1. Gusty winds, dangerous storm surge, and heavy rainfall areexpected from Marco along portions of the Gulf Coast beginninglater today. Interests in these areas should follow any advice givenby local government officials.

2. Tropical Storm Laura could bring additional storm surge,rainfall, and wind impacts to portions of the U.S. Gulf Coast by themiddle of the week. This could result in a prolonged period ofhazardous weather for areas that may also be affected by Marco.Interests there should monitor the progress of Marco and Laura andupdates to the forecast during the next few days.

CHANGES WITH THIS ADVISORY:

The Tropical Storm Warning from west of Morgan City to Intracoastal City, Louisiana, has been discontinued.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for....
- Morgan City Louisiana to Ocean Springs Mississippi
- Lake Borgne

A Tropical Storm Warning is in effect for...
- Morgan City to the Mississippi/Alabama border
- Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans

A Storm Surge Warning means there is a danger of lifethreatening inundation, from rising water moving inland from the coastline, during the next 36 hours in the indicated locations. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov. This is a lifethreatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials.

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case within the next 6 to 18 hours.

For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office.

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...

Morgan City LA to Ocean Springs MS, including Lake Borgne...24 ft

The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large and dangerous waves. Surgerelated 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: Tropical storm conditions are expected to start by this afternoon in portions of the warning area.

RAINFALL: Marco is expected to produce total rainfall accumulations of 3 to 6 inches with isolated maximum amounts of 10 inches across portions of the northeast and northcentral Gulf coast through Tuesday. This rainfall may result in areas of flash, urban and small stream flooding along the same area.

SURF: Swells generated by Marco are likely to affect portions of the northern Gulf Coast for the next couple of days. These swells are likely to cause lifethreatening surf and rip current conditions. Please consult products from your local weather office.

TORNADOES: A couple of tornadoes are possible today into tonight across the Florida Panhandle, southern Georgia, southern Alabama, and southern Mississippi.

At 1000 AM CDT (1500 UTC), the center of Tropical Storm Marco was located near latitude 28.5 North, longitude 88.5 West. Marco is moving toward the northnorthwest near 8 mph (13 km/h). A turn to the westnorthwest is expected to occur by Tuesday, and this motion should continue until the system dissipates in a couple of days.

Maximum sustained winds are near 50 mph (85 km/h) with higher gusts. Steady weakening is forecast, and Marco is expected to weaken to a tropical depression tonight, and degenerate to a remnant low on Tuesday.

Tropicalstormforce winds extend outward up to 105 miles (165 km) from the center.

The estimated minimum central pressure is 1006 mb (29.71 inches).

Strong southwesterly shear is taking its toll on Marco, with the edge of the nearest deep convection now displaced 50 n mi northeast of the exposed circulation center. Data from an Air Force Reserve Hurricane Hunter aircraft that investigated the system this morning measured 45-kt surface winds with the onboard SFMR instrument in that convection, but winds of only 20 to 30 kt were measured between this thunderstorm activity and the cyclone's center. Sampling by the aircraft has also revealed that winds of tropical storm force are likely no longer occurring in any portion of the circulation except in that convection. Based on the SFMR data, the initial intensity is initialized at 45 kt.

The shear is not forecast to abate in the foreseeable future, and the simulated satellite imagery in the GFS and ECMWF suggests that Marco will degenerate into a remnant low on Tuesday. The latest NHC forecast is near the various consensus aids, which shows the cyclone weakening to a tropical depression late tonight. Based on the updated intensity forecast, tropical storm conditions are no longer expected to be produced by Marco over the central portions of the Louisiana coast, and the Tropical Storm Warnings for those locations have been discontinued.

Marco has slowed down and has moved a little to the right of the forecast track over the past few hours, with an initial motion of NNW/7 kt. The track guidance for the entire forecast period has shifted back northward, and is just south of where it was this time yesterday. The official forecast track was adjusted eastward in the near term to accommodate the recent right-of-track bias. After 12 h, the track forecast lies between the previous one and most of the consensus track guidance. On this track, Marco is expected to move inland tonight, and remain inland when the system turns west-northwestward in the low-level flow by Tuesday morning.