Hurricane Marco Tropical Cyclone Update
NWS National Hurricane Center Miami FL AL142020
1130 AM CDT Sun Aug 23 2020
…MARCO BECOMES A HURRICANE…
…LIFE-THREATENING STORM SURGE AND HURRICANE-FORCE WINDS EXPECTED
ALONG PORTIONS OF THE U.S. GULF COAST…
Data from an Air Force Reserve Hurricane Hunter aircraft indicate
that Marco has strengthened into a hurricane with maximum winds of
75 mph (120 km/h) with higher gusts.
SUMMARY OF 1130 AM CDT…1630 UTC…INFORMATION
———————————————-
LOCATION…25.0N 87.4W
ABOUT 300 MI…480 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 460 MI…740 KM SE OF LAFAYETTE LOUISIANA
MAXIMUM SUSTAINED WINDS…75 MPH…120 KM/H
PRESENT MOVEMENT…NNW OR 340 DEGREES AT 14 MPH…22 KM/H
MINIMUM CENTRAL PRESSURE…992 MB…29.29 INCHEs
BULLETIN
Tropical Storm Marco Advisory Number 13
NWS National Hurricane Center Miami FL AL142020
1000 AM CDT Sun Aug 23 2020
…MARCO EXPECTED TO BECOME A HURRICANE TODAY AS IT ENTERS
THE CENTRAL GULF OF MEXICO…
…LIFE-THREATENING STORM SURGE AND HURRICANE-FORCE WINDS EXPECTED
ALONG PORTIONS OF THE U.S. GULF COAST…
SUMMARY OF 1000 AM CDT…1500 UTC…INFORMATION
———————————————–
LOCATION…24.7N 87.3W
ABOUT 325 MI…520 KM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 475 MI…765 KM SE OF LAFAYETTE LOUISIANA
MAXIMUM SUSTAINED WINDS…70 MPH…110 KM/H
PRESENT MOVEMENT…NNW OR 340 DEGREES AT 14 MPH…22 KM/H
MINIMUM CENTRAL PRESSURE…993 MB…29.33 INCHES
WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY:
The Storm Surge Watch has been discontinued from the
Mississippi/Alabama border to the Alabama/Florida border, including
Mobile Bay.
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 Mississippi to the Mississippi/Alabama border
* Lake Pontchartrain and Lake Maurepas
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 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 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
tropical-storm-force 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.
DISCUSSION AND OUTLOOK
———————-
At 1000 AM CDT (1500 UTC), the center of Tropical Storm Marco was
located near latitude 24.7 North, longitude 87.3 West. Marco is
moving toward the north-northwest near 14 mph (22 km/h), and this
motion is expected to continue through tonight, followed by a turn
to the northwest by Monday. On the forecast track, Marco will cross
the central Gulf of Mexico today and will approach southeastern
Louisiana on Monday. A gradual turn toward the west-northwest with
a decrease in forward speed is expected after Marco moves inland.
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 later today and be at hurricane strength when it
approaches the northern Gulf Coast on Monday. Rapid weakening is
expected after Marco moves inland.
Tropical-storm-force winds extend outward up to 70 miles (110 km)
from the center.
The estimated minimum central pressure is 993 mb (29.33 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…4-6 ft
Sabine Pass to Morgan City LA…2-4 ft
Ocean Springs MS to the MS/AL Border…2-4 ft
Lake Pontchartrain and Lake Maurepas…2-4 ft
MS/AL Border to 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 expected within the hurricane
warning 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
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 life-threatening 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.