Marco Has Weakened to Tropical Storm Status as of 10:00 pm

NHC UPDATE SUMMARY OF 10:00 PM CDT INFORMATION

LOCATION…26.8N 87.6W
ABOUT 185 MI…295 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS…70 MPH…110 KM/H
PRESENT MOVEMENT…NNW OR 345 DEGREES AT 12 MPH…19 KM/H
MINIMUM CENTRAL PRESSURE…1000 MB…29.53 INCHES

WATCHES AND WARNINGS

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 Mississippi to the Mississippi/Alabama border
* Lake Pontchartrain and Lake Maurepas

A Hurricane Watch is in effect for…
* 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
* Cameron to west of Morgan City

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

DISCUSSION AND OUTLOOK

At 1000 PM CDT (0300 UTC), the center of Tropical Storm Marco was located by an Air Force Reserve Hurricane Hunter plane near latitude 26.8 North, longitude 87.6 West. Marco is moving toward the north-northwest near 12 mph (19 km/h). A continued north-northwestward motion is possible tonight, but a turn toward the northwest is expected by Monday morning. Marco is forecast to approach the coast of Louisiana by Monday afternoon, and then turn westward and move near or over the coast through Tuesday.

Data from the Hurricane Hunter plane indicate that maximum sustained winds have decreased to near 70 mph (110 km/h) with higher gusts. Fluctuations in intensity are possible during the next 24 hours, but Marco is forecast to weaken rapidly by early Tuesday.

Tropical-storm-force winds extend outward up to 70 miles (110 km) from the center.

The estimated minimum central pressure based on data from the reconnaissance aircraft is 1000 MB (29.53 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…

Morgan City LA to Mouth of the Mississippi River…4-6 ft
Mouth of the Mississippi River to Ocean Springs MS including Lake Borgne…3-5 ft
Lake Pontchartrain and Lake Maurepas…2-4 ft
Intracoastal City LA to Morgan City LA…2-4 ft
Sabine Pass to Intracoastal City…1-3 ft
Ocean Springs MS to the AL/FL Border including Mobile Bay…1-3 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. 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 still possible within the hurricane warning area by midday Monday, with tropical storm conditions likely by midday 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 Monday.

RAINFALL: Marco is expected to produce total rainfall accumulations of 3 to 5 inches with isolated maximum amounts of 10 inches across portions of the northeast and north-central Gulf coast through Tuesday.

This rainfall may result in areas of flash, urban and small stream flooding along the central U.S. Gulf Coast.

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 life-threatening surf and rip current conditions. Please consult products from your local weather office.

TORNADOES: Isolated tornadoes are possible across southeast Louisiana, southern Mississippi, southern Alabama, and the Florida Panhandle Monday and Monday night.

Category: ALL POSTS, Severe Weather, Tropical