BULLETIN
Tropical Storm Laura Advisory Number 20
NWS National Hurricane Center Miami FL AL132020
500 PM EDT Mon Aug 24 2020
…CENTER OF LAURA PASSING NEAR THE ISLE OF YOUTH….
…HURRICANE AND STORM SURGE WATCHES ISSUED FOR A PORTION OF THE
NORTHWEST GULF COAST…
SUMMARY OF 500 PM EDT…2100 UTC…INFORMATION
———————————————-
LOCATION…21.7N 82.2W
ABOUT 40 MI…65 KM E OF THE ISLE OF YOUTH
ABOUT 175 MI…280 KM E OF THE WESTERN TIP OF CUBA
MAXIMUM SUSTAINED WINDS…60 MPH…95 KM/H
PRESENT MOVEMENT…WNW OR 290 DEGREES AT 20 MPH…31 KM/H
MINIMUM CENTRAL PRESSURE…1001 MB…29.56 INCHES
WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY:
A Storm Surge Watch is in effect from San Luis Pass, Texas, to Ocean
Springs, Mississippi, including Lake Pontchartrain, Lake Maurepas,
and Lake Borgne for areas outside of the southeast Louisiana
Hurricane and Storm Damage Risk Reduction System.
A Hurricane Watch is in effect from Port Bolivar, Texas, to
west of Morgan City, Louisiana.
A Tropical Storm Watch is in effect from south of Port Bolivar to
San Luis Pass Texas and from Morgan City to the Mouth of the
Mississippi River.
The Tropical Storm Warning for Little Cayman and Cayman Brac has
been discontinued.
The Tropical Storm Warning for the Cuban provinces of Camaguey and
Las Tunas has been discontinued.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Storm Surge Watch is in effect for…
* San Luis Pass Texas to Ocean Springs Mississippi
* Lake Pontchartrain, Lake Maurepas, and Lake Borgne
A Hurricane Watch is in effect for…
* Port Bolivar Texas to west of Morgan City Louisiana
A Tropical Storm Warning is in effect for…
* Cuban provinces of Ciego De Avila, Sancti Spiritus, Villa Clara,
Cienfuegos, Matanzas, Mayabeque, La Habana, Artemisa, Pinar del
Rio, and the Isle of Youth
* Florida Keys from Craig Key to Key West
* Dry Tortugas
A Tropical Storm Watch is in effect for…
* South of Port Bolivar to San Luis Pass Texas
* Morgan City Louisiana to the Mouth of the Mississippi River
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 watch is typically issued 48 hours
before the anticipated first occurrence of tropical-storm-force
winds, conditions that make outside preparations difficult or
dangerous.
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area.
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 500 PM EDT (2100 UTC), the center of Tropical Storm Laura was
located near latitude 21.7 North, longitude 82.2 West. Laura is
moving toward the west-northwest near 20 mph (31 km/h), and this
general motion with some decrease in forward speed is expected over
the next day or so. A turn toward the northwest is forecast by
Wednesday, and a northwestward to north-northwestward motion should
continue through Wednesday night. On the forecast track, the center
of Laura will cross western Cuba this evening and move into the
southeastern Gulf of Mexico overnight. Laura is then forecast to
move over the central and northwestern Gulf of Mexico Tuesday night
and Wednesday, and approach the northwestern coast of the Gulf of
Mexico Wednesday night.
Maximum sustained winds are near 60 mph (95 km/h) with higher gusts.
Strengthening is expected when the storm moves over the Gulf of
Mexico, and Laura is foreast to become a hurricane by late Tuesday.
Additional strengthening is forecast on Wednesday.
Tropical-storm-force winds extend outward up to 175 miles (280 km)
primarily to the northeast and east of the center.
The estimated minimum central pressure is 1001 mb (29.56 inches).
HAZARDS AFFECTING LAND
———————-
Key messages for Laura can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT3 and WMO header WTNT43 KNHC.
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…
High Island TX to Morgan City LA including Sabine Lake, Calcasieu
Lake, and Vermilion Bay…7-11 ft
Port Bolivar TX to High Island TX…4-6 ft
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
San Luis Pass TX to Port Bolivar TX…2-4 ft
Galveston Bay…2-4 ft
Lake Pontchartrain and Lake Maurepas…2-4 ft
The deepest water will occur along the immediate coast near and to
the right of the landfall location, where the surge will be
accompanied by large and destructive 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.
RAINFALL: Laura is expected to produce the following storm total
rainfall accumulations into tonight:
Western Jamaica, Western Cuba and the Cayman Islands: 4 to 6 inches,
with maximum amounts of 10 inches. Across the Greater Antilles this
heavy rainfall could lead to life-threatening flash and urban
flooding, and the potential for mudslides.
From Wednesday afternoon into Saturday, Laura is expected to produce
rainfall of 4 to 8 inches, with isolated maximum amounts of 12
inches across portions of the west-central U.S. Gulf Coast near the
Texas and Louisiana border north into portions of the lower
Mississippi Valley. This rainfall could cause widespread flash and
urban flooding, small streams to overflow their banks, and minor to
isolated moderate river flooding.
WIND: Tropical storm conditions are expected to spread westward
within the warning area in western Cuba through this evening.
Tropical storm conditions are also expected within the warning area
in the middle and lower Florida Keys and the Dry Tortugas tonight.
Hurricane conditions are possible in the hurricane watch area along
the Gulf Coast by late Wednesday, with tropical storm conditions
possible by Wednesday afternoon.
SURF: Swells generated by Laura are affecting portions of Cuba, the
central Bahamas, and the Florida Keys. Swells are expected to
spread northward along portions of the west coast of Florida
peninsula and the coast of the Florida panhandle on Tuesday
and Tuesday night, and reach the northern and northwest Gulf coast
by Wednesday. 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 is possible through tonight across
the Florida Keys.