[Tropical] Public Tropical Cyclone Advisory

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WTNT33 KNHC 270844
TCPAT3

BULLETIN
Hurricane Laura Advisory Number  30
NWS National Hurricane Center Miami FL       AL132020
400 AM CDT Thu Aug 27 2020

...LAURA MOVING NORTHWARD OVER SOUTHWESTERN LOUISIANA...
...CATASTROPHIC STORM SURGE, EXTREME WINDS, AND FLASH FLOODING
CONTINUES IN PORTIONS OF LOUISIANA...


SUMMARY OF 400 AM CDT...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...30.5N 93.4W
ABOUT 30 MI...50 KM NNW OF LAKE CHARLES LOUISIANA
ABOUT 50 MI...80 KM NE OF PORT ARTHUR TEXAS
MAXIMUM SUSTAINED WINDS...120 MPH...195 KM/H
PRESENT MOVEMENT...N OR 355 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...948 MB...28.00 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

The Storm Surge Warning west of High Island, Texas has been
discontinued.

The Tropical Storm Warning from San Luis Pass to High Island, Texas
has been discontinued.

The Hurricane Watch from east of Intracoastal City to west of
Morgan City Louisiana has been canceled.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for...
* High Island Texas to the Mouth of the Mississippi River

A Hurricane Warning is in effect for...
* High Island Texas to Intracoastal City Louisiana

A Tropical Storm Warning is in effect for...
* East of Intracoastal City Louisiana to the Mouth of the
Mississippi River

A Storm Surge Warning means there is a danger of life-threatening
inundation, from rising water moving inland from the coastline 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.  Preparations to protect life
and property should be rushed to completion.

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.

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 400 AM CDT (0900 UTC), the center of Hurricane Laura was located
near latitude 30.5 North, longitude 93.4 West. Laura is moving
toward the north near 15 mph (24 km/h) and this motion should
continue through the day.  A northeastward to east-northeastward
motion is expected tonight and Friday.  On the forecast track, Laura
will move across southwestern Louisiana this morning, and then
continue northward across the state through this afternoon. The
center of Laura is forecast to move over Arkansas tonight, the
mid-Mississippi Valley on Friday, and the mid-Atlantic states on
Saturday.

Maximum sustained winds are near 120 mph (195 km/h) with higher
gusts.  Laura is a category 3 hurricane on the Saffir-Simpson
Hurricane Wind Scale.  Rapid weakening is forecast, and Laura is
expected to become a tropical storm later today.

Hurricane-force winds extend outward up to 60 miles (95 km) from the
center and tropical-storm-force winds extend outward up to 175 miles
(280 km).  An observation in Chennault, Louisiana, recently
reported sustained winds of 76 mph (122 km/h) and a wind gust of 93
mph (150 km/h).

The estimated minimum central pressure is 948 mb (28.00 inches).
An unofficial observation of 948 mb (28.00 inches) was recently
measured in the eye of Laura.


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...

Johnson Bayou to Rockefeller Wildlife Refuge including Calcasieu
Lake...15-20 ft
Rockefeller Wildlife Refuge to Intracoastal City...10-15 ft
Intracoastal City to Morgan City including Vermilion Bay...8-12 ft
Sea Rim State Park to Johnson Bayou including Sabine Lake...4-8 ft
Morgan City to Mouth of the Mississippi River...4-7 ft
High Island to Sea Rim State Park...2-4 ft
Mouth of the Mississippi River to Ocean Springs including Lake
Borgne...1-3 ft
Lake Pontchartrain and Lake Maurepas...1-3 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.

Unsurvivable storm surge with large and destructive waves will cause
catastrophic damage from Sea Rim State Park, Texas, to Intracoastal
City, Louisiana, including Calcasieu and Sabine Lakes. This surge
could penetrate up to 40 miles inland from the immediate coastline,
and flood waters will not fully recede for several days after the
storm.

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 in the hurricane warning
area through the morning, with catastrophic wind damage
expected near Laura's eyewall.  Tropical storm conditions will
spread northward within the warning areas through the day.

Hurricane-force winds and damaging wind gusts are also expected to
spread well inland into portions of eastern Texas and western
Louisiana this morning.

RAINFALL: Through Friday, Laura is expected to produce the following
rainfall totals:

Across portions of Louisiana, Mississippi, across Arkansas: 6 to 12
inches with isolated totals of 18 inches.

This rainfall will cause widespread flash and urban flooding, small
streams and creeks to overflow their banks, and minor to moderate
freshwater river flooding.

Through Saturday, Laura is expected to produce 1 to 3 inches with
isolated maximum amounts of 5 inches across the mid-Mississippi
Valley and portions of the Tennessee and Lower Ohio Valley, the
central Appalachians and the Mid-Atlantic States.

This rainfall may lead to flash and urban flooding and rapid rises
on small streams.

TORNADOES:  Tornadoes are possible today and tonight over parts of
Louisiana, Arkansas, and western Mississippi.

SURF:  Swells produced by Laura are affecting the U.S. Gulf coast
from the west coast of Florida to Texas and northeastern Mexico.
These swells are likely to cause life-threatening surf and rip
current conditions.  Please consult products from your local
weather office.


NEXT ADVISORY
-------------
Next intermediate advisory at 700 AM CDT.
Next complete advisory at 1000 AM CDT.

$$
Forecaster Cangialosi/Zelinsky/Blake
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