29.35 inches).

HAZARDS AFFECTING LAND

STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide…

Grand Isle LA to the AL/FL Border including Lake Borgne and Mobile Bay…3-5 ft
Lake Pontchartrain and Lake Maurepas…2-4 ft
Sabine Pass to Grand Isle LA…2-4 ft

The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large and destructive waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle and can vary greatly over short distances. For information specific to your area, please see products issued by your local National Weather Service forecast office.

WIND: Hurricane conditions are possible within the hurricane watch area by midday Monday, with tropical storm conditions possible by early Monday. Tropical storm conditions are possible within the tropical storm watch area on Monday.

Tropical storm conditions are expected to continue within the warning area in Cuba through this evening.

RAINFALL: Marco is expected to produce the following rainfall accumulations through Monday:

Far western Cuba: 2 to 4 inches of rain, with isolated maximum amounts of 6 inches possible

Eastern portions of the Mexican states of Quintana Roo and Yucatan: 1 to 3 inches.

Central U.S. Gulf Coast: 1 to 3 inches, isolated maximum amounts of 5 inches.

This rainfall may result in areas of flash and urban flooding along the Central U.S. Gulf Coast.

Category: ALL POSTS, Severe Weather, Tropical