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Tropical Storm Marco Intermediate Advisory Number 16A
NWS National Hurricane Center Miami FL AL142020
700 AM CDT Mon Aug 24 2020
...MARCO PRODUCING HEAVY RAINFALL AND GUSTY WINDS ALONG PORTIONS OF
THE NORTHERN GULF COAST...
SUMMARY OF 700 AM CDT...1200 UTC...INFORMATION
ABOUT 85 MI...135 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS...50 MPH...80 KM/H
PRESENT MOVEMENT...NW OR 325 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
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...
* Intracoastal City to the Mississippi/Alabama border
* Lake Pontchartrain, Lake Maurepas, and Metropolitan New Orleans
A Storm Surge Warning means there is a danger of life-threatening
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 life-threatening 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 12
to 24 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.
DISCUSSION AND OUTLOOK
At 700 AM CDT (1200 UTC), the center of Tropical Storm Marco was
located near latitude 28.1 North, longitude 88.4 West. Marco is
moving toward the northwest near 10 mph (17 km/h). Marco is
forecast to approach the coast of Louisiana this afternoon, and then
turn westward and move very close to the coast of Louisiana through
Data from an Air Force Reserve Hurricane Hunter aircraft indicate
that maximum sustained winds have decreased to near 50 mph (80 km/h)
with higher gusts. Further weakening is expected, and Marco is
forecast to become a tropical depression late on Tuesday and
dissipate on Wednesday.
Tropical-storm-force winds extend outward up to 105 miles (165 km),
primarily northeast of the center.
The estimated minimum central pressure is 1005 mb (29.68 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 Ocean Springs MS, including Lake Borgne...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
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
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 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 in the 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 life-threatening surf and rip current
conditions. Please consult products from your local weather office.
TORNADOES: A couple of tornadoes will be possible today from
southeast Louisiana to the western Florida Panhandle.
Next complete advisory at 1000 AM CDT.