1. Hurricane conditions, life-threatening storm surge, and heavy rainfall are expected from Marco along portions of the Gulf Coast beginning on Monday, and Hurricane and Storm Surge Warnings have been issued. Interests in these areas should follow any advice given by 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 the middle of next week. This could result in a prolonged period of hazardous weather for areas that may also be affected by Marco. Interests there should monitor the progress of Marco and Laura and updates to the forecast during the next few days.

ISSUED FOR PORTIONS OF THE NORTHERN GULF COAST...

SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION LOCATION...23.7N 87.0W ABOUT 185 MI...295 KM NW OF THE WESTERN TIP OF CUBA ABOUT 395 MI...635 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H PRESENT MOVEMENT...NNW OR 335 DEGREES AT 13 MPH...20 KM/H MINIMUM CENTRAL PRESSURE...994 MB...29.36 INCHES

WATCHES AND WARNINGS CHANGES WITH THIS ADVISORY:

A Storm Surge Warning has been issued from Morgan City Louisiana to Ocean Springs Mississippi.

A Hurricane Warning has been issued for the coast of Louisiana from Morgan City to the Mouth of the Pearl River.

A Tropical Storm Warning has been issued for Louisiana for Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans

The Hurricane Watch from the Mouth of the Pearl River to the Mississippi/Alabama border has been changed to a Tropical Storm Warning.

The Tropical Storm Warning has been discontinued for the province of Pinar del Rio Cuba for Marco.

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 Hurricane Warning is in effect for...
- Morgan City Louisiana to the Mouth of the Pearl River

A Storm Surge Watch is in effect for...
- Sabine Pass to Morgan City Louisiana
- Ocean Springs to the Alabama/Florida border
- Lake Pontchartrain, Lake Maurepas, and Mobile Bay

A Hurricane Watch is in effect for...
- Intracoastal City Louisiana to west of Morgan City
- Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans

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

A Tropical Storm Watch is in effect for...
- Mississippi/Alabama border to the Alabama/Florida border

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 Hurricane Warning means that hurricane conditions are expected somewhere within the warning area. A warning is typically issued 36 hours before the anticipated first occurrence of tropicalstormforce winds, conditions that make outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion.

A Storm Surge Watch means there is a possibility of life threatening inundation, from rising water moving inland from the coastline, in the indicated locations during the next 48 hours. For a depiction of areas at risk, please see the National Weather Service Storm Surge Watch/Warning Graphic, available at hurricanes.gov.

A Hurricane Watch means that hurricane conditions are possible within the watch area.

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.

A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours.

For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service.

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...

Sabine Pass to Morgan City...24 ft Morgan City to Ocean Springs including Lake Borgne...46 ft Ocean Springs to the AL/FL Border including Mobile Bay...24 ft Lake Pontchartrain and Lake Maurepas...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 destructive 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: Hurricane conditions are expected within the hurricane warning 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, and hurricane conditions are possible within the hurricane watch areas late on Monday.

RAINFALL: Marco is expected to produce rainfall accumulations of 2 to 4 inches with isolated maximum amounts of 6 inches across the Central U.S. Gulf coast through Tuesday.

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

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

TORNADOES: An isolated tornado will be possible early Monday morning near the southeast Louisiana coast.

At 400 AM CDT (0900 UTC), the center of Tropical Storm Marco was located near latitude 23.7 North, longitude 87.0 West. Marco is moving toward the northnorthwest near 13 mph (20 km/h). Marco is forecast to continue moving northnorthwestward across the central Gulf of Mexico today and will approach southeastern Louisiana on Monday. A gradual turn toward the west with a decrease in forward speed is expected after Marco moves inland on Monday and on Tuesday.

Maximum sustained winds are near 70 mph (110 km/h) with higher gusts. Some strengthening is anticipated and Marco is forecast to become a hurricane today. Marco is expected to be a hurricane when it approaches the northern Gulf Coast on Monday. Rapid weakening is expected after Marco moves inland.

Tropicalstormforce winds extend outward up to 60 miles (95 km) from the center.

The estimated minimum central pressure based on data from the Air Force reconnaissance plane is 994 mb (29.36 inches).

Thunderstorm bursts continue to fire near the center of Marco, then weaken an hour or two later due to persistent shear. Overall, the storm's appearance hasn't changed with nearly all of the deep convection very near or northeast of the center. Although the satellite presentation is somewhat lacking at the moment, the earlier Air Force Reserve Hurricane Hunter mission found believable SFMR values to 60 kt, so that value remains the initial wind speed.

The intensity forecast remains tricky with Marco due to its small size and marginal environment. There are some models that briefly relax the shear today, which will likely be enough of a change to allow Marco to reach hurricane strength. Later on, while the cyclone is near the coast of Louisiana, the shear is forecast to increase, but it is unknown exactly how close to landfall this will occur. Our best forecast at this time is that the strongest winds will be confined to the coast, and that Marco will then weaken faster than most hurricanes do over the swamps of Louisiana due to the shear. No significant changes were made to the intensity forecast, which is very close to the model consensus. The new forecast necessitates the issuance of hurricane warnings for portions of southeastern Louisiana.

Marco continues moving north-northwestward or 335/11 kt. Thisgeneral track and speed is likely today, with a turn to thenorthwest and decrease in forward speed expected as the stormweakens late Monday. While the track forecast is essentiallyunchanged from the previous one, there is still a fair bit ofspread in the model guidance, likely tied to the intensityforecast. The stronger guidance is near or northeast of the newmodel consensus, due to the upper-level flow, and the NHC forecast leans in that direction, close to the previous official prediction.